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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-03-31 12:29:26 +0400
committerIngo Molnar <mingo@elte.hu>2011-03-31 15:02:55 +0400
commitab711fe08297de1485fff0a366e6db8828cafd6a (patch)
treee8a823c44d8b6bf132556f9d8aa09ec4a506c299
parent800cd25c12981c99e5401c3551ffffd99f1c6c85 (diff)
downloadlinux-ab711fe08297de1485fff0a366e6db8828cafd6a.tar.xz
perf: Fix task context scheduling
Jiri reported: | | - once an event is created by sys_perf_event_open, task context | is created and it stays even if the event is closed, until the | task is finished ... thats what I see in code and I assume it's | correct | | - when the task opens event, perf_sched_events jump label is | incremented and following callbacks are started from scheduler | | __perf_event_task_sched_in | __perf_event_task_sched_out | | These callback *in/out set/unset cpuctx->task_ctx value to the | task context. | | - close is called on event on CPU 0: | - the task is scheduled on CPU 0 | - __perf_event_task_sched_in is called | - cpuctx->task_ctx is set | - perf_sched_events jump label is decremented and == 0 | - __perf_event_task_sched_out is not called | - cpuctx->task_ctx on CPU 0 stays set | | - exit is called on CPU 1: | - the task is scheduled on CPU 1 | - perf_event_exit_task is called | - task_ctx_sched_out unsets cpuctx->task_ctx on CPU 1 | - put_ctx destroys the context | | - another call of perf_rotate_context on CPU 0 will use invalid | task_ctx pointer, and eventualy panic. | Cure this the simplest possibly way by partially reverting the jump_label optimization for the sched_out case. Reported-and-tested-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Oleg Nesterov <oleg@redhat.com> Cc: <stable@kernel.org> # .37+ LKML-Reference: <1301520405.4859.213.camel@twins> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/perf_event.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 311b4dc785a1..04d75a8a20ee 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1086,7 +1086,7 @@ void perf_event_task_sched_out(struct task_struct *task, struct task_struct *nex
{
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
- COND_STMT(&perf_sched_events, __perf_event_task_sched_out(task, next));
+ __perf_event_task_sched_out(task, next);
}
extern void perf_event_mmap(struct vm_area_struct *vma);