Commit-ID:  524eff183f51d080a83b348d0ea97c08b3607b9a
Gitweb:     http://git.kernel.org/tip/524eff183f51d080a83b348d0ea97c08b3607b9a
Author:     Jiri Olsa <[email protected]>
AuthorDate: Mon, 6 May 2013 18:27:17 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 7 May 2013 13:17:28 +0200

perf: Fix EXIT event notification

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 <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Borislav Petkov <[email protected]>
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/events/core.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6b41c18..38b68a0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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;
 
@@ -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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