perf: De-schedule a task context when removing the last event

Since perf_install_in_context() will now install a context when we
add the first event, we can de-schedule the context when the last
event is removed.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192142.090431763@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c378062..cc5d57d 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1120,6 +1120,10 @@ static int __perf_remove_from_context(void *info)
        raw_spin_lock(&ctx->lock);
        event_sched_out(event, cpuctx, ctx);
        list_del_event(event, ctx);
+       if (!ctx->nr_events && cpuctx->task_ctx == ctx) {
+               ctx->is_active = 0;
+               cpuctx->task_ctx = NULL;
+       }
        raw_spin_unlock(&ctx->lock);
 
        return 0;