linux-kernel - Re: [-mm patch] pcm_native: lockdep warning when launching jack

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Date:	Thu, 05 Apr 2007 17:00:41 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Frederik Deweerdt <deweerdt@...e.fr>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, perex@...e.cz
Subject: Re: [-mm patch] pcm_native: lockdep warning when launching jack

At Thu, 5 Apr 2007 15:53:50 +0200,
Frederik Deweerdt wrote:
> 
> On Mon, Apr 02, 2007 at 10:47:45PM -0700, Andrew Morton wrote:
> > 
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21-rc5/2.6.21-rc5-mm4/
> > 
> Hi,
> 
> When launching "jackd -d alsa", lockdep issues the following warning:
> [39701.405086] =============================================
> [39701.405093] [ INFO: possible recursive locking detected ]
> [39701.405107] 2.6.21-rc5-mm4 #2
> [39701.405109] ---------------------------------------------
> [39701.405112] jackd/17366 is trying to acquire lock:
> [39701.405114]  (&substream->self_group.lock){....}, at: [<c034d3c0>] snd_pcm_action_group+0x90/0x240
> [39701.405131]
> [39701.405131] but task is already holding lock:
> [39701.405134]  (&substream->self_group.lock){....}, at: [<c034d63f>] snd_pcm_action_lock_irq+0x3f/0xb0
> [39701.405141]
> [39701.405142] other info that might help us debug this:
> [39701.405145] 3 locks held by jackd/17366:
> [39701.405147]  #0:  (snd_pcm_link_rwlock){....}, at: [<c034d627>] snd_pcm_action_lock_irq+0x27/0xb0
> [39701.405155]  #1:  (&substream->group->lock){....}, at: [<c034d638>] snd_pcm_action_lock_irq+0x38/0xb0
> [39701.405163]  #2:  (&substream->self_group.lock){....}, at: [<c034d63f>] snd_pcm_action_lock_irq+0x3f/0xb0
> [39701.405171]
> [39701.405171] stack backtrace:
> [39701.405174]  [<c0103b8a>] show_trace_log_lvl+0x1a/0x30
> [39701.405179]  [<c0104912>] show_trace+0x12/0x20
> [39701.405183]  [<c01049c6>] dump_stack+0x16/0x20
> [39701.405187]  [<c013b980>] __lock_acquire+0xbd0/0x1040
> [39701.405193]  [<c013be60>] lock_acquire+0x70/0x90
> [39701.405197]  [<c0407846>] _spin_lock+0x36/0x50
> [39701.405203]  [<c034d3c0>] snd_pcm_action_group+0x90/0x240
> [39701.405207]  [<c034d653>] snd_pcm_action_lock_irq+0x53/0xb0
> [39701.405211]  [<c035046f>] snd_pcm_common_ioctl1+0x35f/0xfb0
> [39701.405215]  [<c0351544>] snd_pcm_playback_ioctl1+0x34/0x420
> [39701.405219]  [<c03519f3>] snd_pcm_playback_ioctl+0x43/0x50
> [39701.405223]  [<c017ecc8>] do_ioctl+0x28/0x80
> [39701.405229]  [<c017ed77>] vfs_ioctl+0x57/0x290
> [39701.405233]  [<c017efe9>] sys_ioctl+0x39/0x60
> [39701.405237]  [<c0102bf4>] sysenter_past_esp+0x5d/0x99
> [39701.405240]  =======================
> 
> The attached lockdep annotation silences the warning.
> Regards,
> Frederik
> 
> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@...il.com>

Thanks, applied to ALSA tree now.

(I did a similar fix ago but forgot to merge to the upstream...)


Takashi

> 
> --- 2.6.21-rc5-mm3/sound/core/pcm_native.c	2007-03-30 21:41:18.000000000 +0200
> +++ 2.6.21-rc5-mm4/sound/core/pcm_native.c	2007-04-05 15:01:19.000000000 +0200
> @@ -718,7 +718,8 @@ static int snd_pcm_action_group(struct a
>  
>  	snd_pcm_group_for_each_entry(s, substream) {
>  		if (do_lock && s != substream)
> -			spin_lock(&s->self_group.lock);
> +			spin_lock_nested(&s->self_group.lock,
> +					 SINGLE_DEPTH_NESTING);
>  		res = ops->pre_action(s, state);
>  		if (res < 0)
>  			goto _unlock;
> 
-
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