tracing: Hist trigger snapshot and onchange additions

PATCH Superseded Tom Zanussi 4 participants 21 messages Jan 15, 2019 – Jan 16, 2019

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Tom Zanussi

author

2019-01-15 22:05 UTC #0 lore raw

v12 cover tracing: Hist trigger snapshot and onchange additions

From: Tom Zanussi <[email protected]>

Hi,

This is v12 of the hist trigger snapshot and onchange additions patchset.

It addresses some comments from Namhyung regarding the 'tracing: Add alternative synthetic event trace action syntax' patch to remove parens and change the documentation to emphasize the trace() form of the synthetic event generation command.

Thanks,

Tom

v11->v12 changes:

- Removed parens from the param list specification in the trace() command description
- Changed the Documentation for synthetic event generation to emphasize the trace() form over the function-call form.

v10->v11 changes:

- Updated to use str_has_prefix() for static strings

v9->v10 changes:

- Updated to use strncmp_prefix() for static strings

v8->v9 changes:

- Moved v8 patches 17-22 to a separate series
- Moved track_data.var_ref_idx removal into 'tracing: Generalize hist trigger onmax and save action'
- Merged 'tracing: Add hist trigger handler.action documentation' into 'tracing: Refactor hist trigger action code'
- Updated patches to change all strlen() to sizeof() for string constants
- Moved test cases to the end of the series

v7->v8 changes:

- Removed /dev/null redirection from test cases
- Replaced event disable with tracing_on disable instead
- New patch to remove hist_field.var_idx and track_data.var_ref_idx
- New patch to use var_refs[] array for reference checking
- New patch to remove open-coding of var_ref count manipulation
- New patch to use var_refs[] array to destroy var_refs
- New patch to remove synth_var_refs[] now that var_refs[] is used
- New patch to add comments to variable-related fields
- Added various new comments in the patches to clarify other things
- Replaced the convoluted logic mentioned by Namhyung in update_track_val with wrappers and simpler check/save logic as suggested
- Rebased to latest ftrace/core including Masami's dynamic event framework changes

v6->v7 changes:

- Removed unnecessary HANDLER_ONMAX checks from onmax_print()/create()
- Moved handler assignment to acion_parse()
- Changed goto in ATION_TRACE case in action_create() to return
- Changed EINVAL to EEXIST in action_create() ACTION_SAVE case
- Made the return logic in create_actions() more consistent
- Merged 'tracing: Move hist trigger key printing into a separate function' into 'tracing: Add hist trigger snapshot() action'
- Updated the new snapshot, onchange, and trace test cases to match 4.20 kselftest changes.
- Added new xfail test case that make sure certain unsupported handler/action combinations fail as expected.
- While updating the test cases, realized that the other testcases in the inter-event subdir needed SPDX license updates, so added them.

v5->v6 changes:

- Added new Documentation patch explaining handler.action
- Added new README patch explaining handler.action
- Added separate snapshot() Documentation
- Added new snapshot() test case
- Updated README with snapshote()
- Added separate onchange() Documentation
- Added separate onchange() test case
- Updated README with onchange()
- Added separate trace() test case
- Updated README with trace() and <synthetic_event>() syntax

v4->v5 changes:

- added 'trace' keyword test case
- added 'onchange' handler test case

v3->v4 changes:

- added 'trace' keyword for generating synthetic events
- fix elt_data leak
- changed cond_update to cond_update_fn_t

v2->v3 changes:

- fixed problem where trace actions were only being allowed for onmatch handlers - now trace actions can be used with any handler.
- fixed problem where no action was being assigned to onmatch handlers if save or snapshot actions were specified.

v1->v2 changes:

- added missing tracing_cond_snapshot_data() definition for when CONFIG_TRACER_SNAPSHOT not defined
- removed an unnecessary WARN_ON() in track_data_snapshot_print()

Original text:

This patchset adds some useful new functions to the hist trigger code: a snapshot action and an onchange handler.

In order to make it easier to add these and in the process make the code more generic, I separated the code into explicit 'handlers' and 'actions', handlers being things like 'onmax' and 'onchange', and 'actions' being things like 'take a snapshot' or 'save some fields'.

The first few patches do that basic refactoring, which make it easier to add the subsequent changes that arbitrarily combine actions and handlers.

The fourth patch adds a 'conditional snapshot' capability that via a new tracing_snaphot_cond() function extends the existing snapshot code. It allows the caller to associate some user data with the snapshot that can be checked and saved in an update() callback whose return value determines whether the snapshot should be taken or not.

The remaining patches finally add the new snapshot action and onchange handler functionality - please see those patches for details and some examples.

Thanks,

Tom

The following changes since commit 67748dbeaf2b1240c0b87588df4bb0fb9471a751:

sh: ftrace: Fix missing parenthesis in WARN_ON() (2019-01-08 10:19:02 -0600)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/hist-snapshot-onchange-v12

Tom Zanussi (16):
tracing: Use str_has_prefix() in synth_event_create()
tracing: Refactor hist trigger action code
tracing: Make hist trigger Documentation better reflect
actions/handlers
tracing: Split up onmatch action data
tracing: Generalize hist trigger onmax and save action
tracing: Add conditional snapshot
tracing: Add hist trigger snapshot() action
tracing: Add hist trigger snapshot() action Documentation
tracing: Add hist trigger onchange() handler
tracing: Add hist trigger onchange() handler Documentation
tracing: Add alternative synthetic event trace action syntax
tracing: Add SPDX license GPL-2.0 license identifier to inter-event
testcases
tracing: Add hist trigger snapshot() action test case
tracing: Add hist trigger onchange() handler test case
tracing: Add alternative synthetic event trace action test case
tracing: Add hist trigger action 'expected fail' test case

 Documentation/trace/histogram.rst                  |  316 +++++-
 kernel/trace/trace.c                               |  176 +++-
 kernel/trace/trace.h                               |   56 +-
 kernel/trace/trace_events_hist.c                   | 1093 +++++++++++++++-----
 kernel/trace/trace_events_trigger.c                |    2 +-
 kernel/trace/trace_sched_wakeup.c                  |    2 +-
 .../inter-event/trigger-action-hist-xfail.tc       |   30 +
 .../inter-event/trigger-extended-error-support.tc  |    1 +
 .../inter-event/trigger-field-variable-support.tc  |    1 +
 .../trigger-inter-event-combined-hist.tc           |    1 +
 .../inter-event/trigger-multi-actions-accept.tc    |    1 +
 .../inter-event/trigger-onchange-action-hist.tc    |   28 +
 .../inter-event/trigger-onmatch-action-hist.tc     |    1 +
 .../trigger-onmatch-onmax-action-hist.tc           |    1 +
 .../inter-event/trigger-onmax-action-hist.tc       |    1 +
 .../inter-event/trigger-snapshot-action-hist.tc    |   43 +
 .../trigger-synthetic-event-createremove.tc        |    1 +
 .../inter-event/trigger-trace-action-hist.tc       |   42 +
 18 files changed, 1470 insertions(+), 326 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-action-hist-xfail.tc
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onchange-action-hist.tc
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-snapshot-action-hist.tc
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-trace-action-hist.tc

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #1 lore raw

PATCH v12 1/16 tracing: Use str_has_prefix() in synth_event_create()

From: Tom Zanussi <[email protected]>

Since we now have a str_has_prefix() that returns the length, we can use that instead of explicitly calculating it.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace_events_hist.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

kernel/trace/trace_events_hist.c +1 -2

index 449d90cfa151..625725ae262f 100644
@@ -1200,8 +1200,7 @@ static int synth_event_create(int argc, const char **argv)
 
 	/* This interface accepts group name prefix */
 	if (strchr(name, '/')) {
-		len = sizeof(SYNTH_SYSTEM "/") - 1;
-		if (strncmp(name, SYNTH_SYSTEM "/", len))
+		if ((len = str_has_prefix(name, SYNTH_SYSTEM "/")) == 0)
 			return -EINVAL;
 		name += len;
 	}

Signature · 1 line

2.14.1

Joe Perches

2019-01-16 04:59 UTC #2 lore raw

Re: [PATCH v12 01/16] tracing: Use str_has_prefix() in synth_event_create()

Quoted 2 lines · Tom Zanussi

Since we now have a str_has_prefix() that returns the length, we can use that instead of explicitly calculating it.

[]

kernel/trace/trace_events_hist.c

Quoted 1 line

kernel/trace/trace_events_hist.c +0 -0

[]

kernel/trace/trace_events_hist.c static int synth_event_create(int argc, const char **argv) · line 1203

Quoted 7 lines

kernel/trace/trace_events_hist.c +1 -2

@@ -1200,8 +1200,7 @@ static int synth_event_create(int argc, const char **argv)
 
 	/* This interface accepts group name prefix */
 	if (strchr(name, '/')) {
-		len = sizeof(SYNTH_SYSTEM "/") - 1;
-		if (strncmp(name, SYNTH_SYSTEM "/", len))
+		if ((len = str_has_prefix(name, SYNTH_SYSTEM "/")) == 0)

Since this is a single test, and not multiple if/else if blocks, I believe this would read better on two lines

		len = str_has_prefix(name, SYNTH_SYSTEM "/");
		if (len == 0)

Quoted 3 lines

kernel/trace/trace_events_hist.c +0 -0
 			return -EINVAL;
 		name += len;
 	}

Tom Zanussi

2019-01-16 15:50 UTC #3 lore raw

Re: [PATCH v12 01/16] tracing: Use str_has_prefix() in synth_event_create()

Hi Joe,

Quoted 23 lines · Joe Perches

Quoted 3 lines · Tom Zanussi
Since we now have a str_has_prefix() that returns the length, we can
use that instead of explicitly calculating it.
[]
kernel/trace/trace_events_hist.c
Quoted 2 lines
kernel/trace/trace_events_hist.c +0 -0
[]
kernel/trace/trace_events_hist.c static int synth_event_create(int argc, const · line 1205
Quoted 9 lines
kernel/trace/trace_events_hist.c +1 -2
@@ -1200,8 +1200,7 @@ static int synth_event_create(int argc, const
 char **argv)
 
 	/* This interface accepts group name prefix */
 	if (strchr(name, '/')) {
-		len = sizeof(SYNTH_SYSTEM "/") - 1;
-		if (strncmp(name, SYNTH_SYSTEM "/", len))
+		if ((len = str_has_prefix(name, SYNTH_SYSTEM "/")) ==
 0)
Since this is a single test, and not multiple if/else if blocks, I believe this would read better on two lines

Quoted 7 lines

		len = str_has_prefix(name, SYNTH_SYSTEM "/");
		if (len == 0)
Quoted 3 lines
kernel/trace/trace_events_hist.c +0 -0
 			return -EINVAL;
kernel/trace/trace_events_hist.c +0 -0
 		name += len;
 	}

And I was so happy to have finally found a legitimate reason to put an assignment inside an if statement, sigh. OK, I'll change it. ;-)

Thanks,

Tom

Tom Zanussi

author

2019-01-15 22:05 UTC #4 lore raw

PATCH v12 2/16 tracing: Refactor hist trigger action code

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

The hist trigger action code currently implements two essentially hard-coded pairs of 'actions' - onmax(), which tracks a variable and saves some event fields when a max is hit, and onmatch(), which is hard-coded to generate a synthetic event.

These hardcoded pairs (track max/save fields and detect match/generate synthetic event) should really be decoupled into separate components that can then be arbitrarily combined. The first component of each pair (track max/detect match) is called a 'handler' in the new code, while the second component (save fields/generate synthetic event) is called an 'action' in this scheme.

This change refactors the action code to reflect this split by adding two handlers, HANDLER_ONMATCH and HANDLER_ONMAX, along with two actions, ACTION_SAVE and ACTION_TRACE.

The new code combines them to produce the existing ONMATCH/TRACE and ONMAX/SAVE functionality, but doesn't implement the other combinations now possible. Future patches will expand these to further useful cases, such as ONMAX/TRACE, as well as add additional handlers and actions such as ONCHANGE and SNAPSHOT.

Also, add abbreviated documentation for handlers and actions to README.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace_events_hist.c | 394 +++++++++++++++++++++++----------------
 1 file changed, 231 insertions(+), 163 deletions(-)

kernel/trace/trace_events_hist.c +231 ~~-163~~

index 625725ae262f..2aeb716712d4 100644
@@ -313,9 +313,9 @@ struct hist_trigger_data {
 	struct field_var_hist		*field_var_hists[SYNTH_FIELDS_MAX];
 	unsigned int			n_field_var_hists;
 
-	struct field_var		*max_vars[SYNTH_FIELDS_MAX];
-	unsigned int			n_max_vars;
-	unsigned int			n_max_var_str;
+	struct field_var		*save_vars[SYNTH_FIELDS_MAX];
+	unsigned int			n_save_vars;
+	unsigned int			n_save_var_str;
 };
 
 static int synth_event_create(int argc, const char **argv);

@@ -386,8 +386,22 @@ typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
 			     struct ring_buffer_event *rbe,
 			     struct action_data *data, u64 *var_ref_vals);
 
+enum handler_id {
+	HANDLER_ONMATCH = 1,
+	HANDLER_ONMAX,
+};
+
+enum action_id {
+	ACTION_SAVE = 1,
+	ACTION_TRACE,
+};
+
 struct action_data {
+	enum handler_id		handler;
+	enum action_id		action;
+	char			*action_name;
 	action_fn_t		fn;
+
 	unsigned int		n_params;
 	char			*params[SYNTH_FIELDS_MAX];

@@ -404,13 +418,11 @@ struct action_data {
 			unsigned int		var_ref_idx;
 			char			*match_event;
 			char			*match_event_system;
-			char			*synth_event_name;
 			struct synth_event	*synth_event;
 		} onmatch;
 
 		struct {
 			char			*var_str;
-			char			*fn_name;
 			unsigned int		max_var_ref_idx;
 			struct hist_field	*max_var;
 			struct hist_field	*var;

@@ -1643,7 +1655,7 @@ find_match_var(struct hist_trigger_data *hist_data, char *var_name)
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
 
-		if (data->fn == action_trace) {
+		if (data->handler == HANDLER_ONMATCH) {
 			char *system = data->onmatch.match_event_system;
 			char *event_name = data->onmatch.match_event;

