The perf_event_task_ctx 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]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Corey Ashford <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Borislav Petkov <[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(); } -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
