We should disable irqs when we take the tu->qlock because it is used in the irq handler. The only place that doesn't is snd_timer_user_ccallback(). Most of the time snd_timer_user_ccallback() is called with interrupts disabled but the the first ti->ccallback() call in snd_timer_notify1() has interrupts enabled.
This was caught by lockdep which generates the following message:
================================= [ INFO: inconsistent lock state ] 2.6.34-rc5 #5
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. dolphin/4003 [HC1[1]:SC0[0]:HE0:SE1] takes: (&(&tu->qlock)->rlock){?.+...}, at: [<f84ec472>] snd_timer_user_tinterrupt+0x28/0x132 [snd_timer] {HARDIRQ-ON-W} state was registered at: [<c1048de9>] __lock_acquire+0x654/0x1482 [<c1049c73>] lock_acquire+0x5c/0x73 [<c125ac3e>] _raw_spin_lock+0x25/0x34 [<f84ec370>] snd_timer_user_ccallback+0x55/0x95 [snd_timer] [<f84ecc4b>] snd_timer_notify1+0x53/0xca [snd_timer]
Reported-by: Stefan Richter stefanr@s5r6.in-berlin.de Signed-off-by: Dan Carpenter error27@gmail.com
diff --git a/sound/core/timer.c b/sound/core/timer.c index 7394365..5040c7b 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -1160,6 +1160,7 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, { struct snd_timer_user *tu = timeri->callback_data; struct snd_timer_tread r1; + unsigned long flags;
if (event >= SNDRV_TIMER_EVENT_START && event <= SNDRV_TIMER_EVENT_PAUSE) @@ -1169,9 +1170,9 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, r1.event = event; r1.tstamp = *tstamp; r1.val = resolution; - spin_lock(&tu->qlock); + spin_lock_irqsave(&tu->qlock, flags); snd_timer_user_append_to_tqueue(tu, &r1); - spin_unlock(&tu->qlock); + spin_unlock_irqrestore(&tu->qlock, flags); kill_fasync(&tu->fasync, SIGIO, POLL_IN); wake_up(&tu->qchange_sleep); }