@@ -2075,7 +2087,7 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
 		}
 	}
 
-	n_str = hist_data->n_field_var_str + hist_data->n_max_var_str;
+	n_str = hist_data->n_field_var_str + hist_data->n_save_var_str;
 
 	size = STR_VAR_LEN_MAX;

@@ -3049,7 +3061,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 	int ret;
 
 	if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) {
-		hist_err_event("onmatch: Too many field variables defined: ",
+		hist_err_event("trace action: Too many field variables defined: ",
 			       subsys_name, event_name, field_name);
 		return ERR_PTR(-EINVAL);
 	}

@@ -3057,7 +3069,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 	file = event_file(tr, subsys_name, event_name);
 
 	if (IS_ERR(file)) {
-		hist_err_event("onmatch: Event file not found: ",
+		hist_err_event("trace action: Event file not found: ",
 			       subsys_name, event_name, field_name);
 		ret = PTR_ERR(file);
 		return ERR_PTR(ret);

@@ -3071,7 +3083,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 	 */
 	hist_data = find_compatible_hist(target_hist_data, file);
 	if (!hist_data) {
-		hist_err_event("onmatch: Matching event histogram not found: ",
+		hist_err_event("trace action: Matching event histogram not found: ",
 			       subsys_name, event_name, field_name);
 		return ERR_PTR(-EINVAL);
 	}

@@ -3133,7 +3145,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 		kfree(cmd);
 		kfree(var_hist->cmd);
 		kfree(var_hist);
-		hist_err_event("onmatch: Couldn't create histogram for field: ",
+		hist_err_event("trace action: Couldn't create histogram for field: ",
 			       subsys_name, event_name, field_name);
 		return ERR_PTR(ret);
 	}

@@ -3146,7 +3158,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 	if (IS_ERR_OR_NULL(event_var)) {
 		kfree(var_hist->cmd);
 		kfree(var_hist);
-		hist_err_event("onmatch: Couldn't find synthetic variable: ",
+		hist_err_event("trace action: Couldn't find synthetic variable: ",
 			       subsys_name, event_name, field_name);
 		return ERR_PTR(-EINVAL);
 	}

@@ -3229,8 +3241,8 @@ static void update_max_vars(struct hist_trigger_data *hist_data,
 			    struct ring_buffer_event *rbe,
 			    void *rec)
 {
-	__update_field_vars(elt, rbe, rec, hist_data->max_vars,
-			    hist_data->n_max_vars, hist_data->n_field_var_str);
+	__update_field_vars(elt, rbe, rec, hist_data->save_vars,
+			    hist_data->n_save_vars, hist_data->n_field_var_str);
 }
 
 static struct hist_field *create_var(struct hist_trigger_data *hist_data,

@@ -3374,9 +3386,9 @@ static void onmax_print(struct seq_file *m,
 
 	seq_printf(m, "\n\tmax: %10llu", tracing_map_read_var(elt, max_idx));
 
-	for (i = 0; i < hist_data->n_max_vars; i++) {
-		struct hist_field *save_val = hist_data->max_vars[i]->val;
-		struct hist_field *save_var = hist_data->max_vars[i]->var;
+	for (i = 0; i < hist_data->n_save_vars; i++) {
+		struct hist_field *save_val = hist_data->save_vars[i]->val;
+		struct hist_field *save_var = hist_data->save_vars[i]->var;
 		u64 val;
 
 		save_var_idx = save_var->var.idx;

@@ -3420,7 +3432,7 @@ static void onmax_destroy(struct action_data *data)
 	destroy_hist_field(data->onmax.var, 0);
 
 	kfree(data->onmax.var_str);
-	kfree(data->onmax.fn_name);
+	kfree(data->action_name);
 
 	for (i = 0; i < data->n_params; i++)
 		kfree(data->params[i]);

@@ -3428,15 +3440,16 @@ static void onmax_destroy(struct action_data *data)
 	kfree(data);
 }
 
+static int action_create(struct hist_trigger_data *hist_data,
+			 struct action_data *data);
+
 static int onmax_create(struct hist_trigger_data *hist_data,
 			struct action_data *data)
 {
+	struct hist_field *var_field, *ref_field, *max_var = NULL;
 	struct trace_event_file *file = hist_data->event_file;
-	struct hist_field *var_field, *ref_field, *max_var;
 	unsigned int var_ref_idx = hist_data->n_var_refs;
-	struct field_var *field_var;
-	char *onmax_var_str, *param;
-	unsigned int i;
+	char *onmax_var_str;
 	int ret = 0;
 
 	onmax_var_str = data->onmax.var_str;

@@ -3458,8 +3471,8 @@ static int onmax_create(struct hist_trigger_data *hist_data,
 
 	data->onmax.var = ref_field;
 
-	data->fn = onmax_save;
 	data->onmax.max_var_ref_idx = var_ref_idx;
+
 	max_var = create_var(hist_data, file, "max", sizeof(u64), "u64");
 	if (IS_ERR(max_var)) {
 		hist_err("onmax: Couldn't create onmax variable: ", "max");

@@ -3468,27 +3481,7 @@ static int onmax_create(struct hist_trigger_data *hist_data,
 	}
 	data->onmax.max_var = max_var;
 
-	for (i = 0; i < data->n_params; i++) {
-		param = kstrdup(data->params[i], GFP_KERNEL);
-		if (!param) {
-			ret = -ENOMEM;
-			goto out;
-		}
-
-		field_var = create_target_field_var(hist_data, NULL, NULL, param);
-		if (IS_ERR(field_var)) {
-			hist_err("onmax: Couldn't create field variable: ", param);
-			ret = PTR_ERR(field_var);
-			kfree(param);
-			goto out;
-		}
-
-		hist_data->max_vars[hist_data->n_max_vars++] = field_var;
-		if (field_var->val->flags & HIST_FIELD_FL_STRING)
-			hist_data->n_max_var_str++;
-
-		kfree(param);
-	}
+	ret = action_create(hist_data, data);
  out:
 	return ret;
 }

@@ -3499,11 +3492,14 @@ static int parse_action_params(char *params, struct action_data *data)
 	int ret = 0;
 
 	while (params) {
-		if (data->n_params >= SYNTH_FIELDS_MAX)
+		if (data->n_params >= SYNTH_FIELDS_MAX) {
+			hist_err("Too many action params", "");
 			goto out;
+		}
 
 		param = strsep(&params, ",");
 		if (!param) {
+			hist_err("No action param found", "");
 			ret = -EINVAL;
 			goto out;
 		}

@@ -3527,10 +3523,71 @@ static int parse_action_params(char *params, struct action_data *data)
 	return ret;
 }
 
-static struct action_data *onmax_parse(char *str)
+static int action_parse(char *str, struct action_data *data,
+			enum handler_id handler)
+{
+	char *action_name;
+	int ret = 0;
+
+	strsep(&str, ".");
+	if (!str) {
+		hist_err("action parsing: No action found", "");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	action_name = strsep(&str, "(");
+	if (!action_name || !str) {
+		hist_err("action parsing: No action found", "");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (str_has_prefix(action_name, "save")) {
+		char *params = strsep(&str, ")");
+
+		if (!params) {
+			hist_err("action parsing: No params found for %s", "save");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = parse_action_params(params, data);
+		if (ret)
+			goto out;
+
+		if (handler == HANDLER_ONMAX)
+			data->fn = onmax_save;
+
+		data->action = ACTION_SAVE;
+	} else {
+		char *params = strsep(&str, ")");
+
+		if (params) {
+			ret = parse_action_params(params, data);
+			if (ret)
+				goto out;
+		}
+
+		data->fn = action_trace;
+		data->action = ACTION_TRACE;
+	}
+
+	data->action_name = kstrdup(action_name, GFP_KERNEL);
+	if (!data->action_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	data->handler = handler;
+ out:
+	return ret;
+}
+
+static struct action_data *onmax_parse(char *str, enum handler_id handler)
 {
-	char *onmax_fn_name, *onmax_var_str;
 	struct action_data *data;
+	char *onmax_var_str;
 	int ret = -EINVAL;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);

@@ -3549,33 +3606,9 @@ static struct action_data *onmax_parse(char *str)
 		goto free;
 	}
 
-	strsep(&str, ".");
-	if (!str)
-		goto free;
-
-	onmax_fn_name = strsep(&str, "(");
-	if (!onmax_fn_name || !str)
-		goto free;
-
-	if (str_has_prefix(onmax_fn_name, "save")) {
-		char *params = strsep(&str, ")");
-
-		if (!params) {
-			ret = -EINVAL;
-			goto free;
-		}
-
-		ret = parse_action_params(params, data);
-		if (ret)
-			goto free;
-	} else
-		goto free;
-
-	data->onmax.fn_name = kstrdup(onmax_fn_name, GFP_KERNEL);
-	if (!data->onmax.fn_name) {
-		ret = -ENOMEM;
+	ret = action_parse(str, data, handler);
+	if (ret)
 		goto free;
-	}
  out:
 	return data;
  free:

@@ -3592,7 +3625,7 @@ static void onmatch_destroy(struct action_data *data)
 
 	kfree(data->onmatch.match_event);
 	kfree(data->onmatch.match_event_system);
-	kfree(data->onmatch.synth_event_name);
+	kfree(data->action_name);
 
 	for (i = 0; i < data->n_params; i++)
 		kfree(data->params[i]);

@@ -3650,8 +3683,9 @@ static int check_synth_field(struct synth_event *event,
 }
 
 static struct hist_field *
-onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
-		 char *system, char *event, char *var)
+trace_action_find_var(struct hist_trigger_data *hist_data,
+		      struct action_data *data,
+		      char *system, char *event, char *var)
 {
 	struct hist_field *hist_field;

@@ -3659,7 +3693,7 @@ onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
 
 	hist_field = find_target_event_var(hist_data, system, event, var);
 	if (!hist_field) {
-		if (!system) {
+		if (!system && data->handler == HANDLER_ONMATCH) {
 			system = data->onmatch.match_event_system;
 			event = data->onmatch.match_event;
 		}

@@ -3668,15 +3702,15 @@ onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
 	}
 
 	if (!hist_field)
-		hist_err_event("onmatch: Couldn't find onmatch param: $", system, event, var);
+		hist_err_event("trace action: Couldn't find param: $", system, event, var);
 
 	return hist_field;
 }
 
 static struct hist_field *
-onmatch_create_field_var(struct hist_trigger_data *hist_data,
-			 struct action_data *data, char *system,
-			 char *event, char *var)
+trace_action_create_field_var(struct hist_trigger_data *hist_data,
+			      struct action_data *data, char *system,
+			      char *event, char *var)
 {
 	struct hist_field *hist_field = NULL;
 	struct field_var *field_var;

@@ -3699,7 +3733,7 @@ onmatch_create_field_var(struct hist_trigger_data *hist_data,
 		 * looking for fields on the onmatch(system.event.xxx)
 		 * event.
 		 */
-		if (!system) {
+		if (!system && data->handler == HANDLER_ONMATCH) {
 			system = data->onmatch.match_event_system;
 			event = data->onmatch.match_event;
 		}

@@ -3723,9 +3757,8 @@ onmatch_create_field_var(struct hist_trigger_data *hist_data,
 	goto out;
 }
 
-static int onmatch_create(struct hist_trigger_data *hist_data,
-			  struct trace_event_file *file,
-			  struct action_data *data)
+static int trace_action_create(struct hist_trigger_data *hist_data,
+			       struct action_data *data)
 {
 	char *event_name, *param, *system = NULL;
 	struct hist_field *hist_field, *var_ref;

@@ -3736,11 +3769,12 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 
 	lockdep_assert_held(&event_mutex);
 
-	event = find_synth_event(data->onmatch.synth_event_name);
+	event = find_synth_event(data->action_name);
 	if (!event) {
-		hist_err("onmatch: Couldn't find synthetic event: ", data->onmatch.synth_event_name);
+		hist_err("trace action: Couldn't find synthetic event: ", data->action_name);
 		return -EINVAL;
 	}
+
 	event->ref++;
 
 	var_ref_idx = hist_data->n_var_refs;

@@ -3768,13 +3802,15 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 		}
 
 		if (param[0] == '$')
-			hist_field = onmatch_find_var(hist_data, data, system,
-						      event_name, param);
+			hist_field = trace_action_find_var(hist_data, data,
+							   system, event_name,
+							   param);
 		else
-			hist_field = onmatch_create_field_var(hist_data, data,
-							      system,
-							      event_name,
-							      param);
+			hist_field = trace_action_create_field_var(hist_data,
+								   data,
+								   system,
+								   event_name,
+								   param);
 
 		if (!hist_field) {
 			kfree(p);

@@ -3796,7 +3832,7 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 			continue;
 		}
 
-		hist_err_event("onmatch: Param type doesn't match synthetic event field type: ",
+		hist_err_event("trace action: Param type doesn't match synthetic event field type: ",
 			       system, event_name, param);
 		kfree(p);
 		ret = -EINVAL;

@@ -3804,12 +3840,11 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 	}
 
 	if (field_pos != event->n_fields) {
-		hist_err("onmatch: Param count doesn't match synthetic event field count: ", event->name);
+		hist_err("trace action: Param count doesn't match synthetic event field count: ", event->name);
 		ret = -EINVAL;
 		goto err;
 	}
 
-	data->fn = action_trace;
 	data->onmatch.synth_event = event;
 	data->onmatch.var_ref_idx = var_ref_idx;
  out:

@@ -3820,10 +3855,58 @@ static int onmatch_create(struct hist_trigger_data *hist_data,
 	goto out;
 }
 
