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ALSA: sound/isa: convert nested spin_lock_irqsave to spin_lock 

If spin_lock_irqsave is called twice in a row with the same second
argument, the interrupt state at the point of the second call overwrites
the value saved by the first call.  Indeed, the second call does not need
to save the interrupt state, so it is changed to a simple spin_lock.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression lock1,lock2;
expression flags;
@@

*spin_lock_irqsave(lock1,flags)
... when != flags
*spin_lock_irqsave(lock2,flags)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Julia Lawall 2009-07-18 17:26:14 +02:00 committed by Takashi Iwai
parent cb65c8732a
commit fcb2954b96
1 changed files with 2 additions and 2 deletions
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4
sound/isa/gus/gus_pcm.c
View File

@ -795,13 +795,13 @@ static int snd_gf1_pcm_volume_put(struct snd_kcontrol *kcontrol, struct snd_ctl_
if (!(pcmp->flags & SNDRV_GF1_PCM_PFLG_ACTIVE))
continue;
/* load real volume - better precision */
spin_lock_irqsave(&gus->reg_lock, flags);
spin_lock(&gus->reg_lock);
snd_gf1_select_voice(gus, pvoice->number);
snd_gf1_ctrl_stop(gus, SNDRV_GF1_VB_VOLUME_CONTROL);
vol = pvoice == pcmp->pvoices[0] ? gus->gf1.pcm_volume_level_left : gus->gf1.pcm_volume_level_right;
snd_gf1_write16(gus, SNDRV_GF1_VW_VOLUME, vol);
pcmp->final_volume = 1;
spin_unlock_irqrestore(&gus->reg_lock, flags);
spin_unlock(&gus->reg_lock);
}
spin_unlock_irqrestore(&gus->voice_alloc, flags);
return change;