tracing: More updates for 4.7

PATCH New Steven Rostedt 1 participant 6 messages Apr 27, 2016 Tracing

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Steven Rostedt

author maintainer

2016-04-27 16:34 UTC #0 lore raw

cover tracing: More updates for 4.7

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
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Head SHA1: 4afe6495e5cb3c352d95f07512cbb227e607e2ce

Dan Carpenter (1):
tracing: checking for NULL instead of IS_ERR()

Steven Rostedt (Red Hat) (1):
tracing: Do not inherit event-fork option for instances

Tom Zanussi (2):
tracing: Add check for NULL event field when creating hist field
tracing: Handle tracing_map_alloc_elts() error path correctly

Wang Xiaoqiang (1):
tracing: Don't use the address of the buffer array name in copy_from_user

----

 kernel/trace/trace.c             | 17 +++++++++++++----
 kernel/trace/trace_events_hist.c |  3 +++
 kernel/trace/tracing_map.c       | 10 +++++++---
 3 files changed, 23 insertions(+), 7 deletions(-)

Steven Rostedt

author maintainer

2016-04-27 16:32 UTC #1 lore raw

PATCH 1/5 tracing: Do not inherit event-fork option for instances

From: "Steven Rostedt (Red Hat)" <[email protected]>

As the event-fork option requires doing work when enabled and disabled, it can not be passed down to created instances. The instance must clear this flag when it is created, and must clear it when its removed.

As more options may be created with this need, a macro ZEROED_TRACE_FLAGS is created that holds the flags that must not be inherited by the top level instance, and must be cleared on removal of instances.

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/trace.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

kernel/trace/trace.c +10 -1

index 988a35263fdd..5e3ad3481e4b 100644
@@ -253,6 +253,9 @@ unsigned long long ns2usecs(cycle_t nsec)
 #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK |			\
 	       TRACE_ITER_PRINTK_MSGONLY | TRACE_ITER_RECORD_CMD)
 
+/* trace_flags that are default zero for instances */
+#define ZEROED_TRACE_FLAGS \
+	TRACE_ITER_EVENT_FORK
 
 /*
  * The global_trace is the descriptor that holds the tracing

@@ -6710,7 +6713,7 @@ static int instance_mkdir(const char *name)
 	if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL))
 		goto out_free_tr;
 
-	tr->trace_flags = global_trace.trace_flags;
+	tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS;
 
 	cpumask_copy(tr->tracing_cpumask, cpu_all_mask);

@@ -6784,6 +6787,12 @@ static int instance_rmdir(const char *name)
 
 	list_del(&tr->list);
 
+	/* Disable all the flags that were enabled coming in */
+	for (i = 0; i < TRACE_FLAGS_MAX_SIZE; i++) {
+		if ((1 << i) & ZEROED_TRACE_FLAGS)
+			set_tracer_flag(tr, 1 << i, 0);
+	}
+
 	tracing_set_nop(tr);
 	event_trace_del_tracer(tr);
 	ftrace_destroy_function_files(tr);

Signature · 1 line

2.8.0.rc3

Steven Rostedt

author maintainer

2016-04-27 16:32 UTC #2 lore raw

PATCH 2/5 tracing: checking for NULL instead of IS_ERR()

In reply to Steven Rostedt

From: Dan Carpenter <[email protected]>

tracing_map_elt_alloc() returns ERR_PTRs on error, never NULL.

Fixes 08d43a5fa063 ('tracing: Add lock-free tracing_map')

Link http://lkml.kernel.org/r/20160423102347.GA11136@mwanda open here

Acked-by Tom Zanussi <[email protected]>

Signed-off-by Dan Carpenter <[email protected]>

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/tracing_map.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

kernel/trace/tracing_map.c +1 -1

index e0f172932eca..e7dfc5eec669 100644
@@ -814,7 +814,7 @@ static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
 	unsigned int i;
 
 	dup_elt = tracing_map_elt_alloc(elt->map);
-	if (!dup_elt)
+	if (IS_ERR(dup_elt))
 		return NULL;
 
 	if (elt->map->ops && elt->map->ops->elt_copy)

Signature · 1 line

2.8.0.rc3

Steven Rostedt

author maintainer

2016-04-27 16:32 UTC #3 lore raw

PATCH 3/5 tracing: Add check for NULL event field when creating hist field

In reply to Steven Rostedt

From: Tom Zanussi <[email protected]>

Smatch flagged create_hist_field() as possibly being able to dereference a NULL pointer, although the current code exits in all cases where the event field could be NULL, so it's not actually a problem.