+static int action_create(struct hist_trigger_data *hist_data,
+			 struct action_data *data)
+{
+	struct field_var *field_var;
+	unsigned int i;
+	char *param;
+	int ret = 0;
+
+	if (data->action == ACTION_TRACE)
+		return trace_action_create(hist_data, data);
+
+	if (data->action == ACTION_SAVE) {
+		if (hist_data->n_save_vars) {
+			ret = -EEXIST;
+			hist_err("save action: Can't have more than one save() action per hist", "");
+			goto out;
+		}
+
+		for (i = 0; i < data->n_params; i++) {
+			param = kstrdup(data->params[i], GFP_KERNEL);
+			if (!param) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			field_var = create_target_field_var(hist_data, NULL, NULL, param);
+			if (IS_ERR(field_var)) {
+				hist_err("save action: Couldn't create field variable: ", param);
+				ret = PTR_ERR(field_var);
+				kfree(param);
+				goto out;
+			}
+
+			hist_data->save_vars[hist_data->n_save_vars++] = field_var;
+			if (field_var->val->flags & HIST_FIELD_FL_STRING)
+				hist_data->n_save_var_str++;
+			kfree(param);
+		}
+	}
+ out:
+	return ret;
+}
+
+static int onmatch_create(struct hist_trigger_data *hist_data,
+			  struct action_data *data)
+{
+	return action_create(hist_data, data);
+}
+
 static struct action_data *onmatch_parse(struct trace_array *tr, char *str)
 {
 	char *match_event, *match_event_system;
-	char *synth_event_name, *params;
 	struct action_data *data;
 	int ret = -EINVAL;

@@ -3861,31 +3944,7 @@ static struct action_data *onmatch_parse(struct trace_array *tr, char *str)
 		goto free;
 	}
 
-	strsep(&str, ".");
-	if (!str) {
-		hist_err("onmatch: Missing . after onmatch(): ", str);
-		goto free;
-	}
-
-	synth_event_name = strsep(&str, "(");
-	if (!synth_event_name || !str) {
-		hist_err("onmatch: Missing opening paramlist paren: ", synth_event_name);
-		goto free;
-	}
-
-	data->onmatch.synth_event_name = kstrdup(synth_event_name, GFP_KERNEL);
-	if (!data->onmatch.synth_event_name) {
-		ret = -ENOMEM;
-		goto free;
-	}
-
-	params = strsep(&str, ")");
-	if (!params || !str || (str && strlen(str))) {
-		hist_err("onmatch: Missing closing paramlist paren: ", params);
-		goto free;
-	}
-
-	ret = parse_action_params(params, data);
+	ret = action_parse(str, data, HANDLER_ONMATCH);
 	if (ret)
 		goto free;
  out:

@@ -4325,9 +4384,9 @@ static void destroy_actions(struct hist_trigger_data *hist_data)
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
 
-		if (data->fn == action_trace)
+		if (data->handler == HANDLER_ONMATCH)
 			onmatch_destroy(data);
-		else if (data->fn == onmax_save)
+		else if (data->handler == HANDLER_ONMAX)
 			onmax_destroy(data);
 		else
 			kfree(data);

@@ -4354,16 +4413,14 @@ static int parse_actions(struct hist_trigger_data *hist_data)
 				ret = PTR_ERR(data);
 				break;
 			}
-			data->fn = action_trace;
 		} else if ((len = str_has_prefix(str, "onmax("))) {
 			char *action_str = str + len;
 
-			data = onmax_parse(action_str);
+			data = onmax_parse(action_str, HANDLER_ONMAX);
 			if (IS_ERR(data)) {
 				ret = PTR_ERR(data);
 				break;
 			}
-			data->fn = onmax_save;
 		} else {
 			ret = -EINVAL;
 			break;

@@ -4375,8 +4432,7 @@ static int parse_actions(struct hist_trigger_data *hist_data)
 	return ret;
 }
 
-static int create_actions(struct hist_trigger_data *hist_data,
-			  struct trace_event_file *file)
+static int create_actions(struct hist_trigger_data *hist_data)
 {
 	struct action_data *data;
 	unsigned int i;

@@ -4385,14 +4441,17 @@ static int create_actions(struct hist_trigger_data *hist_data,
 	for (i = 0; i < hist_data->attrs->n_actions; i++) {
 		data = hist_data->actions[i];
 
-		if (data->fn == action_trace) {
-			ret = onmatch_create(hist_data, file, data);
+		if (data->handler == HANDLER_ONMATCH) {
+			ret = onmatch_create(hist_data, data);
 			if (ret)
-				return ret;
-		} else if (data->fn == onmax_save) {
+				break;
+		} else if (data->handler == HANDLER_ONMAX) {
 			ret = onmax_create(hist_data, data);
 			if (ret)
-				return ret;
+				break;
+		} else {
+			ret = -EINVAL;
+			break;
 		}
 	}

@@ -4408,26 +4467,42 @@ static void print_actions(struct seq_file *m,
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
 
-		if (data->fn == onmax_save)
+		if (data->handler == HANDLER_ONMAX)
 			onmax_print(m, hist_data, elt, data);
 	}
 }
 
+static void print_action_spec(struct seq_file *m,
+			      struct hist_trigger_data *hist_data,
+			      struct action_data *data)
+{
+	unsigned int i;
+
+	if (data->action == ACTION_SAVE) {
+		for (i = 0; i < hist_data->n_save_vars; i++) {
+			seq_printf(m, "%s", hist_data->save_vars[i]->var->var.name);
+			if (i < hist_data->n_save_vars - 1)
+				seq_puts(m, ",");
+		}
+	} else if (data->action == ACTION_TRACE) {
+		for (i = 0; i < data->n_params; i++) {
+			if (i)
+				seq_puts(m, ",");
+			seq_printf(m, "%s", data->params[i]);
+		}
+	}
+}
+
 static void print_onmax_spec(struct seq_file *m,
 			     struct hist_trigger_data *hist_data,
 			     struct action_data *data)
 {
-	unsigned int i;
-
 	seq_puts(m, ":onmax(");
 	seq_printf(m, "%s", data->onmax.var_str);
-	seq_printf(m, ").%s(", data->onmax.fn_name);
+	seq_printf(m, ").%s(", data->action_name);
+
+	print_action_spec(m, hist_data, data);
 
-	for (i = 0; i < hist_data->n_max_vars; i++) {
-		seq_printf(m, "%s", hist_data->max_vars[i]->var->var.name);
-		if (i < hist_data->n_max_vars - 1)
-			seq_puts(m, ",");
-	}
 	seq_puts(m, ")");
 }

@@ -4435,18 +4510,12 @@ static void print_onmatch_spec(struct seq_file *m,
 			       struct hist_trigger_data *hist_data,
 			       struct action_data *data)
 {
-	unsigned int i;
-
 	seq_printf(m, ":onmatch(%s.%s).", data->onmatch.match_event_system,
 		   data->onmatch.match_event);
 
-	seq_printf(m, "%s(", data->onmatch.synth_event->name);
+	seq_printf(m, "%s(", data->action_name);
 
-	for (i = 0; i < data->n_params; i++) {
-		if (i)
-			seq_puts(m, ",");
-		seq_printf(m, "%s", data->params[i]);
-	}
+	print_action_spec(m, hist_data, data);
 
 	seq_puts(m, ")");
 }

@@ -4463,7 +4532,9 @@ static bool actions_match(struct hist_trigger_data *hist_data,
 		struct action_data *data = hist_data->actions[i];
 		struct action_data *data_test = hist_data_test->actions[i];
 
-		if (data->fn != data_test->fn)
+		if (data->handler != data_test->handler)
+			return false;
+		if (data->action != data_test->action)
 			return false;
 
 		if (data->n_params != data_test->n_params)

@@ -4474,23 +4545,20 @@ static bool actions_match(struct hist_trigger_data *hist_data,
 				return false;
 		}
 
-		if (data->fn == action_trace) {
-			if (strcmp(data->onmatch.synth_event_name,
-				   data_test->onmatch.synth_event_name) != 0)
-				return false;
+		if (strcmp(data->action_name, data_test->action_name) != 0)
+			return false;
+
+		if (data->handler == HANDLER_ONMATCH) {
 			if (strcmp(data->onmatch.match_event_system,
 				   data_test->onmatch.match_event_system) != 0)
 				return false;
 			if (strcmp(data->onmatch.match_event,
 				   data_test->onmatch.match_event) != 0)
 				return false;
-		} else if (data->fn == onmax_save) {
+		} else if (data->handler == HANDLER_ONMAX) {
 			if (strcmp(data->onmax.var_str,
 				   data_test->onmax.var_str) != 0)
 				return false;
-			if (strcmp(data->onmax.fn_name,
-				   data_test->onmax.fn_name) != 0)
-				return false;
 		}
 	}

@@ -4506,9 +4574,9 @@ static void print_actions_spec(struct seq_file *m,
 	for (i = 0; i < hist_data->n_actions; i++) {
 		struct action_data *data = hist_data->actions[i];
 
-		if (data->fn == action_trace)
+		if (data->handler == HANDLER_ONMATCH)
 			print_onmatch_spec(m, hist_data, data);
-		else if (data->fn == onmax_save)
+		else if (data->handler == HANDLER_ONMAX)
 			print_onmax_spec(m, hist_data, data);
 	}
 }

@@ -5682,7 +5750,7 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 	if (has_hist_vars(hist_data))
 		save_hist_vars(hist_data);
 
-	ret = create_actions(hist_data, file);
+	ret = create_actions(hist_data);
 	if (ret)
 		goto out_unreg;

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #5 lore raw

PATCH v12 3/16 tracing: Make hist trigger Documentation better reflect actions/handlers

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

The action/handler code refactoring didn't change the action/handler syntax, but did generalize it - the Documentation should reflect that.

Signed-off-by Tom Zanussi <[email protected]>

---
 Documentation/trace/histogram.rst | 56 ++++++++++++++++++++++++++++++---------
 1 file changed, 43 insertions(+), 13 deletions(-)

Documentation/trace/histogram.rst +43 ~~-13~~

index 7dda76503127..63e522107e59 100644
@@ -25,7 +25,7 @@ Documentation written by Tom Zanussi
 
         hist:keys=<field1[,field2,...]>[:values=<field1[,field2,...]>]
           [:sort=<field1[,field2,...]>][:size=#entries][:pause][:continue]
-          [:clear][:name=histname1] [if <filter>]
+          [:clear][:name=histname1][:<handler>.<action>] [if <filter>]
 
   When a matching event is hit, an entry is added to a hash table
   using the key(s) and value(s) named.  Keys and values correspond to

@@ -1831,21 +1831,51 @@ and looks and behaves just like any other event::
 Like any other event, once a histogram is enabled for the event, the
 output can be displayed by reading the event's 'hist' file.
 
-2.2.3 Hist trigger 'actions'
-----------------------------
+2.2.3 Hist trigger 'handlers' and 'actions'
+-------------------------------------------
 
-A hist trigger 'action' is a function that's executed whenever a
-histogram entry is added or updated.
+A hist trigger 'action' is a function that's executed (in most cases
+conditionally) whenever a histogram entry is added or updated.
 
-The default 'action' if no special function is explicitly specified is
-as it always has been, to simply update the set of values associated
-with an entry.  Some applications, however, may want to perform
-additional actions at that point, such as generate another event, or
-compare and save a maximum.
+When a histogram entry is added or updated, a hist trigger 'handler'
+is what decides whether the corresponding action is actually invoked
+or not.
 
-The following additional actions are available.  To specify an action
-for a given event, simply specify the action between colons in the
-hist trigger specification.
+Hist trigger handlers and actions are paired together in the general
+form:
+
+  <handler>.<action>
+
+To specify a handler.action pair for a given event, simply specify
+that handler.action pair between colons in the hist trigger
+specification.
+
+In theory, any handler can be combined with any action, but in
+practice, not every handler.action combination is currently supported;
+if a given handler.action combination isn't supported, the hist
+trigger will fail with -EINVAL;
+
+The default 'handler.action' if none is explicity specified is as it
+always has been, to simply update the set of values associated with an
+entry.  Some applications, however, may want to perform additional
+actions at that point, such as generate another event, or compare and
+save a maximum.
+
+The supported handlers and actions are listed below, and each is
+described in more detail in the following paragraphs, in the context
+of descriptions of some common and useful handler.action combinations.
+
+The available handlers are:
+
+  - onmatch(matching.event)    - invoke action on any addition or update
+  - onmax(var)                 - invoke action if var exceeds current max
+
+The available actions are:
+
+  - <synthetic_event_name>(param list)         - generate synthetic event
+  - save(field,...)                            - save current event fields
+
+The following commonly-used handler.action pairs are available:
 
   - onmatch(matching.event).<synthetic_event_name>(param list)

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #6 lore raw

PATCH v12 4/16 tracing: Split up onmatch action data

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Currently, the onmatch action data binds the onmatch action to data related to synthetic event generation. Since we want to allow the onmatch handler to potentially invoke a different action, and because we expect other handlers to generate synthetic events, we need to separate the data related to these two functions.

Also rename the onmatch data to something more descriptive, and create and use common action data destroy function.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace.c             |  12 ++++-
 kernel/trace/trace_events_hist.c | 103 ++++++++++++++++++++-------------------
 2 files changed, 63 insertions(+), 52 deletions(-)

kernel/trace/trace.c +11 -1

index 18b86c3974e1..188c4e06c1cc 100644
@@ -4700,6 +4700,7 @@ static const char readme_msg[] =
 	"\t            [:size=#entries]\n"
 	"\t            [:pause][:continue][:clear]\n"
 	"\t            [:name=histname1]\n"
+	"\t            [:<handler>.<action>]\n"
 	"\t            [if <filter>]\n\n"
 	"\t    When a matching event is hit, an entry is added to a hash\n"
 	"\t    table using the key(s) and value(s) named, and the value of a\n"

@@ -4741,7 +4742,16 @@ static const char readme_msg[] =
 	"\t    The enable_hist and disable_hist triggers can be used to\n"
 	"\t    have one event conditionally start and stop another event's\n"
 	"\t    already-attached hist trigger.  The syntax is analagous to\n"
-	"\t    the enable_event and disable_event triggers.\n"
+	"\t    the enable_event and disable_event triggers.\n\n"
+	"\t    Hist trigger handlers and actions are executed whenever a\n"
+	"\t    a histogram entry is added or updated.  They take the form:\n\n"
+	"\t        <handler>.<action>\n\n"
+	"\t    The available handlers are:\n\n"
+	"\t        onmatch(matching.event)  - invoke on addition or update\n"
+	"\t        onmax(var)               - invoke if var exceeds current max\n\n"
+	"\t    The available actions are:\n\n"
+	"\t        <synthetic_event>(param list)        - generate synthetic event\n"
+	"\t        save(field,...)                      - save current event fields\n"
 #endif
 ;

kernel/trace/trace_events_hist.c +52 ~~-51~~

190 lines not on this page · raw message

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #7 lore raw

PATCH v12 5/16 tracing: Generalize hist trigger onmax and save action

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

The action refactor code allowed actions and handlers to be separated, but the existing onmax handler and save action code is still not flexible enough to handle arbitrary coupling. This change generalizes them and in the process makes additional handlers and actions easier to implement.

