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authorTakashi Iwai <tiwai@suse.de>2021-07-16 15:27:23 +0200
committerTakashi Iwai <tiwai@suse.de>2021-07-17 09:55:10 +0200
commit1c2b9519159b470ef24b2638f4794e86e2952ab7 (patch)
tree9733fefee4023bb0ed3910d81a0a95635c47399e /sound/isa
parent64752a95b702817602d72f109ceaf5ec0780e283 (diff)
ALSA: sb: Fix potential ABBA deadlock in CSP driver
SB16 CSP driver may hit potentially a typical ABBA deadlock in two code paths: In snd_sb_csp_stop(): spin_lock_irqsave(&p->chip->mixer_lock, flags); spin_lock(&p->chip->reg_lock); In snd_sb_csp_load(): spin_lock_irqsave(&p->chip->reg_lock, flags); spin_lock(&p->chip->mixer_lock); Also the similar pattern is seen in snd_sb_csp_start(). Although the practical impact is very small (those states aren't triggered in the same running state and this happens only on a real hardware, decades old ISA sound boards -- which must be very difficult to find nowadays), it's a real scenario and has to be fixed. This patch addresses those deadlocks by splitting the locks in snd_sb_csp_start() and snd_sb_csp_stop() for avoiding the nested locks. Reported-by: Jia-Ju Bai <baijiaju1990@gmail.com> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/7b0fcdaf-cd4f-4728-2eae-48c151a92e10@gmail.com Link: https://lore.kernel.org/r/20210716132723.13216-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/isa')
-rw-r--r--sound/isa/sb/sb16_csp.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/isa/sb/sb16_csp.c b/sound/isa/sb/sb16_csp.c
index 5bbe6695689d..7ad8c5f7b664 100644
--- a/sound/isa/sb/sb16_csp.c
+++ b/sound/isa/sb/sb16_csp.c
@@ -816,6 +816,7 @@ static int snd_sb_csp_start(struct snd_sb_csp * p, int sample_width, int channel
mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7);
+ spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
spin_lock(&p->chip->reg_lock);
set_mode_register(p->chip, 0xc0); /* c0 = STOP */
@@ -855,6 +856,7 @@ static int snd_sb_csp_start(struct snd_sb_csp * p, int sample_width, int channel
spin_unlock(&p->chip->reg_lock);
/* restore PCM volume */
+ spin_lock_irqsave(&p->chip->mixer_lock, flags);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR);
spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
@@ -880,6 +882,7 @@ static int snd_sb_csp_stop(struct snd_sb_csp * p)
mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7);
+ spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
spin_lock(&p->chip->reg_lock);
if (p->running & SNDRV_SB_CSP_ST_QSOUND) {
@@ -894,6 +897,7 @@ static int snd_sb_csp_stop(struct snd_sb_csp * p)
spin_unlock(&p->chip->reg_lock);
/* restore PCM volume */
+ spin_lock_irqsave(&p->chip->mixer_lock, flags);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL);
snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR);
spin_unlock_irqrestore(&p->chip->mixer_lock, flags);