[tip:perf/core] perf: De-schedule a task context when removing the last event

[tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>]

Commit-ID:  64ce312618ef0e11d88def80effcefd1b59fdb1e
Gitweb:     http://git.kernel.org/tip/64ce312618ef0e11d88def80effcefd1b59fdb1e
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Sat, 9 Apr 2011 21:17:48 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 28 May 2011 18:01:23 +0200

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>
---
 kernel/events/core.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c378062..cc5d57d 100644
--- 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;