The onmax action can be broken up and thought of as two separate components - a variable to be tracked (the parameter given to the onmax($var_to_track) function) and an invisible variable created to save the ongoing result of doing something with that variable, such as saving the max value of that variable so far seen.

Separating it out like this and renaming it appropriately allows us to use the same code for similar tracking functions such as onchange($var_to_track), which would just track the last value seen rather than the max seen so far, which is useful in some situations.

Additionally, because different handlers and actions may want to save and access data differently e.g. save and retrieve tracking values as local variables vs something more global, save_val() and get_val() interface functions are introduced and max-specific implementations are used instead.

The same goes for the code that checks whether a maximum has been hit
- a generic check_val() interface and max-checking implementation is used instead, which allows future patches to make use of he same code using their own implemetations of similar functionality.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace_events_hist.c | 257 +++++++++++++++++++++++++++------------
 1 file changed, 181 insertions(+), 76 deletions(-)

kernel/trace/trace_events_hist.c +181 ~~-76~~

index f0e9667a29c6..d5c0b3f67804 100644
@@ -386,6 +386,15 @@ typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
 			     struct ring_buffer_event *rbe,
 			     struct action_data *data, u64 *var_ref_vals);
 
+typedef bool (*check_track_val_fn_t) (u64 track_val, u64 var_val);
+typedef void (*save_track_val_fn_t) (struct hist_trigger_data *hist_data,
+				     struct tracing_map_elt *elt,
+				     struct action_data *data,
+				     unsigned int track_var_idx, u64 var_val);
+typedef u64 (*get_track_val_fn_t) (struct hist_trigger_data *hist_data,
+				   struct tracing_map_elt *elt,
+				   struct action_data *data);
+
 enum handler_id {
 	HANDLER_ONMATCH = 1,
 	HANDLER_ONMAX,

@@ -423,15 +432,37 @@ struct action_data {
 		} match_data;
 
 		struct {
+			/*
+			 * var_str contains the $-unstripped variable
+			 * name referenced by var_ref, and used when
+			 * printing the action.  Because var_ref
+			 * creation is deferred to create_actions(),
+			 * we need a per-action way to save it until
+			 * then, thus var_str.
+			 */
 			char			*var_str;
-			unsigned int		max_var_ref_idx;
-			struct hist_field	*max_var;
-			struct hist_field	*var;
-		} onmax;
+
+			/*
+			 * var_ref refers to the variable being
+			 * tracked e.g onmax($var).
+			 */
+			struct hist_field	*var_ref;
+
+			/*
+			 * track_var contains the 'invisible' tracking
+			 * variable created to keep the current
+			 * e.g. max value.
+			 */
+			struct hist_field	*track_var;
+
+			check_track_val_fn_t	check_val;
+			save_track_val_fn_t	save_val;
+			action_fn_t		save_data;
+			get_track_val_fn_t	get_val;
+		} track_data;
 	};
 };
 
-
 static char last_hist_cmd[MAX_FILTER_STR_VAL];
 static char hist_err_str[MAX_FILTER_STR_VAL];

@@ -3237,10 +3268,10 @@ static void update_field_vars(struct hist_trigger_data *hist_data,
 			    hist_data->n_field_vars, 0);
 }
 
-static void update_max_vars(struct hist_trigger_data *hist_data,
-			    struct tracing_map_elt *elt,
-			    struct ring_buffer_event *rbe,
-			    void *rec)
+static void save_track_data_vars(struct hist_trigger_data *hist_data,
+				 struct tracing_map_elt *elt, void *rec,
+				 struct ring_buffer_event *rbe,
+				 struct action_data *data, u64 *var_ref_vals)
 {
 	__update_field_vars(elt, rbe, rec, hist_data->save_vars,
 			    hist_data->n_save_vars, hist_data->n_field_var_str);

@@ -3378,14 +3409,73 @@ create_target_field_var(struct hist_trigger_data *target_hist_data,
 	return create_field_var(target_hist_data, file, var_name);
 }
 
-static void onmax_print(struct seq_file *m,
-			struct hist_trigger_data *hist_data,
-			struct tracing_map_elt *elt,
-			struct action_data *data)
+static bool check_track_val_max(u64 track_val, u64 var_val)
+{
+	if (var_val <= track_val)
+		return false;
+
+	return true;
+}
+
+static u64 get_track_val_local(struct hist_trigger_data *hist_data,
+			       struct tracing_map_elt *elt,
+			       struct action_data *data)
+{
+	unsigned int track_var_idx = data->track_data.track_var->var.idx;
+	u64 track_val;
+
+	track_val = tracing_map_read_var(elt, track_var_idx);
+
+	return track_val;
+}
+
+static void save_track_val_local(struct hist_trigger_data *hist_data,
+				 struct tracing_map_elt *elt,
+				 struct action_data *data,
+				 unsigned int track_var_idx, u64 var_val)
+{
+	tracing_map_set_var(elt, track_var_idx, var_val);
+}
+
+static void save_track_val(struct hist_trigger_data *hist_data,
+			   struct tracing_map_elt *elt,
+			   struct action_data *data,
+			   u64 var_val)
+{
+	unsigned int track_var_idx = data->track_data.track_var->var.idx;
+
+	data->track_data.save_val(hist_data, elt, data, track_var_idx, var_val);
+}
+
+static void save_track_data(struct hist_trigger_data *hist_data,
+			    struct tracing_map_elt *elt, void *rec,
+			    struct ring_buffer_event *rbe,
+			    struct action_data *data, u64 *var_ref_vals)
+{
+	if (data->track_data.save_data)
+		data->track_data.save_data(hist_data, elt, rec, rbe, data, var_ref_vals);
+}
+
+static bool check_track_val(struct tracing_map_elt *elt,
+			    struct action_data *data,
+			    u64 var_val)
 {
-	unsigned int i, save_var_idx, max_idx = data->onmax.max_var->var.idx;
+	unsigned int track_var_idx = data->track_data.track_var->var.idx;
+	u64 track_val = tracing_map_read_var(elt, track_var_idx);
 
-	seq_printf(m, "\n\tmax: %10llu", tracing_map_read_var(elt, max_idx));
+	return data->track_data.check_val(track_val, var_val);
+}
+
+static void track_data_print(struct seq_file *m,
+			     struct hist_trigger_data *hist_data,
+			     struct tracing_map_elt *elt,
+			     struct action_data *data)
+{
+	u64 track_val = data->track_data.get_val(hist_data, elt, data);
+	unsigned int i, save_var_idx;
+
+	if (data->handler == HANDLER_ONMAX)
+		seq_printf(m, "\n\tmax: %10llu", track_val);
 
 	for (i = 0; i < hist_data->n_save_vars; i++) {
 		struct hist_field *save_val = hist_data->save_vars[i]->val;

@@ -3404,25 +3494,17 @@ static void onmax_print(struct seq_file *m,
 	}
 }
 
-static void onmax_save(struct hist_trigger_data *hist_data,
-		       struct tracing_map_elt *elt, void *rec,
-		       struct ring_buffer_event *rbe,
-		       struct action_data *data, u64 *var_ref_vals)
+static void ontrack_action(struct hist_trigger_data *hist_data,
+			   struct tracing_map_elt *elt, void *rec,
+			   struct ring_buffer_event *rbe,
+			   struct action_data *data, u64 *var_ref_vals)
 {
-	unsigned int max_idx = data->onmax.max_var->var.idx;
-	unsigned int max_var_ref_idx = data->onmax.max_var_ref_idx;
+	u64 var_val = var_ref_vals[data->track_data.var_ref->var_ref_idx];
 
-	u64 var_val, max_val;
-
-	var_val = var_ref_vals[max_var_ref_idx];
-	max_val = tracing_map_read_var(elt, max_idx);
-
-	if (var_val <= max_val)
-		return;
-
-	tracing_map_set_var(elt, max_idx, var_val);
-
-	update_max_vars(hist_data, elt, rbe, rec);
+	if (check_track_val(elt, data, var_val)) {
+		save_track_val(hist_data, elt, data, var_val);
+		save_track_data(hist_data, elt, rec, rbe, data, var_ref_vals);
+	}
 }
 
 static void action_data_destroy(struct action_data *data)

@@ -3442,12 +3524,13 @@ static void action_data_destroy(struct action_data *data)
 	kfree(data);
 }
 
-static void onmax_destroy(struct action_data *data)
+static void track_data_destroy(struct hist_trigger_data *hist_data,
+			       struct action_data *data)
 {
-	destroy_hist_field(data->onmax.max_var, 0);
-	destroy_hist_field(data->onmax.var, 0);
+	destroy_hist_field(data->track_data.track_var, 0);
+	destroy_hist_field(data->track_data.var_ref, 0);
 
-	kfree(data->onmax.var_str);
+	kfree(data->track_data.var_str);
 
 	action_data_destroy(data);
 }

@@ -3455,25 +3538,24 @@ static void onmax_destroy(struct action_data *data)
 static int action_create(struct hist_trigger_data *hist_data,
 			 struct action_data *data);
 
-static int onmax_create(struct hist_trigger_data *hist_data,
-			struct action_data *data)
+static int track_data_create(struct hist_trigger_data *hist_data,
+			     struct action_data *data)
 {
-	struct hist_field *var_field, *ref_field, *max_var = NULL;
+	struct hist_field *var_field, *ref_field, *track_var = NULL;
 	struct trace_event_file *file = hist_data->event_file;
-	unsigned int var_ref_idx = hist_data->n_var_refs;
-	char *onmax_var_str;
+	char *track_data_var_str;
 	int ret = 0;
 
-	onmax_var_str = data->onmax.var_str;
-	if (onmax_var_str[0] != '$') {
-		hist_err("onmax: For onmax(x), x must be a variable: ", onmax_var_str);
+	track_data_var_str = data->track_data.var_str;
+	if (track_data_var_str[0] != '$') {
+		hist_err("For onmax(x), x must be a variable: ", track_data_var_str);
 		return -EINVAL;
 	}
-	onmax_var_str++;
+	track_data_var_str++;
 
-	var_field = find_target_event_var(hist_data, NULL, NULL, onmax_var_str);
+	var_field = find_target_event_var(hist_data, NULL, NULL, track_data_var_str);
 	if (!var_field) {
-		hist_err("onmax: Couldn't find onmax variable: ", onmax_var_str);
+		hist_err("Couldn't find onmax variable: ", track_data_var_str);
 		return -EINVAL;
 	}

@@ -3481,17 +3563,16 @@ static int onmax_create(struct hist_trigger_data *hist_data,
 	if (!ref_field)
 		return -ENOMEM;
 
-	data->onmax.var = ref_field;
-
-	data->onmax.max_var_ref_idx = var_ref_idx;
+	data->track_data.var_ref = ref_field;
 
-	max_var = create_var(hist_data, file, "max", sizeof(u64), "u64");
-	if (IS_ERR(max_var)) {
-		hist_err("onmax: Couldn't create onmax variable: ", "max");
-		ret = PTR_ERR(max_var);
+	if (data->handler == HANDLER_ONMAX)
+		track_var = create_var(hist_data, file, "__max", sizeof(u64), "u64");
+	if (IS_ERR(track_var)) {
+		hist_err("Couldn't create onmax variable: ", "__max");
+		ret = PTR_ERR(track_var);
 		goto out;
 	}
-	data->onmax.max_var = max_var;
+	data->track_data.track_var = track_var;
 
 	ret = action_create(hist_data, data);
  out:

@@ -3569,7 +3650,18 @@ static int action_parse(char *str, struct action_data *data,
 			goto out;
 
 		if (handler == HANDLER_ONMAX)
-			data->fn = onmax_save;
+			data->track_data.check_val = check_track_val_max;
+		else {
+			hist_err("action parsing: Handler doesn't support action: ", action_name);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		data->track_data.save_val = save_track_val_local;
+		data->track_data.get_val = get_track_val_local;
+		data->track_data.save_data = save_track_data_vars;
+
+		data->fn = ontrack_action;
 
 		data->action = ACTION_SAVE;
 	} else {

@@ -3581,7 +3673,17 @@ static int action_parse(char *str, struct action_data *data,
 				goto out;
 		}
 
-		data->fn = action_trace;
+		if (handler == HANDLER_ONMAX)
+			data->track_data.check_val = check_track_val_max;
+
+		if (handler != HANDLER_ONMATCH) {
+			data->track_data.save_val = save_track_val_local;
+			data->track_data.get_val = get_track_val_local;
+			data->track_data.save_data = action_trace;
+			data->fn = ontrack_action;
+		} else
+			data->fn = action_trace;
+
 		data->action = ACTION_TRACE;
 	}

@@ -3596,24 +3698,25 @@ static int action_parse(char *str, struct action_data *data,
 	return ret;
 }
 
-static struct action_data *onmax_parse(char *str, enum handler_id handler)
+static struct action_data *track_data_parse(struct hist_trigger_data *hist_data,
+					    char *str, enum handler_id handler)
 {
 	struct action_data *data;
-	char *onmax_var_str;
 	int ret = -EINVAL;
+	char *var_str;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return ERR_PTR(-ENOMEM);
 
-	onmax_var_str = strsep(&str, ")");
-	if (!onmax_var_str || !str) {
+	var_str = strsep(&str, ")");
+	if (!var_str || !str) {
 		ret = -EINVAL;
 		goto free;
 	}
 
-	data->onmax.var_str = kstrdup(onmax_var_str, GFP_KERNEL);
-	if (!data->onmax.var_str) {
+	data->track_data.var_str = kstrdup(var_str, GFP_KERNEL);
+	if (!data->track_data.var_str) {
 		ret = -ENOMEM;
 		goto free;
 	}

@@ -3624,7 +3727,7 @@ static struct action_data *onmax_parse(char *str, enum handler_id handler)
  out:
 	return data;
  free:
-	onmax_destroy(data);
+	track_data_destroy(hist_data, data);
 	data = ERR_PTR(ret);
 	goto out;
 }

