5.1-stable patches

[thirdparty/kernel/stable-queue.git] / releases / 3.0.1 / perf-fix-software-event-overflow.patch

From a.p.zijlstra@chello.nl  Tue Aug  2 09:32:36 2011
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu, 28 Jul 2011 20:47:10 +0200
Subject: perf: Fix software event overflow
To: Vince Weaver <vweaver1@eecs.utk.edu>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>, linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo <acme@ghostprotocols.net>, stable <stable@kernel.org>
Message-ID: <1311878830.2617.373.camel@laptop>

From: Peter Zijlstra <a.p.zijlstra@chello.nl>

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>

---
 kernel/events/core.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5016,11 +5016,8 @@ static int __perf_event_overflow(struct
 	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)