perf: Fix perf_event_comm() vs. exec() assumption
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>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 440eefc..647698f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2970,6 +2970,22 @@
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 @@
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;