@@ -4388,7 +4491,7 @@ static void destroy_actions(struct hist_trigger_data *hist_data)
 		if (data->handler == HANDLER_ONMATCH)
 			onmatch_destroy(data);
 		else if (data->handler == HANDLER_ONMAX)
-			onmax_destroy(data);
+			track_data_destroy(hist_data, data);
 		else
 			kfree(data);
 	}

@@ -4417,7 +4520,8 @@ static int parse_actions(struct hist_trigger_data *hist_data)
 		} else if ((len = str_has_prefix(str, "onmax("))) {
 			char *action_str = str + len;
 
-			data = onmax_parse(action_str, HANDLER_ONMAX);
+			data = track_data_parse(hist_data, action_str,
+						HANDLER_ONMAX);
 			if (IS_ERR(data)) {
 				ret = PTR_ERR(data);
 				break;

@@ -4447,7 +4551,7 @@ static int create_actions(struct hist_trigger_data *hist_data)
 			if (ret)
 				break;
 		} else if (data->handler == HANDLER_ONMAX) {
-			ret = onmax_create(hist_data, data);
+			ret = track_data_create(hist_data, data);
 			if (ret)
 				break;
 		} else {

@@ -4469,7 +4573,7 @@ static void print_actions(struct seq_file *m,
 		struct action_data *data = hist_data->actions[i];
 
 		if (data->handler == HANDLER_ONMAX)
-			onmax_print(m, hist_data, elt, data);
+			track_data_print(m, hist_data, elt, data);
 	}
 }

@@ -4494,12 +4598,13 @@ static void print_action_spec(struct seq_file *m,
 	}
 }
 
-static void print_onmax_spec(struct seq_file *m,
-			     struct hist_trigger_data *hist_data,
-			     struct action_data *data)
+static void print_track_data_spec(struct seq_file *m,
+				  struct hist_trigger_data *hist_data,
+				  struct action_data *data)
 {
-	seq_puts(m, ":onmax(");
-	seq_printf(m, "%s", data->onmax.var_str);
+	if (data->handler == HANDLER_ONMAX)
+		seq_puts(m, ":onmax(");
+	seq_printf(m, "%s", data->track_data.var_str);
 	seq_printf(m, ").%s(", data->action_name);
 
 	print_action_spec(m, hist_data, data);

@@ -4557,8 +4662,8 @@ static bool actions_match(struct hist_trigger_data *hist_data,
 				   data_test->match_data.event) != 0)
 				return false;
 		} else if (data->handler == HANDLER_ONMAX) {
-			if (strcmp(data->onmax.var_str,
-				   data_test->onmax.var_str) != 0)
+			if (strcmp(data->track_data.var_str,
+				   data_test->track_data.var_str) != 0)
 				return false;
 		}
 	}

@@ -4578,7 +4683,7 @@ static void print_actions_spec(struct seq_file *m,
 		if (data->handler == HANDLER_ONMATCH)
 			print_onmatch_spec(m, hist_data, data);
 		else if (data->handler == HANDLER_ONMAX)
-			print_onmax_spec(m, hist_data, data);
+			print_track_data_spec(m, hist_data, data);
 	}
 }

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #8 lore raw

PATCH v12 6/16 tracing: Add conditional snapshot

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Currently, tracing snapshots are context-free - they capture the ring buffer contents at the time the tracing_snapshot() function was invoked, and nothing else. Additionally, they're always taken unconditionally - the calling code can decide whether or not to take a snapshot, but the data used to make that decision is kept separately from the snapshot itself.

This change adds the ability to associate with each trace instance some user data, along with an 'update' function that can use that data to determine whether or not to actually take a snapshot. The update function can then update that data along with any other state (as part of the data presumably), if warranted.

Because snapshots are 'global' per-instance, only one user can enable and use a conditional snapshot for any given trace instance. To enable a conditional snapshot (see details in the function and data structure comments), the user calls tracing_snapshot_cond_enable(). Similarly, to disable a conditional snapshot and free it up for other users, tracing_snapshot_cond_disable() should be called.

To actually initiate a conditional snapshot, tracing_snapshot_cond() should be called. tracing_snapshot_cond() will invoke the update() callback, allowing the user to decide whether or not to actually take the snapshot and update the user-defined data associated with the snapshot. If the callback returns 'true', tracing_snapshot_cond() will then actually take the snapshot and return.

This scheme allows for flexibility in snapshot implementations - for example, by implementing slightly different update() callbacks, snapshots can be taken in situations where the user is only interested in taking a snapshot when a new maximum in hit versus when a value changes in any way at all. Future patches will demonstrate both cases.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace.c                | 162 ++++++++++++++++++++++++++++++++++--
 kernel/trace/trace.h                |  56 ++++++++++++-
 kernel/trace/trace_events_trigger.c |   2 +-
 kernel/trace/trace_sched_wakeup.c   |   2 +-
 4 files changed, 211 insertions(+), 11 deletions(-)

kernel/trace/trace.c +155 -7

index 188c4e06c1cc..f936852ebe3d 100644
@@ -894,7 +894,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 EXPORT_SYMBOL_GPL(__trace_bputs);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-void tracing_snapshot_instance(struct trace_array *tr)
+void tracing_snapshot_instance(struct trace_array *tr, void *cond_data)
 {
 	struct tracer *tracer = tr->current_trace;
 	unsigned long flags;

@@ -920,7 +920,7 @@ void tracing_snapshot_instance(struct trace_array *tr)
 	}
 
 	local_irq_save(flags);
-	update_max_tr(tr, current, smp_processor_id());
+	update_max_tr(tr, current, smp_processor_id(), cond_data);
 	local_irq_restore(flags);
 }

@@ -942,10 +942,58 @@ void tracing_snapshot(void)
 {
 	struct trace_array *tr = &global_trace;
 
-	tracing_snapshot_instance(tr);
+	tracing_snapshot_instance(tr, NULL);
 }
 EXPORT_SYMBOL_GPL(tracing_snapshot);
 
+/**
+ * tracing_snapshot_cond - conditionally take a snapshot of the current buffer.
+ * @tr:		The tracing instance to snapshot
+ * @cond_data:	The data to be tested conditionally, and possibly saved
+ *
+ * This is the same as tracing_snapshot() except that the snapshot is
+ * conditional - the snapshot will only happen if the
+ * cond_snapshot.update() implementation receiving the cond_data
+ * returns true, which means that the trace array's cond_snapshot
+ * update() operation used the cond_data to determine whether the
+ * snapshot should be taken, and if it was, presumably saved it along
+ * with the snapshot.
+ */
+void tracing_snapshot_cond(struct trace_array *tr, void *cond_data)
+{
+	tracing_snapshot_instance(tr, cond_data);
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond);
+
+/**
+ * tracing_snapshot_cond_data - get the user data associated with a snapshot
+ * @tr:		The tracing instance
+ *
+ * When the user enables a conditional snapshot using
+ * tracing_snapshot_cond_enable(), the user-defined cond_data is saved
+ * with the snapshot.  This accessor is used to retrieve it.
+ *
+ * Should not be called from cond_snapshot.update(), since it takes
+ * the tr->max_lock lock, which the code calling
+ * cond_snapshot.update() has already done.
+ *
+ * Returns the cond_data associated with the trace array's snapshot.
+ */
+void *tracing_cond_snapshot_data(struct trace_array *tr)
+{
+	void *cond_data = NULL;
+
+	arch_spin_lock(&tr->max_lock);
+
+	if (tr->cond_snapshot)
+		cond_data = tr->cond_snapshot->cond_data;
+
+	arch_spin_unlock(&tr->max_lock);
+
+	return cond_data;
+}
+EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data);
+
 static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
 					struct trace_buffer *size_buf, int cpu_id);
 static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);

@@ -1025,12 +1073,85 @@ void tracing_snapshot_alloc(void)
 	tracing_snapshot();
 }
 EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+
+/**
+ * tracing_snapshot_cond_enable - enable conditional snapshot for an instance
+ * @tr:		The tracing instance
+ * @cond_data:	User data to associate with the snapshot
+ * @update:	Implementation of the cond_snapshot update function
+ *
+ * Check whether the conditional snapshot for the given instance has
+ * already been enabled; if so, return -EBUSY, else create a
+ * cond_snapshot and save the cond_data and update function inside.
+ *
+ * Returns 0 if successful, error otherwise.
+ */
+int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data,
+				 cond_update_fn_t update)
+{
+	struct cond_snapshot *cond_snapshot;
+	int ret = 0;
+
+	cond_snapshot = kzalloc(sizeof(*cond_snapshot), GFP_KERNEL);
+	if (!cond_snapshot)
+		return -ENOMEM;
+
+	cond_snapshot->cond_data = cond_data;
+	cond_snapshot->update = update;
+
+	arch_spin_lock(&tr->max_lock);
+
+	if (tr->cond_snapshot) {
+		kfree(cond_snapshot);
+		ret = -EBUSY;
+	} else
+		tr->cond_snapshot = cond_snapshot;
+
+	arch_spin_unlock(&tr->max_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable);
+
+/**
+ * tracing_snapshot_cond_disable - disable conditional snapshot for an instance
+ * @tr:		The tracing instance
+ *
+ * Check whether the conditional snapshot for the given instance is
+ * enabled; if so, free the cond_snapshot associated with it,
+ * otherwise return -EINVAL.
+ *
+ * Returns 0 if successful, error otherwise.
+ */
+int tracing_snapshot_cond_disable(struct trace_array *tr)
+{
+	int ret = 0;
+
+	arch_spin_lock(&tr->max_lock);
+
+	if (!tr->cond_snapshot)
+		ret = -EINVAL;
+	else {
+		kfree(tr->cond_snapshot);
+		tr->cond_snapshot = NULL;
+	}
+
+	arch_spin_unlock(&tr->max_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable);
 #else
 void tracing_snapshot(void)
 {
 	WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
 }
 EXPORT_SYMBOL_GPL(tracing_snapshot);
+void tracing_snapshot_cond(struct trace_array *tr, void *cond_data)
+{
+	WARN_ONCE(1, "Snapshot feature not enabled, but internal conditional snapshot used");
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond);
 int tracing_alloc_snapshot(void)
 {
 	WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used");

@@ -1043,6 +1164,27 @@ void tracing_snapshot_alloc(void)
 	tracing_snapshot();
 }
 EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+void *tracing_cond_snapshot_data(struct trace_array *tr)
+{
+	WARN_ONCE(1, "Snapshot feature not enabled, but tried to get internal conditional snapshot data");
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data);
+int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update)
+{
+	WARN_ONCE(1, "Snapshot feature not enabled, but tried to enable internal conditional snapshot");
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable);
+int tracing_snapshot_cond_disable(struct trace_array *tr)
+{
+	WARN_ONCE(1, "Snapshot feature not enabled, but tried to disable internal conditional snapshot");
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable);
 #endif /* CONFIG_TRACER_SNAPSHOT */
 
 void tracer_tracing_off(struct trace_array *tr)

@@ -1359,7 +1501,8 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
  * about which task was the cause of this latency.
  */
 void
-update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
+update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
+	      void *cond_data)
 {
 	if (tr->stop_count)
 		return;

@@ -1380,6 +1523,11 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 	else
 		ring_buffer_record_off(tr->max_buffer.buffer);
 
+	if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data)) {
+		arch_spin_unlock(&tr->max_lock);
+		return;
+	}
+
 	swap(tr->trace_buffer.buffer, tr->max_buffer.buffer);
 
 	__update_max_tr(tr, tsk, cpu);

@@ -6503,7 +6651,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		local_irq_disable();
 		/* Now, we're going to swap */
 		if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
-			update_max_tr(tr, current, smp_processor_id());
+			update_max_tr(tr, current, smp_processor_id(), NULL);
 		else
 			update_max_tr_single(tr, current, iter->cpu_file);
 		local_irq_enable();

@@ -7095,7 +7243,7 @@ ftrace_snapshot(unsigned long ip, unsigned long parent_ip,
 		struct trace_array *tr, struct ftrace_probe_ops *ops,
 		void *data)
 {
-	tracing_snapshot_instance(tr);
+	tracing_snapshot_instance(tr, NULL);
 }
 
 static void

@@ -7117,7 +7265,7 @@ ftrace_count_snapshot(unsigned long ip, unsigned long parent_ip,
 		(*count)--;
 	}
 
-	tracing_snapshot_instance(tr);
+	tracing_snapshot_instance(tr, NULL);
 }
 
 static int

kernel/trace/trace.h +54 -2

86 lines not on this page · raw message

kernel/trace/trace_events_trigger.c +1 -1

index 2152d1e530cb..a77102a17046 100644
@@ -1049,7 +1049,7 @@ snapshot_trigger(struct event_trigger_data *data, void *rec,
 	struct trace_event_file *file = data->private_data;
 
 	if (file)
-		tracing_snapshot_instance(file->tr);
+		tracing_snapshot_instance(file->tr, NULL);
 	else
 		tracing_snapshot();
 }

kernel/trace/trace_sched_wakeup.c +1 -1

index 4ea7e6845efb..007c074fe6d6 100644
@@ -482,7 +482,7 @@ probe_wakeup_sched_switch(void *ignore, bool preempt,
 
 	if (likely(!is_tracing_stopped())) {
 		wakeup_trace->max_latency = delta;
-		update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
+		update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu, NULL);
 	}
 
 out_unlock:

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #9 lore raw

PATCH v12 7/16 tracing: Add hist trigger snapshot() action

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add support for hist:handlerXXX($var).snapshot(), which will take a snapshot of the current trace buffer whenever handlerXXX is hit.

As a first user, this also adds snapshot() action support for the onmax() handler i.e. hist:onmax($var).snapshot().

Also, the hist trigger key printing is moved into a separate function so the snapshot() action can print a histogram key outside the histogram display - add and use hist_trigger_print_key() for that purpose.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace.c             |   1 +
 kernel/trace/trace_events_hist.c | 298 +++++++++++++++++++++++++++++++++++++--
 2 files changed, 287 insertions(+), 12 deletions(-)

kernel/trace/trace.c +1 -0

index f936852ebe3d..fcc0f1a963e3 100644
@@ -4900,6 +4900,7 @@ static const char readme_msg[] =
 	"\t    The available actions are:\n\n"
 	"\t        <synthetic_event>(param list)        - generate synthetic event\n"
 	"\t        save(field,...)                      - save current event fields\n"
+	"\t        snapshot()                           - snapshot the trace buffer\n"
 #endif
 ;

kernel/trace/trace_events_hist.c +286 ~~-12~~

412 lines not on this page · raw message

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #10 lore raw

PATCH v12 8/16 tracing: Add hist trigger snapshot() action Documentation

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add Documentation for the hist:handlerXXX($var).snapshot() action.

