Patch "tracing: Do not have 'comm' filter override event 'comm' field" has been added to the 4.4-stable tree
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This is a note to let you know that I've just added the patch titled
tracing: Do not have 'comm' filter override event 'comm' field
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-do-not-have-comm-filter-override-event-comm-field.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
e57cbaf0eb006eaa207395f3bfd7ce52c1b5539cMon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <[email protected]>
Date: Thu, 3 Mar 2016 17:18:20 -0500
Subject: tracing: Do not have 'comm' filter override event 'comm' field
From: Steven Rostedt (Red Hat) <[email protected]>
commit e57cbaf0eb006eaa207395f3bfd7ce52c1b5539c upstream.
Commit 9f61668073a8d "tracing: Allow triggers to filter for CPU ids and process names" added a 'comm' filter that will filter events based on the current tasks struct 'comm'. But this now hides the ability to filter events that have a 'comm' field too. For example, sched_migrate_task trace event. That has a 'comm' field of the task to be migrated.
echo 'comm == "bash"' > events/sched_migrate_task/filter
will now filter all sched_migrate_task events for tasks named "bash" that migrates other tasks (in interrupt context), instead of seeing when "bash" itself gets migrated.
This fix requires a couple of changes.
1) Change the look up order for filter predicates to look at the events fields before looking at the generic filters.
2) Instead of basing the filter function off of the "comm" name, have the generic "comm" filter have its own filter_type (FILTER_COMM). Test against the type instead of the name to assign the filter function.
3) Add a new "COMM" filter that works just like "comm" but will filter based on the current task, even if the trace event contains a "comm" field.
Do the same for "cpu" field, adding a FILTER_CPU and a filter "CPU".
include/linux/trace_events.h +2 -0
@@ -568,6 +568,8 @@ enum {FILTER_DYN_STRING ,FILTER_PTR_STRING ,FILTER_TRACE_FN , +FILTER_COMM , + FILTER_CPU, };extern int trace_event_raw_init (struct trace_event_call *call);
kernel/trace/trace_events.c +8 -6
@@ -97,16 +97,16 @@ trace_find_event_field(struct trace_event_call *call, char *name)struct ftrace_event_field *field;struct list_head *head; - field =__find_event_field (&ftrace_generic_fields, name); + head =trace_get_fields (call); + field =__find_event_field (head, name);if (field)return field; - field =__find_event_field (&ftrace_common_fields, name); + field =__find_event_field (&ftrace_generic_fields, name);if (field)return field; - head =trace_get_fields (call); -return __find_event_field (head, name); +return __find_event_field (&ftrace_common_fields, name); } static int __trace_define_field(struct list_head *head, const char *type,
@@ -171,8 +171,10 @@ static int trace_define_generic_fields(void) {int ret; -__generic_field (int, cpu,FILTER_OTHER ); - __generic_field(char *, comm, FILTER_PTR_STRING); +__generic_field (int,CPU ,FILTER_CPU ); +__generic_field (int, cpu,FILTER_CPU ); + __generic_field(char *, COMM, FILTER_COMM); + __generic_field(char *, comm, FILTER_COMM);return ret; }
kernel/trace/trace_events_filter.c +7 -6
@@ -1043,13 +1043,14 @@ static int init_pred(struct filter_parse_state *ps,return -EINVAL ; } -if (is_string_field (field)) { +if (field->filter_type ==FILTER_COMM ) { +filter_build_regex (pred); + fn = filter_pred_comm; + pred->regex.field_len =TASK_COMM_LEN ; + }else if (is_string_field (field)) {filter_build_regex (pred); -if (!strcmp (field->name,"comm" )) { - fn = filter_pred_comm; - pred->regex.field_len =TASK_COMM_LEN ; - }else if (field->filter_type ==FILTER_STATIC_STRING ) { +if (field->filter_type ==FILTER_STATIC_STRING ) { fn = filter_pred_string; pred->regex.field_len = field->size; }else if (field->filter_type ==FILTER_DYN_STRING )
@@ -1072,7 +1073,7 @@ static int init_pred(struct filter_parse_state *ps, } pred->val = val; -if (!strcmp (field->name,"cpu" )) +if (field->filter_type ==FILTER_CPU ) fn = filter_pred_cpu;else fn = select_comparison_fn(pred->op, field->size,
Patches currently in stable-queue which might be from [email protected] are
queue-4.4/tracing-do-not-have-comm-filter-override-event-comm-field.patch