diff options
| author | Takashi Iwai <tiwai@suse.de> | 2016-04-01 12:28:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-20 15:41:53 +0900 |
| commit | 57f21bd260958fbfda2ef819a7fa8a0054df0c68 (patch) | |
| tree | 77ed1ab43c459a57d28fcfc1ae268c6c3d293541 /sound | |
| parent | 4d6deebe06c5383dffe9cba859378ca708d4076d (diff) | |
ALSA: timer: Use mod_timer() for rearming the system timer
commit 4a07083ed613644c96c34a7dd2853dc5d7c70902 upstream.
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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/timer.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c index f24c9fccf008..b982d1b089bd 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; } |