Signed-off-by Tom Zanussi <[email protected]>

---
 Documentation/trace/histogram.rst | 110 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

Documentation/trace/histogram.rst +110 -0

index 63e522107e59..353317bc3825 100644
@@ -1874,6 +1874,7 @@ The available actions are:
 
   - <synthetic_event_name>(param list)         - generate synthetic event
   - save(field,...)                            - save current event fields
+  - snapshot()                                 - snapshot the trace buffer
 
 The following commonly-used handler.action pairs are available:

@@ -2030,6 +2031,115 @@ The following commonly-used handler.action pairs are available:
             Entries: 2
             Dropped: 0
 
+  - onmax(var).snapshot()
+
+    The 'onmax(var).snapshot()' hist trigger action is invoked
+    whenever the value of 'var' associated with a histogram entry
+    exceeds the current maximum contained in that variable.
+
+    The end result is that a global snapshot of the trace buffer will
+    be saved in the tracing/snapshot file if 'var' exceeds the current
+    maximum for any hist trigger entry.
+
+    Note that in this case the maximum is a global maximum for the
+    current trace instance, which is the maximum across all buckets of
+    the histogram.  The key of the specific trace event that caused
+    the global maximum and the global maximum itself are displayed,
+    along with a message stating that a snapshot has been taken and
+    where to find it.  The user can use the key information displayed
+    to locate the corresponding bucket in the histogram for even more
+    detail.
+
+    As an example the below defines a couple of hist triggers, one for
+    sched_waking and another for sched_switch, keyed on pid.  Whenever
+    a sched_waking event occurs, the timestamp is saved in the entry
+    corresponding to the current pid, and when the scheduler switches
+    back to that pid, the timestamp difference is calculated.  If the
+    resulting latency, stored in wakeup_lat, exceeds the current
+    maximum latency, a snapshot is taken.  As part of the setup, all
+    the scheduler events are also enabled, which are the events that
+    will show up in the snapshot when it is taken at some point:
+
+    # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
+
+    # echo 'hist:keys=pid:ts0=common_timestamp.usecs \
+            if comm=="cyclictest"' >> \
+            /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
+
+    # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \
+            onmax($wakeup_lat).save(next_prio,next_comm,prev_pid,prev_prio, \
+	    prev_comm):onmax($wakeup_lat).snapshot() \
+	    if next_comm=="cyclictest"' >> \
+	    /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
+
+    When the histogram is displayed, for each bucket the max value
+    and the saved values corresponding to the max are displayed
+    following the rest of the fields.
+
+    If a snaphot was taken, there is also a message indicating that,
+    along with the value and event that triggered the global maximum:
+
+    # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
+      { next_pid:       2101 } hitcount:        200
+	max:         52  next_prio:        120  next_comm: cyclictest \
+        prev_pid:          0  prev_prio:        120  prev_comm: swapper/6
+
+      { next_pid:       2103 } hitcount:       1326
+	max:        572  next_prio:         19  next_comm: cyclictest \
+        prev_pid:          0  prev_prio:        120  prev_comm: swapper/1
+
+      { next_pid:       2102 } hitcount:       1982 \
+	max:         74  next_prio:         19  next_comm: cyclictest \
+        prev_pid:          0  prev_prio:        120  prev_comm: swapper/5
+
+    Snapshot taken (see tracing/snapshot).  Details:
+	triggering value { onmax($wakeup_lat) }:        572	\
+	triggered by event with key: { next_pid:       2103 }
+
+    Totals:
+        Hits: 3508
+        Entries: 3
+        Dropped: 0
+
+    In the above case, the event that triggered the global maximum has
+    the key with next_pid == 2103.  If you look at the bucket that has
+    2103 as the key, you'll find the additional values save()'d along
+    with the local maximum for that bucket, which should be the same
+    as the global maximum (since that was the same value that
+    triggered the global snapshot).
+
+    And finally, looking at the snapshot data should show at or near
+    the end the event that triggered the snapshot (in this case you
+    can verify the timestamps between the sched_waking and
+    sched_switch events, which should match the time displayed in the
+    global maximum):
+
+    # cat /sys/kernel/debug/tracing/snapshot
+
+     <...>-2103  [005] d..3   309.873125: sched_switch: prev_comm=cyclictest prev_pid=2103 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120
+     <idle>-0     [005] d.h3   309.873611: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005
+     <idle>-0     [005] dNh4   309.873613: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005
+     <idle>-0     [005] d..3   309.873616: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19
+     <...>-2102  [005] d..3   309.873625: sched_switch: prev_comm=cyclictest prev_pid=2102 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120
+     <idle>-0     [005] d.h3   309.874624: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005
+     <idle>-0     [005] dNh4   309.874626: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005
+     <idle>-0     [005] dNh3   309.874628: sched_waking: comm=cyclictest pid=2103 prio=19 target_cpu=005
+     <idle>-0     [005] dNh4   309.874630: sched_wakeup: comm=cyclictest pid=2103 prio=19 target_cpu=005
+     <idle>-0     [005] d..3   309.874633: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19
+     <idle>-0     [004] d.h3   309.874757: sched_waking: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004
+     <idle>-0     [004] dNh4   309.874762: sched_wakeup: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004
+     <idle>-0     [004] d..3   309.874766: sched_switch: prev_comm=swapper/4 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=gnome-terminal- next_pid=1699 next_prio=120
+ gnome-terminal--1699  [004] d.h2   309.874941: sched_stat_runtime: comm=gnome-terminal- pid=1699 runtime=180706 [ns] vruntime=1126870572 [ns]
+     <idle>-0     [003] d.s4   309.874956: sched_waking: comm=rcu_sched pid=9 prio=120 target_cpu=007
+     <idle>-0     [003] d.s5   309.874960: sched_wake_idle_without_ipi: cpu=7
+     <idle>-0     [003] d.s5   309.874961: sched_wakeup: comm=rcu_sched pid=9 prio=120 target_cpu=007
+     <idle>-0     [007] d..3   309.874963: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=rcu_sched next_pid=9 next_prio=120
+  rcu_sched-9     [007] d..3   309.874973: sched_stat_runtime: comm=rcu_sched pid=9 runtime=13646 [ns] vruntime=22531430286 [ns]
+  rcu_sched-9     [007] d..3   309.874978: sched_switch: prev_comm=rcu_sched prev_pid=9 prev_prio=120 prev_state=R+ ==> next_comm=swapper/7 next_pid=0 next_prio=120
+      <...>-2102  [005] d..4   309.874994: sched_migrate_task: comm=cyclictest pid=2103 prio=19 orig_cpu=5 dest_cpu=1
+      <...>-2102  [005] d..4   309.875185: sched_wake_idle_without_ipi: cpu=1
+     <idle>-0     [001] d..3   309.875200: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2103 next_prio=19
+
 3. User space creating a trigger
 --------------------------------

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #11 lore raw

PATCH v12 9/16 tracing: Add hist trigger onchange() handler

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add support for a hist:onchange($var) handler, similar to the onmax() handler but triggering whenever there's any change in $var, not just a max.

Signed-off-by Tom Zanussi <[email protected]>

---
 kernel/trace/trace.c             |  3 ++-
 kernel/trace/trace_events_hist.c | 58 ++++++++++++++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 9 deletions(-)

kernel/trace/trace.c +2 -1

index fcc0f1a963e3..917677a9bcaa 100644
@@ -4896,7 +4896,8 @@ static const char readme_msg[] =
 	"\t        <handler>.<action>\n\n"
 	"\t    The available handlers are:\n\n"
 	"\t        onmatch(matching.event)  - invoke on addition or update\n"
-	"\t        onmax(var)               - invoke if var exceeds current max\n\n"
+	"\t        onmax(var)               - invoke if var exceeds current max\n"
+	"\t        onchange(var)            - invoke action if var changes\n\n"
 	"\t    The available actions are:\n\n"
 	"\t        <synthetic_event>(param list)        - generate synthetic event\n"
 	"\t        save(field,...)                      - save current event fields\n"

kernel/trace/trace_events_hist.c +50 -8

160 lines not on this page · raw message

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #12 lore raw

PATCH v12 10/16 tracing: Add hist trigger onchange() handler Documentation

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add Documentation for the hist:onchange($var) handler.

Signed-off-by Tom Zanussi <[email protected]>

---
 Documentation/trace/histogram.rst | 98 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)

Documentation/trace/histogram.rst +98 -0

index 353317bc3825..79476c906b1a 100644
@@ -1869,6 +1869,7 @@ The available handlers are:
 
   - onmatch(matching.event)    - invoke action on any addition or update
   - onmax(var)                 - invoke action if var exceeds current max
+  - onchange(var)              - invoke action if var changes
 
 The available actions are:

@@ -2140,6 +2141,103 @@ The following commonly-used handler.action pairs are available:
       <...>-2102  [005] d..4   309.875185: sched_wake_idle_without_ipi: cpu=1
      <idle>-0     [001] d..3   309.875200: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2103 next_prio=19
 
+  - onchange(var).save(field,..	.)
+
+    The 'onchange(var).save(field,...)' hist trigger action is invoked
+    whenever the value of 'var' associated with a histogram entry
+    changes.
+
+    The end result is that the trace event fields specified as the
+    onchange.save() params will be saved if 'var' changes for that
+    hist trigger entry.  This allows context from the event that
+    changed the value to be saved for later reference.  When the
+    histogram is displayed, additional fields displaying the saved
+    values will be printed.
+
+  - onchange(var).snapshot()
+
+    The 'onchange(var).snapshot()' hist trigger action is invoked
+    whenever the value of 'var' associated with a histogram entry
+    changes.
+
+    The end result is that a global snapshot of the trace buffer will
+    be saved in the tracing/snapshot file if 'var' changes for any
+    hist trigger entry.
+
+    Note that in this case the changed value is a global variable
+    associated withe current trace instance.  The key of the specific
+    trace event that caused the value to change and the global value
+    itself are displayed, along with a message stating that a snapshot
+    has been taken and where to find it.  The user can use the key
+    information displayed to locate the corresponding bucket in the
+    histogram for even more detail.
+
+    As an example the below defines a hist trigger on the tcp_probe
+    event, keyed on dport.  Whenever a tcp_probe event occurs, the
+    cwnd field is checked against the current value stored in the
+    $cwnd variable.  If the value has changed, a snapshot is taken.
+    As part of the setup, all the scheduler and tcp events are also
+    enabled, which are the events that will show up in the snapshot
+    when it is taken at some point:
+
+    # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
+    # echo 1 > /sys/kernel/debug/tracing/events/tcp/enable
+
+    # echo 'hist:keys=dport:cwnd=snd_cwnd: \
+            onchange($cwnd).save(snd_wnd,srtt,rcv_wnd): \
+	    onchange($cwnd).snapshot()' >> \
+	    /sys/kernel/debug/tracing/events/tcp/tcp_probe/trigger
+
+    When the histogram is displayed, for each bucket the tracked value
+    and the saved values corresponding to that value are displayed
+    following the rest of the fields.
+
+    If a snaphot was taken, there is also a message indicating that,
+    along with the value and event that triggered the snapshot:
+
+    # cat /sys/kernel/debug/tracing/events/tcp/tcp_probe/hist
+      { dport:       1521 } hitcount:          8
+	changed:         10  snd_wnd:      35456  srtt:     154262  rcv_wnd:      42112
+
+      { dport:         80 } hitcount:         23
+	changed:         10  snd_wnd:      28960  srtt:      19604  rcv_wnd:      29312
+
+      { dport:       9001 } hitcount:        172
+	changed:         10  snd_wnd:      48384  srtt:     260444  rcv_wnd:      55168
+
+      { dport:        443 } hitcount:        211
+	changed:         10  snd_wnd:      26960  srtt:      17379  rcv_wnd:      28800
+
+    Snapshot taken (see tracing/snapshot).  Details:
+        triggering value { onchange($cwnd) }:         10
+        triggered by event with key: { dport:         80 }
+
+    Totals:
+        Hits: 414
+        Entries: 4
+        Dropped: 0
+
+    In the above case, the event that triggered the snapshot has the
+    key with dport == 80.  If you look at the bucket that has 80 as
+    the key, you'll find the additional values save()'d along with the
+    changed value for that bucket, which should be the same as the
+    global changed value (since that was the same value that triggered
+    the global snapshot).
+
+    And finally, looking at the snapshot data should show at or near
+    the end the event that triggered the snapshot:
+
+    # cat /sys/kernel/debug/tracing/snapshot
+
+       gnome-shell-1261  [006] dN.3    49.823113: sched_stat_runtime: comm=gnome-shell pid=1261 runtime=49347 [ns] vruntime=1835730389 [ns]
+     kworker/u16:4-773   [003] d..3    49.823114: sched_switch: prev_comm=kworker/u16:4 prev_pid=773 prev_prio=120 prev_state=R+ ==> next_comm=kworker/3:2 next_pid=135 next_prio=120
+       gnome-shell-1261  [006] d..3    49.823114: sched_switch: prev_comm=gnome-shell prev_pid=1261 prev_prio=120 prev_state=R+ ==> next_comm=kworker/6:2 next_pid=387 next_prio=120
+       kworker/3:2-135   [003] d..3    49.823118: sched_stat_runtime: comm=kworker/3:2 pid=135 runtime=5339 [ns] vruntime=17815800388 [ns]
+       kworker/6:2-387   [006] d..3    49.823120: sched_stat_runtime: comm=kworker/6:2 pid=387 runtime=9594 [ns] vruntime=14589605367 [ns]
+       kworker/6:2-387   [006] d..3    49.823122: sched_switch: prev_comm=kworker/6:2 prev_pid=387 prev_prio=120 prev_state=R+ ==> next_comm=gnome-shell next_pid=1261 next_prio=120
+       kworker/3:2-135   [003] d..3    49.823123: sched_switch: prev_comm=kworker/3:2 prev_pid=135 prev_prio=120 prev_state=T ==> next_comm=swapper/3 next_pid=0 next_prio=120
+            <idle>-0     [004] ..s7    49.823798: tcp_probe: src=10.0.0.10:54326 dest=23.215.104.193:80 mark=0x0 length=32 snd_nxt=0xe3ae2ff5 snd_una=0xe3ae2ecd snd_cwnd=10 ssthresh=2147483647 snd_wnd=28960 srtt=19604 rcv_wnd=29312
+
 3. User space creating a trigger
 --------------------------------

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #13 lore raw

PATCH v12 11/16 tracing: Add alternative synthetic event trace action syntax

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add a 'trace(synthetic_event_name, params)' alternative to synthetic_event_name(params).

