[tip:perf/fast] perf: Fix mmap_page::offset computation

[tip:perf/fast] perf: Fix mmap_page::offset computation

[tip-bot for Peter Zijlstra]

Commit-ID:  365a4038486b57bb2bd516706a80f82f250f5306
Gitweb:     http://git.kernel.org/tip/365a4038486b57bb2bd516706a80f82f250f5306
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Mon, 21 Nov 2011 20:58:59 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 21 Dec 2011 11:01:09 +0100

perf: Fix mmap_page::offset computation

There's multiple reason the counter might be unavailable, change the
condition to !->index since perf_event_index() should return 0 for all
those cases.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-1ixr3olci40w8rgv2evv2ldh@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/events/core.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3894309..05affc3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3268,7 +3268,7 @@ void perf_event_update_userpage(struct perf_event *event)
 	barrier();
 	userpg->index = perf_event_index(event);
 	userpg->offset = perf_event_count(event);
-	if (event->state == PERF_EVENT_STATE_ACTIVE)
+	if (userpg->index)
 		userpg->offset -= local64_read(&event->hw.prev_count);
 
 	userpg->time_enabled = enabled +