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perf: Fix EXIT event notification
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The perf_event_task_ctx() function needs to be called with
preemption disabled, since it's checking for currently
scheduled cpu against event cpu.

We disable preemption for task related perf event context
if there's one defined, leaving up to the chance which cpu
it gets scheduled in.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1367857638-27631-2-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Jiri Olsa authored and Ingo Molnar committed May 7, 2013
1 parent 534c97b commit 524eff1
Showing 1 changed file with 14 additions and 12 deletions.
26 changes: 14 additions & 12 deletions kernel/events/core.c
Original file line number Diff line number Diff line change
Expand Up @@ -4474,7 +4474,7 @@ static void perf_event_task_ctx(struct perf_event_context *ctx,
static void perf_event_task_event(struct perf_task_event *task_event)
{
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
struct perf_event_context *ctx, *task_ctx = task_event->task_ctx;
struct pmu *pmu;
int ctxn;

Expand All @@ -4485,20 +4485,22 @@ static void perf_event_task_event(struct perf_task_event *task_event)
goto next;
perf_event_task_ctx(&cpuctx->ctx, task_event);

ctx = task_event->task_ctx;
if (!ctx) {
ctxn = pmu->task_ctx_nr;
if (ctxn < 0)
goto next;
ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
if (ctx)
perf_event_task_ctx(ctx, task_event);
}
if (task_ctx)
goto next;
ctxn = pmu->task_ctx_nr;
if (ctxn < 0)
goto next;
ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
if (ctx)
perf_event_task_ctx(ctx, task_event);
next:
put_cpu_ptr(pmu->pmu_cpu_context);
}
if (task_event->task_ctx)
perf_event_task_ctx(task_event->task_ctx, task_event);
if (task_ctx) {
preempt_disable();
perf_event_task_ctx(task_ctx, task_event);
preempt_enable();
}

rcu_read_unlock();
}
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