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authorTakashi Iwai <tiwai@suse.de>2016-04-01 12:28:16 +0200
committerSasha Levin <sasha.levin@oracle.com>2016-07-10 23:06:57 -0400
commitb9f2aab60bfe7f85dc9ffaeb6f258bfcd4d5bc1a (patch)
tree73c27d3cbafe07ae05dda5ef522e2ab3c9f2318d /sound
parentfb7a806fe08816a6fd2eb258db5e28218624bd07 (diff)
ALSA: timer: Use mod_timer() for rearming the system timer
[ Upstream commit 4a07083ed613644c96c34a7dd2853dc5d7c70902 ] ALSA system timer backend stops the timer via del_timer() without sync and leaves del_timer_sync() at the close instead. This is because of the restriction by the design of ALSA timer: namely, the stop callback may be called from the timer handler, and calling the sync shall lead to a hangup. However, this also triggers a kernel BUG() when the timer is rearmed immediately after stopping without sync: kernel BUG at kernel/time/timer.c:966! Call Trace: <IRQ> [<ffffffff8239c94e>] snd_timer_s_start+0x13e/0x1a0 [<ffffffff8239e1f4>] snd_timer_interrupt+0x504/0xec0 [<ffffffff8122fca0>] ? debug_check_no_locks_freed+0x290/0x290 [<ffffffff8239ec64>] snd_timer_s_function+0xb4/0x120 [<ffffffff81296b72>] call_timer_fn+0x162/0x520 [<ffffffff81296add>] ? call_timer_fn+0xcd/0x520 [<ffffffff8239ebb0>] ? snd_timer_interrupt+0xec0/0xec0 .... It's the place where add_timer() checks the pending timer. It's clear that this may happen after the immediate restart without sync in our cases. So, the workaround here is just to use mod_timer() instead of add_timer(). This looks like a band-aid fix, but it's a right move, as snd_timer_interrupt() takes care of the continuous rearm of timer. Reported-by: Jiri Slaby <jslaby@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/timer.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c
index bf48e71f73cd..1782555fcaca 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -1051,8 +1051,8 @@ static int snd_timer_s_start(struct snd_timer * timer)
njiff += timer->sticks - priv->correction;
priv->correction = 0;
}
- priv->last_expires = priv->tlist.expires = njiff;
- add_timer(&priv->tlist);
+ priv->last_expires = njiff;
+ mod_timer(&priv->tlist, njiff);
return 0;
}