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perf: Fix perf_event_comm() vs. exec() assumption

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perf_event_comm() assumes that set_task_comm() is only called on
exec(), and in particular that its only called on current.

Neither are true, as Dave reported a WARN triggered by set_task_comm()
being called on !current.

Separate the exec() hook from the comm hook.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20140521153219.GH5226@laptop.programming.kicks-ass.net
[ Build fix. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2014-06-06 07:54:02 +02:00
committed by Ingo Molnar
parent 22c91aa235
commit e041e328c4
3 changed files with 20 additions and 13 deletions
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kernel/events/core.c
+16 -12
View File
@@ -2970,6 +2970,22 @@ out:
local_irq_restore(flags);
}
void perf_event_exec(void)
{
struct perf_event_context *ctx;
int ctxn;
rcu_read_lock();
for_each_task_context_nr(ctxn) {
ctx = current->perf_event_ctxp[ctxn];
if (!ctx)
continue;
perf_event_enable_on_exec(ctx);
}
rcu_read_unlock();
}
/*
* Cross CPU call to read the hardware event
*/
@@ -5057,18 +5073,6 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
void perf_event_comm(struct task_struct *task)
{
struct perf_comm_event comm_event;
struct perf_event_context *ctx;
int ctxn;
rcu_read_lock();
for_each_task_context_nr(ctxn) {
ctx = task->perf_event_ctxp[ctxn];
if (!ctx)
continue;
perf_event_enable_on_exec(ctx);
}
rcu_read_unlock();
if (!atomic_read(&nr_comm_events))
return;