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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-03-31 08:29:26 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2011-03-31 11:02:55 (GMT) |
commit | ab711fe08297de1485fff0a366e6db8828cafd6a (patch) | |
tree | e8a823c44d8b6bf132556f9d8aa09ec4a506c299 /include/linux/perf_event.h | |
parent | 800cd25c12981c99e5401c3551ffffd99f1c6c85 (diff) | |
download | linux-fsl-qoriq-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>
Diffstat (limited to 'include/linux/perf_event.h')
-rw-r--r-- | include/linux/perf_event.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 311b4dc..04d75a8 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); |