From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu, 28 Jul 2011 18:47:10 +0000 (+0200)
Subject: perf: Fix software event overflow
X-Git-Tag: v3.0.1~63
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=462fee3af72df0de7b60b96c525ffe8baf4db0f0;p=karo-tx-linux.git

perf: Fix software event overflow

The below patch is for -stable only, upstream has a much larger patch
that contains the below hunk in commit a8b0ca17b80e92faab46ee7179ba9e99ccb61233

Vince found that under certain circumstances software event overflows
go wrong and deadlock. Avoid trying to delete a timer from the timer
callback.

Reported-by: Vince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9efe7108ccaf..32a61513f890 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5016,11 +5016,8 @@ static int __perf_event_overflow(struct perf_event *event, int nmi,
 	if (events && atomic_dec_and_test(&event->event_limit)) {
 		ret = 1;
 		event->pending_kill = POLL_HUP;
-		if (nmi) {
-			event->pending_disable = 1;
-			irq_work_queue(&event->pending);
-		} else
-			perf_event_disable(event);
+		event->pending_disable = 1;
+		irq_work_queue(&event->pending);
 	}
 
 	if (event->overflow_handler)