Currently, the syntax used for generating synthetic events is to invoke synthetic_event_name(params) i.e. use the synthetic event name as a function call.

Users requested a new form that more explicitly shows that the synthetic event is in effect being traced. In this version, a new 'trace()' keyword is used, and the synthetic event name is passed in as the first argument.

In addition, for the sake of consistency with other actions, change the documention to emphasize the trace() form over the function-call form, which remains documented as equivalent.

Signed-off-by Tom Zanussi <[email protected]>

---
 Documentation/trace/histogram.rst | 54 +++++++++++++++++++++++++++------------
 kernel/trace/trace.c              |  2 +-
 kernel/trace/trace_events_hist.c  | 42 +++++++++++++++++++++++++++---
 3 files changed, 76 insertions(+), 22 deletions(-)

Documentation/trace/histogram.rst +37 ~~-17~~

index 79476c906b1a..0ea59d45aef1 100644
@@ -1873,31 +1873,45 @@ The available handlers are:
 
 The available actions are:
 
-  - <synthetic_event_name>(param list)         - generate synthetic event
+  - trace(<synthetic_event_name>,param list)   - generate synthetic event
   - save(field,...)                            - save current event fields
   - snapshot()                                 - snapshot the trace buffer
 
 The following commonly-used handler.action pairs are available:
 
-  - onmatch(matching.event).<synthetic_event_name>(param list)
+  - onmatch(matching.event).trace(<synthetic_event_name>,param list)
 
-    The 'onmatch(matching.event).<synthetic_event_name>(params)' hist
-    trigger action is invoked whenever an event matches and the
-    histogram entry would be added or updated.  It causes the named
-    synthetic event to be generated with the values given in the
+    The 'onmatch(matching.event).trace(<synthetic_event_name>,param
+    list)' hist trigger action is invoked whenever an event matches
+    and the histogram entry would be added or updated.  It causes the
+    named synthetic event to be generated with the values given in the
     'param list'.  The result is the generation of a synthetic event
     that consists of the values contained in those variables at the
-    time the invoking event was hit.
-
-    The 'param list' consists of one or more parameters which may be
-    either variables or fields defined on either the 'matching.event'
-    or the target event.  The variables or fields specified in the
-    param list may be either fully-qualified or unqualified.  If a
-    variable is specified as unqualified, it must be unique between
-    the two events.  A field name used as a param can be unqualified
-    if it refers to the target event, but must be fully qualified if
-    it refers to the matching event.  A fully-qualified name is of the
-    form 'system.event_name.$var_name' or 'system.event_name.field'.
+    time the invoking event was hit.  For example, if the synthetic
+    event name is 'wakeup_latency', a wakeup_latency event is
+    generated using onmatch(event).trace(wakeup_latency,arg1,arg2).
+
+    There is also an equivalent alternative form available for
+    generating synthetic events.  In this form, the synthetic event
+    name is used as if it were a function name.  For example, using
+    the 'wakeup_latency' synthetic event name again, the
+    wakeup_latency event would be generated by invoking it as if it
+    were a function call, with the event field values passed in as
+    arguments: onmatch(event).wakeup_latency(arg1,arg2).  The syntax
+    for this form is:
+
+      onmatch(matching.event).<synthetic_event_name>(param list)
+
+    In either case, the 'param list' consists of one or more
+    parameters which may be either variables or fields defined on
+    either the 'matching.event' or the target event.  The variables or
+    fields specified in the param list may be either fully-qualified
+    or unqualified.  If a variable is specified as unqualified, it
+    must be unique between the two events.  A field name used as a
+    param can be unqualified if it refers to the target event, but
+    must be fully qualified if it refers to the matching event.  A
+    fully-qualified name is of the form 'system.event_name.$var_name'
+    or 'system.event_name.field'.
 
     The 'matching.event' specification is simply the fully qualified
     event name of the event that matches the target event for the

@@ -1928,6 +1942,12 @@ The following commonly-used handler.action pairs are available:
               wakeup_new_test($testpid) if comm=="cyclictest"' >> \
               /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger
 
+    Or, equivalently, using the 'trace' keyword syntax:
+
+    # echo 'hist:keys=$testpid:testpid=pid:onmatch(sched.sched_wakeup_new).\
+            trace(wakeup_new_test,$testpid) if comm=="cyclictest"' >> \
+            /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger
+
     Creating and displaying a histogram based on those events is now
     just a matter of using the fields and new synthetic event in the
     tracing/events/synthetic directory, as usual::

kernel/trace/trace.c +1 -1

index 917677a9bcaa..8c220d97c214 100644
@@ -4899,7 +4899,7 @@ static const char readme_msg[] =
 	"\t        onmax(var)               - invoke if var exceeds current max\n"
 	"\t        onchange(var)            - invoke action if var changes\n\n"
 	"\t    The available actions are:\n\n"
-	"\t        <synthetic_event>(param list)        - generate synthetic event\n"
+	"\t        trace(<synthetic_event>,param list)  - generate synthetic event\n"
 	"\t        save(field,...)                      - save current event fields\n"
 	"\t        snapshot()                           - snapshot the trace buffer\n"
 #endif

kernel/trace/trace_events_hist.c +38 -4

102 lines not on this page · raw message

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #14 lore raw

PATCH v12 12/16 tracing: Add SPDX license GPL-2.0 license identifier to inter-event testcases

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Apparently this directory was missed in the license cleanup process - add the missing identifiers to the trigger/inter-event test cases.

Signed-off-by Tom Zanussi <[email protected]>

---
 .../ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc  | 1 +
 .../ftrace/test.d/trigger/inter-event/trigger-field-variable-support.tc  | 1 +
 .../test.d/trigger/inter-event/trigger-inter-event-combined-hist.tc      | 1 +
 .../ftrace/test.d/trigger/inter-event/trigger-multi-actions-accept.tc    | 1 +
 .../ftrace/test.d/trigger/inter-event/trigger-onmatch-action-hist.tc     | 1 +
 .../test.d/trigger/inter-event/trigger-onmatch-onmax-action-hist.tc      | 1 +
 .../ftrace/test.d/trigger/inter-event/trigger-onmax-action-hist.tc       | 1 +
 .../test.d/trigger/inter-event/trigger-synthetic-event-createremove.tc   | 1 +
 8 files changed, 8 insertions(+)

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc +1 -0

index 401104344593..9912616a8672 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test extended error support

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-field-variable-support.tc +1 -0

index f59b2a9a1f22..77be6e1f6e7b 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test field variable support
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-inter-event-combined-hist.tc +1 -0

index 524d9ce361e2..f3eb8aacec0e 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event combined histogram trigger
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-multi-actions-accept.tc +1 -0

index 4ddc546771b5..d281f056f980 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test multiple actions on hist trigger
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmatch-action-hist.tc +1 -0

index 39fb65b0cd9f..a708f0e7858a 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmatch action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmatch-onmax-action-hist.tc +1 -0

index 81ab3939c96a..dfce6932d8be 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmatch-onmax action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmax-action-hist.tc +1 -0

index 1180ab5f0845..0035995c2194 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmax action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-synthetic-event-createremove.tc +1 -0

index 41128219231a..df44b14724a4 100644
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test synthetic event create remove
 
 fail() { #msg

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #15 lore raw

PATCH v12 13/16 tracing: Add hist trigger snapshot() action test case

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add a test case verifying the basic functionality of the hist:snapshot() action.

Signed-off-by Tom Zanussi <[email protected]>

Acked-by Masami Hiramatsu <[email protected]>

---
 .../inter-event/trigger-snapshot-action-hist.tc    | 43 ++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-snapshot-action-hist.tc

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-snapshot-action-hist.tc new file +43 -0

new file mode 100644
index 000000000000..18fff69fc433
@@ -0,0 +1,43 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test inter-event histogram trigger snapshot action
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+if [ ! -f set_event ]; then
+    echo "event tracing is not supported"
+    exit_unsupported
+fi
+
+if [ ! -f snapshot ]; then
+    echo "snapshot is not supported"
+    exit_unsupported
+fi
+
+grep -q "onchange(var)" README || exit_unsupported # version issue
+
+grep -q "snapshot()" README || exit_unsupported # version issue
+
+echo "Test snapshot action"
+
+echo 1 > /sys/kernel/debug/tracing/events/sched/enable
+
+echo 'hist:keys=comm:newprio=prio:onchange($newprio).save(comm,prio):onchange($newprio).snapshot() if comm=="ping"' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
+
+ping $LOCALHOST -c 3
+nice -n 1 ping $LOCALHOST -c 3
+
+echo 0 > tracing_on
+
+if ! grep -q "changed:" events/sched/sched_waking/hist; then
+    fail "Failed to create onchange action inter-event histogram"
+fi
+
+if ! grep -q "comm=ping" snapshot; then
+    fail "Failed to create snapshot action inter-event histogram"
+fi
+
+exit 0

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #16 lore raw

PATCH v12 14/16 tracing: Add hist trigger onchange() handler test case

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add a test case verifying the basic functionality of the hist:onchange($var) handler.

Signed-off-by Tom Zanussi <[email protected]>

Acked-by Masami Hiramatsu <[email protected]>

---
 .../inter-event/trigger-onchange-action-hist.tc    | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onchange-action-hist.tc

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onchange-action-hist.tc new file +28 -0

new file mode 100644
index 000000000000..064a284e4e75
@@ -0,0 +1,28 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test inter-event histogram trigger onchange action
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+if [ ! -f set_event ]; then
+    echo "event tracing is not supported"
+    exit_unsupported
+fi
+
+grep -q "onchange(var)" README || exit_unsupported # version issue
+
+echo "Test onchange action"
+
+echo 'hist:keys=comm:newprio=prio:onchange($newprio).save(comm,prio) if comm=="ping"' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
+
+ping $LOCALHOST -c 3
+nice -n 1 ping $LOCALHOST -c 3
+
+if ! grep -q "changed:" events/sched/sched_waking/hist; then
+    fail "Failed to create onchange action inter-event histogram"
+fi
+
+exit 0

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:05 UTC #17 lore raw

PATCH v12 15/16 tracing: Add alternative synthetic event trace action test case

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add a test case for the alternative trace(<synthetic_event, params) synthetic event generation syntax.

Signed-off-by Tom Zanussi <[email protected]>

---
 .../inter-event/trigger-trace-action-hist.tc       | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-trace-action-hist.tc

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-trace-action-hist.tc new file +42 -0

new file mode 100644
index 000000000000..8021d60aafec
@@ -0,0 +1,42 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test inter-event histogram trigger trace action
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+if [ ! -f set_event ]; then
+    echo "event tracing is not supported"
+    exit_unsupported
+fi
+
+if [ ! -f synthetic_events ]; then
+    echo "synthetic event is not supported"
+    exit_unsupported
+fi
+
+grep -q "trace(<synthetic_event>" README || exit_unsupported # version issue
+
+echo "Test create synthetic event"
+
+echo 'wakeup_latency  u64 lat pid_t pid char comm[16]' > synthetic_events
+if [ ! -d events/synthetic/wakeup_latency ]; then
+    fail "Failed to create wakeup_latency synthetic event"
+fi
+
+echo "Test create histogram for synthetic event using trace action"
+echo "Test histogram variables,simple expression support and trace action"
+
+echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="ping"' > events/sched/sched_wakeup/trigger
+echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_wakeup).trace(wakeup_latency,$wakeup_lat,next_pid,next_comm) if next_comm=="ping"' > events/sched/sched_switch/trigger
+echo 'hist:keys=comm,pid,lat:wakeup_lat=lat:sort=lat' > events/synthetic/wakeup_latency/trigger
+
+ping $LOCALHOST -c 5
+
+if ! grep -q "ping" events/synthetic/wakeup_latency/hist; then
+    fail "Failed to create trace action inter-event histogram"
+fi
+
+exit 0

Signature · 1 line

2.14.1

Tom Zanussi

author

2019-01-15 22:06 UTC #18 lore raw

PATCH v12 16/16 tracing: Add hist trigger action 'expected fail' test case

In reply to Tom Zanussi

From: Tom Zanussi <[email protected]>

Add a test case verifying that basic action combinations fail as expected.

Signed-off-by Tom Zanussi <[email protected]>

---
 .../inter-event/trigger-action-hist-xfail.tc       | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-action-hist-xfail.tc

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-action-hist-xfail.tc new file +30 -0

new file mode 100644
index 000000000000..1221240f8cf6
@@ -0,0 +1,30 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test inter-event histogram trigger expected fail actions
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+if [ ! -f set_event ]; then
+    echo "event tracing is not supported"
+    exit_unsupported
+fi
+
+if [ ! -f snapshot ]; then
+    echo "snapshot is not supported"
+    exit_unsupported
+fi
+
+grep -q "snapshot()" README || exit_unsupported # version issue
+
+echo "Test expected snapshot action failure"
+
+echo 'hist:keys=comm:onmatch(sched.sched_wakeup).snapshot()' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger && exit_fail
+
+echo "Test expected save action failure"
+
+echo 'hist:keys=comm:onmatch(sched.sched_wakeup).save(comm,prio)' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger && exit_fail
+
+exit_xfail

Signature · 1 line

2.14.1

Namhyung Kim

2019-01-16 06:43 UTC #19 lore raw

In reply to Tom Zanussi

Hi Tom,

Quoted 11 lines · Tom Zanussi

From: Tom Zanussi <[email protected]>
Hi,
This is v12 of the hist trigger snapshot and onchange additions patchset.
It addresses some comments from Namhyung regarding the 'tracing: Add alternative synthetic event trace action syntax' patch to remove parens and change the documentation to emphasize the trace() form of the synthetic event generation command.

