linux-kernel - [PATCH 3.12 66/78] ALSA: timer: Sync timer deletion at closing the system timer

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Date:	Fri, 22 Apr 2016 13:05:49 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 66/78] ALSA: timer: Sync timer deletion at closing the system timer

From: Takashi Iwai <tiwai@...e.de>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit f146357f069e71aff8e474c625bcebcd3094b3ab upstream.

ALSA timer core framework has no sync point at stopping because it's
called inside the spinlock.  Thus we need a sync point at close for
avoiding the stray timer task.  This is simply done by implementing
the close callback just calling del_timer_sync().  (It's harmless to
call it unconditionally, as the core timer itself cares of the already
deleted timer instance.)

Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 sound/core/timer.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 38742e826900..10463beae4bb 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -1033,11 +1033,21 @@ static int snd_timer_s_stop(struct snd_timer * timer)
 	return 0;
 }
 
+static int snd_timer_s_close(struct snd_timer *timer)
+{
+	struct snd_timer_system_private *priv;
+
+	priv = (struct snd_timer_system_private *)timer->private_data;
+	del_timer_sync(&priv->tlist);
+	return 0;
+}
+
 static struct snd_timer_hardware snd_timer_system =
 {
 	.flags =	SNDRV_TIMER_HW_FIRST | SNDRV_TIMER_HW_TASKLET,
 	.resolution =	1000000000L / HZ,
 	.ticks =	10000000L,
+	.close =	snd_timer_s_close,
 	.start =	snd_timer_s_start,
 	.stop =		snd_timer_s_stop
 };
-- 
2.8.1