Still, to prevent future changes to the code from overlooking new cases, make the NULL pointer check explicit and warn once in that case.

Link http://lkml.kernel.org/r/cfbc003f534a3e441b4313272fd412310aba6336.1461610073.git.tom.zanussi@linux.intel.com open here

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

Signed-off-by Steven Rostedt <[email protected]>

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

kernel/trace/trace_events_hist.c +3 -0

index f98b6b3a2804..0c05b8a99806 100644
@@ -371,6 +371,9 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 		goto out;
 	}
 
+	if (WARN_ON_ONCE(!field))
+		goto out;
+
 	if (is_string_field(field)) {
 		flags |= HIST_FIELD_FL_STRING;

Signature · 1 line

2.8.0.rc3

Steven Rostedt

author maintainer

2016-04-27 16:33 UTC #4 lore raw

PATCH 4/5 tracing: Handle tracing_map_alloc_elts() error path correctly

In reply to Steven Rostedt

From: Tom Zanussi <[email protected]>

If tracing_map_elt_alloc() fails, it will return ERR_PTR() instead of NULL, so change the check to IS_ERROR(). We also need to set the failed entry in the map->elts array to NULL instead of ERR_PTR() so tracing_map_free_elts() doesn't try freeing an ERR_PTR().

tracing_map_free_elts() should also zero out what it frees so a reentrant call won't find previously freed elements.

Link http://lkml.kernel.org/r/f29d03b00bce3aac8cf151a8a30e6c83e5fee66d.1461610073.git.tom.zanussi@linux.intel.com open here

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

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/tracing_map.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

kernel/trace/tracing_map.c +6 -2

index e7dfc5eec669..0a689bbb78ef 100644
@@ -366,10 +366,13 @@ static void tracing_map_free_elts(struct tracing_map *map)
 	if (!map->elts)
 		return;
 
-	for (i = 0; i < map->max_elts; i++)
+	for (i = 0; i < map->max_elts; i++) {
 		tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
+		*(TRACING_MAP_ELT(map->elts, i)) = NULL;
+	}
 
 	tracing_map_array_free(map->elts);
+	map->elts = NULL;
 }
 
 static int tracing_map_alloc_elts(struct tracing_map *map)

@@ -383,7 +386,8 @@ static int tracing_map_alloc_elts(struct tracing_map *map)
 
 	for (i = 0; i < map->max_elts; i++) {
 		*(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
-		if (!(*(TRACING_MAP_ELT(map->elts, i)))) {
+		if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
+			*(TRACING_MAP_ELT(map->elts, i)) = NULL;
 			tracing_map_free_elts(map);
 
 			return -ENOMEM;

Signature · 1 line

2.8.0.rc3

Steven Rostedt

author maintainer

2016-04-27 16:33 UTC #5 lore raw

PATCH 5/5 tracing: Dont use the address of the buffer array name in copy_from_user

In reply to Steven Rostedt

From: Wang Xiaoqiang <[email protected]>

With the following code snippet:

    ...
    char buf[64];
    ...
    if (copy_from_user(&buf, ubuf, cnt))
    ...

Even though the value of "&buf" equals "buf", but there is no need to get the address of the "buf" again. Use "buf" instead of "&buf".

Link http://lkml.kernel.org/r/20160418152329.18b72bea@debian open here

Signed-off-by Wang Xiaoqiang <[email protected]>

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/trace.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

kernel/trace/trace.c +3 -3

index 5e3ad3481e4b..46028d47d252 100644
@@ -3664,7 +3664,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 	if (cnt >= sizeof(buf))
 		return -EINVAL;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;

@@ -4537,7 +4537,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 	if (cnt > MAX_TRACER_SIZE)
 		cnt = MAX_TRACER_SIZE;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;

@@ -5327,7 +5327,7 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
 	if (cnt >= sizeof(buf))
 		return -EINVAL;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;

Signature · 1 line

2.8.0.rc3