[PATCH] [ALSA] soc - fsl_ssi.c fix "BUG: scheduling while atomic"

[PATCH] [ALSA] soc - fsl_ssi.c fix "BUG: scheduling while atomic"

[Anton Vorontsov]

This patch fixes following bug caught with PREEMPT enabled:

root@b1:~# cat /dev/dsp > /dev/null
BUG: scheduling while atomic: cat/965/0x00000003
Call Trace:
[df165ce0] [c0008e84] show_stack+0x4c/0x1ac (unreliable)
[df165d20] [c001c18c] __schedule_bug+0x64/0x78
[df165d30] [c02b3344] schedule+0x2d8/0x334
[df165d70] [c02b3674] schedule_timeout+0x64/0xe4
[df165db0] [c002c05c] msleep+0x1c/0x34
[df165dc0] [c01f2fe0] fsl_ssi_trigger+0x130/0x144
[df165dd0] [c01ece54] soc_pcm_trigger+0x94/0xb8
[df165df0] [c01da764] snd_pcm_do_start+0x48/0x60
[df165e00] [c01da630] snd_pcm_action_single+0x4c/0xb4
[df165e20] [c01e0f50] snd_pcm_lib_read1+0x2a0/0x2d4
[df165e70] [c01ec274] snd_pcm_oss_read3+0xf0/0x13c
[df165eb0] [c01ec2e4] snd_pcm_oss_read2+0x24/0x4c
[df165ec0] [c01ec4ac] snd_pcm_oss_read+0x1a0/0x1f0
[df165ef0] [c0076478] vfs_read+0xb4/0x108
[df165f10] [c00768cc] sys_read+0x4c/0x90
[df165f40] [c00117a4] ret_from_syscall+0x0/0x38
--- Exception: c01 at 0xfe9a8d4
    LR = 0x10002b24

We must not sleep with irqs disabled, so replace msleep with mdelay.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
---
 sound/soc/fsl/fsl_ssi.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
index b2a11b0..f588545 100644
--- a/sound/soc/fsl/fsl_ssi.c
+++ b/sound/soc/fsl/fsl_ssi.c
@@ -416,7 +416,7 @@ static int fsl_ssi_trigger(struct snd_pcm_substream *substream, int cmd)
 			 * to put data into its FIFO.  Without it, ALSA starts
 			 * to complain about overruns.
 			 */
-			msleep(1);
+			mdelay(1);
 		}
 		break;
 
-- 
1.5.5.1

Re: [PATCH] [ALSA] soc - fsl_ssi.c fix "BUG: scheduling while atomic"

[Timur Tabi]

Anton Vorontsov wrote:

> We must not sleep with irqs disabled, so replace msleep with mdelay.
> 
> Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>

Acked-By: Timur Tabi <timur@freescale.com>

Anton, can you try testing the code with the call to mdelay/msleep commented
out?  On my quick test, I didn't need it, so I have a suspicion that it was
needed only for the old 1.0 silicon.

-- 
Timur Tabi
Linux kernel developer at Freescale

Re: [PATCH] [ALSA] soc - fsl_ssi.c fix "BUG: scheduling while atomic"

[Anton Vorontsov]

On Thu, May 08, 2008 at 02:19:36PM -0500, Timur Tabi wrote:
> Anton Vorontsov wrote:
> 
> > We must not sleep with irqs disabled, so replace msleep with mdelay.
> > 
> > Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
> 
> Acked-By: Timur Tabi <timur@freescale.com>
> 
> Anton, can you try testing the code with the call to mdelay/msleep commented
> out?

Ok, I'll try...

> On my quick test, I didn't need it, so I have a suspicion that it was
> needed only for the old 1.0 silicon.

Are there any drawbacks of mdelay'ing? Since some silicons need this
we'd better leave it then.

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2

Re: [PATCH] [ALSA] soc - fsl_ssi.c fix "BUG: scheduling while atomic"

[Timur Tabi]

Anton Vorontsov wrote:

> Are there any drawbacks of mdelay'ing? 

All I remember is that without the delay, it wouldn't work.  But that was a long
time ago, and I never revisited the issue, even after the silicon was updated.

> Since some silicons need this
> we'd better leave it then.

The 1.0 silicon is dead and won't work with this driver anyway.  We should still
leave it in for now, but I plan on doing thorough testing without it.  If the
driver still works, I'll remove it for ASoC V2.

-- 
Timur Tabi
Linux kernel developer at Freescale