Messages in this thread Patch in this message | | | Date | Thu, 17 Mar 2011 18:15:09 +0100 | From | Takashi Iwai <> | Subject | Re: [BUG][2.6.38] IRQ Lock Inversion / i915 fails |
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At Thu, 17 Mar 2011 09:55:47 -0700, Linus Torvalds wrote: > > On Thu, Mar 17, 2011 at 2:40 AM, Knut Petersen > <Knut_Petersen@t-online.de> wrote: > > > > Well, I updated my test partition to opensuse 11.4. > > > > The opensuse standard kernel is unusable for me, booting hangs > > most of the time, the same is true for shutdown. If booting succeeds the > > system will fail after a short time of usage. > > > > So I installed kernel 2.6.38. That helped a lot ... for a few minutes. > > > > A possible irq lock inversion is detected during boot, after a short time > > X fails, restarting the X server does not work, a reboot is necessary. > > Ok, so the lock inversion seems to be due to the sound/drivers/aloop.c > file, where the function "loopback_pos_update()" gets called from > within a softirq context. And it takes a lock (cable->lock) that is > also taken unprotected by loopback_trigger(). So that's liable to > deadlock as per lockdep. Jaroslav? Takashi?
The trigger callback should be called always in irq-disabled context, so this should be OK. But loopback_pos_update() is called in the timer callback, and this can be the issue.
Knut, how about the patch below?
thanks,
Takashi
--- diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c index 12b44b0..a0da775 100644 --- a/sound/drivers/aloop.c +++ b/sound/drivers/aloop.c @@ -482,8 +482,9 @@ static unsigned int loopback_pos_update(struct loopback_cable *cable) cable->streams[SNDRV_PCM_STREAM_CAPTURE]; unsigned long delta_play = 0, delta_capt = 0; unsigned int running; + unsigned long flags; - spin_lock(&cable->lock); + spin_lock_irqsave(&cable->lock, flags); running = cable->running ^ cable->pause; if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) { delta_play = jiffies - dpcm_play->last_jiffies; @@ -495,10 +496,8 @@ static unsigned int loopback_pos_update(struct loopback_cable *cable) dpcm_capt->last_jiffies += delta_capt; } - if (delta_play == 0 && delta_capt == 0) { - spin_unlock(&cable->lock); - return running; - } + if (delta_play == 0 && delta_capt == 0) + goto unlock; if (delta_play > delta_capt) { loopback_bytepos_update(dpcm_play, delta_play - delta_capt, @@ -510,14 +509,14 @@ static unsigned int loopback_pos_update(struct loopback_cable *cable) delta_capt = delta_play; } - if (delta_play == 0 && delta_capt == 0) { - spin_unlock(&cable->lock); - return running; - } + if (delta_play == 0 && delta_capt == 0) + goto unlock; + /* note delta_capt == delta_play at this moment */ loopback_bytepos_update(dpcm_capt, delta_capt, BYTEPOS_UPDATE_COPY); loopback_bytepos_update(dpcm_play, delta_play, BYTEPOS_UPDATE_POSONLY); - spin_unlock(&cable->lock); + unlock: + spin_unlock_irqrestore(&cable->lock, flags); return running; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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