I got below from the following test:

  # echo 'hist:key=comm:p=prio:onchange($p).snapshot()' > \
    events/sched/sched_waking/trigger

  # echo 1 > snapshot

Thanks,
Namhyung

[ 2217.403818] BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1369
[ 2217.406394] in_atomic(): 0, irqs_disabled(): 1, pid: 65, name: sh
[ 2217.406394] 3 locks held by sh/65:
[ 2217.406394]  #0: 000000006082fdb2 (sb_writers#5){.+.+}, at: vfs_write+0x109/0x130
[ 2217.406394]  #1: 000000003e4def73 (trace_types_lock){+.+.}, at: tracing_snapshot_write+0x93/0x170
[ 2217.406394]  #2: 0000000050fd4c4a (&mm->mmap_sem){++++}, at: __do_page_fault+0x19a/0x4e0
[ 2217.406394] irq event stamp: 173368
[ 2217.406394] hardirqs last  enabled at (173367): [<ffffffff815369e9>] _raw_spin_unlock_irq+0x29/0x40
[ 2217.406394] hardirqs last disabled at (173368): [<ffffffff811079b2>] tracing_snapshot_write+0xf2/0x170
[ 2217.406394] softirqs last  enabled at (173258): [<ffffffff81800288>] __do_softirq+0x288/0x47c
[ 2217.406394] softirqs last disabled at (173253): [<ffffffff8105a682>] irq_exit+0x62/0xa0
[ 2217.406394] CPU: 0 PID: 65 Comm: sh Not tainted 4.20.0-rc3+ #259
[ 2217.406394] Call Trace:
[ 2217.406394]  dump_stack+0x67/0x90
[ 2217.406394]  ___might_sleep.cold.5+0x9f/0xb1
[ 2217.406394]  __do_page_fault+0x1b7/0x4e0
[ 2217.406394]  page_fault+0x1e/0x30
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87 c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4 48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84 c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX: ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09: 0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12: 0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15: 0000000000000000
[ 2217.406394]  update_max_tr+0x82/0xe0
[ 2217.406394]  tracing_snapshot_write+0x15c/0x170
[ 2217.406394]  __vfs_write+0x36/0x180
[ 2217.406394]  ? rcu_read_lock_sched_held+0x76/0x80
[ 2217.406394]  ? rcu_sync_lockdep_assert+0x2e/0x60
[ 2217.406394]  ? __sb_start_write+0x14c/0x1b0
[ 2217.406394]  ? vfs_write+0x109/0x130
[ 2217.406394]  vfs_write+0xb7/0x130
[ 2217.406394]  ksys_write+0x52/0xc0
[ 2217.406394]  do_syscall_64+0x50/0x180
[ 2217.406394]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 2217.406394] RIP: 0033:0x7f9bc3170818
[ 2217.406394] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 25 6d 0d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55
[ 2217.406394] RSP: 002b:00007ffdef643888 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 2217.406394] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f9bc3170818
[ 2217.406394] RDX: 0000000000000002 RSI: 00005651d6bf0db0 RDI: 0000000000000001
[ 2217.406394] RBP: 00005651d6bf0db0 R08: 000000000000000a R09: 00007ffdef643410
[ 2217.406394] R10: 000000000000000a R11: 0000000000000246 R12: 00007f9bc32435c0
[ 2217.406394] R13: 0000000000000002 R14: 00007f9bc323e5c0 R15: 0000000000000002

[ 2217.406394] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[ 2217.406394] PGD 0 P4D 0 
[ 2217.406394] Oops: 0000 [#1] SMP PTI
[ 2217.406394] CPU: 0 PID: 65 Comm: sh Tainted: G        W         4.20.0-rc3+ #259
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87 c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4 48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84 c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX: ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09: 0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12: 0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15: 0000000000000000
[ 2217.406394] FS:  00007f9bc3013b80(0000) GS:ffff88803e400000(0000) knlGS:0000000000000000
[ 2217.406394] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2217.406394] CR2: 0000000000000000 CR3: 000000003d138001 CR4: 0000000000060eb0
[ 2217.406394] Call Trace:
[ 2217.406394]  update_max_tr+0x82/0xe0
[ 2217.406394]  tracing_snapshot_write+0x15c/0x170
[ 2217.406394]  __vfs_write+0x36/0x180
[ 2217.406394]  ? rcu_read_lock_sched_held+0x76/0x80
[ 2217.406394]  ? rcu_sync_lockdep_assert+0x2e/0x60
[ 2217.406394]  ? __sb_start_write+0x14c/0x1b0
[ 2217.406394]  ? vfs_write+0x109/0x130
[ 2217.406394]  vfs_write+0xb7/0x130
[ 2217.406394]  ksys_write+0x52/0xc0
[ 2217.406394]  do_syscall_64+0x50/0x180
[ 2217.406394]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 2217.406394] RIP: 0033:0x7f9bc3170818
[ 2217.406394] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 25 6d 0d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55
[ 2217.406394] RSP: 002b:00007ffdef643888 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 2217.406394] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f9bc3170818
[ 2217.406394] RDX: 0000000000000002 RSI: 00005651d6bf0db0 RDI: 0000000000000001
[ 2217.406394] RBP: 00005651d6bf0db0 R08: 000000000000000a R09: 00007ffdef643410
[ 2217.406394] R10: 000000000000000a R11: 0000000000000246 R12: 00007f9bc32435c0
[ 2217.406394] R13: 0000000000000002 R14: 00007f9bc323e5c0 R15: 0000000000000002
[ 2217.406394] Modules linked in:
[ 2217.406394] CR2: 0000000000000000
[ 2217.406394] ---[ end trace 832915071760c624 ]---
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87 c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4 48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84 c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX: ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09: 0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12: 0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15: 0000000000000000
[ 2217.406394] FS:  00007f9bc3013b80(0000) GS:ffff88803e400000(0000) knlGS:0000000000000000
[ 2217.406394] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2217.406394] CR2: 0000000000000000 CR3: 000000003d138001 CR4: 0000000000060eb0

Tom Zanussi

author

2019-01-16 19:02 UTC #20 lore raw

Hi Namhyung,

Quoted 17 lines · Namhyung Kim

Hi Tom,
Quoted 7 lines · Tom Zanussi
From: Tom Zanussi <[email protected]>
Hi,
This is v12 of the hist trigger snapshot and onchange additions patchset.
Quoted 6 lines
It addresses some comments from Namhyung regarding the 'tracing:
Add
alternative synthetic event trace action syntax' patch to remove parens and change the documentation to emphasize the trace() form of
the synthetic event generation command.

Quoted 7 lines

I got below from the following test:

  # echo 'hist:key=comm:p=prio:onchange($p).snapshot()' > \
    events/sched/sched_waking/trigger

  # echo 1 > snapshot

Thanks for reporting this. If there's a snapshot trigger in effect, attempting to take a snapshot from the command-line should really return -EBUSY - I'll update the snapshot code to do that.

Tom

Quoted 156 lines

Thanks,
Namhyung

[ 2217.403818] BUG: sleeping function called from invalid context at
arch/x86/mm/fault.c:1369
[ 2217.406394] in_atomic(): 0, irqs_disabled(): 1, pid: 65, name: sh
[ 2217.406394] 3 locks held by sh/65:
[ 2217.406394]  #0: 000000006082fdb2 (sb_writers#5){.+.+}, at:
vfs_write+0x109/0x130
[ 2217.406394]  #1: 000000003e4def73 (trace_types_lock){+.+.}, at:
tracing_snapshot_write+0x93/0x170
[ 2217.406394]  #2: 0000000050fd4c4a (&mm->mmap_sem){++++}, at:
__do_page_fault+0x19a/0x4e0
[ 2217.406394] irq event stamp: 173368
[ 2217.406394] hardirqs last  enabled at (173367):
[<ffffffff815369e9>] _raw_spin_unlock_irq+0x29/0x40
[ 2217.406394] hardirqs last disabled at (173368):
[<ffffffff811079b2>] tracing_snapshot_write+0xf2/0x170
[ 2217.406394] softirqs last  enabled at (173258):
[<ffffffff81800288>] __do_softirq+0x288/0x47c
[ 2217.406394] softirqs last disabled at (173253):
[<ffffffff8105a682>] irq_exit+0x62/0xa0
[ 2217.406394] CPU: 0 PID: 65 Comm: sh Not tainted 4.20.0-rc3+ #259
[ 2217.406394] Call Trace:
[ 2217.406394]  dump_stack+0x67/0x90
[ 2217.406394]  ___might_sleep.cold.5+0x9f/0xb1
[ 2217.406394]  __do_page_fault+0x1b7/0x4e0
[ 2217.406394]  page_fault+0x1e/0x30
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87
c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4
48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84
c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX:
ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09:
0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12:
0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15:
0000000000000000
[ 2217.406394]  update_max_tr+0x82/0xe0
[ 2217.406394]  tracing_snapshot_write+0x15c/0x170
[ 2217.406394]  __vfs_write+0x36/0x180
[ 2217.406394]  ? rcu_read_lock_sched_held+0x76/0x80
[ 2217.406394]  ? rcu_sync_lockdep_assert+0x2e/0x60
[ 2217.406394]  ? __sb_start_write+0x14c/0x1b0
[ 2217.406394]  ? vfs_write+0x109/0x130
[ 2217.406394]  vfs_write+0xb7/0x130
[ 2217.406394]  ksys_write+0x52/0xc0
[ 2217.406394]  do_syscall_64+0x50/0x180
[ 2217.406394]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 2217.406394] RIP: 0033:0x7f9bc3170818
[ 2217.406394] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00
00 00 f3 0f 1e fa 48 8d 05 25 6d 0d 00 8b 00 85 c0 75 17 b8 01 00 00
00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49
89 d4 55
[ 2217.406394] RSP: 002b:00007ffdef643888 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
[ 2217.406394] RAX: ffffffffffffffda RBX: 0000000000000002 RCX:
00007f9bc3170818
[ 2217.406394] RDX: 0000000000000002 RSI: 00005651d6bf0db0 RDI:
0000000000000001
[ 2217.406394] RBP: 00005651d6bf0db0 R08: 000000000000000a R09:
00007ffdef643410
[ 2217.406394] R10: 000000000000000a R11: 0000000000000246 R12:
00007f9bc32435c0
[ 2217.406394] R13: 0000000000000002 R14: 00007f9bc323e5c0 R15:

0000000000000002

[ 2217.406394] BUG: unable to handle kernel NULL pointer dereference
at 0000000000000000
[ 2217.406394] PGD 0 P4D 0 
[ 2217.406394] Oops: 0000 [#1] SMP PTI
[ 2217.406394] CPU: 0 PID: 65 Comm: sh Tainted:
G        W         4.20.0-rc3+ #259
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87
c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4
48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84
c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX:
ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09:
0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12:
0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15:
0000000000000000
[ 2217.406394] FS:  00007f9bc3013b80(0000) GS:ffff88803e400000(0000)
knlGS:0000000000000000
[ 2217.406394] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2217.406394] CR2: 0000000000000000 CR3: 000000003d138001 CR4:
0000000000060eb0
[ 2217.406394] Call Trace:
[ 2217.406394]  update_max_tr+0x82/0xe0
[ 2217.406394]  tracing_snapshot_write+0x15c/0x170
[ 2217.406394]  __vfs_write+0x36/0x180
[ 2217.406394]  ? rcu_read_lock_sched_held+0x76/0x80
[ 2217.406394]  ? rcu_sync_lockdep_assert+0x2e/0x60
[ 2217.406394]  ? __sb_start_write+0x14c/0x1b0
[ 2217.406394]  ? vfs_write+0x109/0x130
[ 2217.406394]  vfs_write+0xb7/0x130
[ 2217.406394]  ksys_write+0x52/0xc0
[ 2217.406394]  do_syscall_64+0x50/0x180
[ 2217.406394]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 2217.406394] RIP: 0033:0x7f9bc3170818
[ 2217.406394] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00
00 00 f3 0f 1e fa 48 8d 05 25 6d 0d 00 8b 00 85 c0 75 17 b8 01 00 00
00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49
89 d4 55
[ 2217.406394] RSP: 002b:00007ffdef643888 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
[ 2217.406394] RAX: ffffffffffffffda RBX: 0000000000000002 RCX:
00007f9bc3170818
[ 2217.406394] RDX: 0000000000000002 RSI: 00005651d6bf0db0 RDI:
0000000000000001
[ 2217.406394] RBP: 00005651d6bf0db0 R08: 000000000000000a R09:
00007ffdef643410
[ 2217.406394] R10: 000000000000000a R11: 0000000000000246 R12:
00007f9bc32435c0
[ 2217.406394] R13: 0000000000000002 R14: 00007f9bc323e5c0 R15:
0000000000000002
[ 2217.406394] Modules linked in:
[ 2217.406394] CR2: 0000000000000000
[ 2217.406394] ---[ end trace 832915071760c624 ]---
[ 2217.406394] RIP: 0010:cond_snapshot_update+0x26/0xa0
[ 2217.406394] Code: ff ff 66 90 55 48 89 e5 41 55 41 54 53 48 8b 87
c8 16 00 00 48 8b 18 48 83 e4 f0 48 85 db 74 20 48 8b 43 50 49 89 f4
48 8b 3b <48> 8b 36 48 8b 80 e0 00 00 00 e8 1b 43 6e 00 41 89 c5 84
c0 75 11
[ 2217.406394] RSP: 0018:ffffc90000163dc0 EFLAGS: 00010082
[ 2217.406394] RAX: ffff88803dc07000 RBX: ffff88803df7b720 RCX:
ffff88800008e408
[ 2217.406394] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000078
[ 2217.406394] RBP: ffffc90000163de0 R08: 0000000000000000 R09:
0000000000000001
[ 2217.406394] R10: ffffc90000163e18 R11: 0000000000000002 R12:
0000000000000000
[ 2217.406394] R13: 0000000000000000 R14: ffffc90000163f08 R15:
0000000000000000
[ 2217.406394] FS:  00007f9bc3013b80(0000) GS:ffff88803e400000(0000)
knlGS:0000000000000000
[ 2217.406394] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2217.406394] CR2: 0000000000000000 CR3: 000000003d138001 CR4:

0000000000060eb0