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| author | Takashi Iwai <tiwai@suse.de> | 2021-07-16 15:27:23 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2021-07-17 09:55:10 +0200 |
| commit | 1c2b9519159b470ef24b2638f4794e86e2952ab7 (patch) | |
| tree | 9733fefee4023bb0ed3910d81a0a95635c47399e /sound/isa | |
| parent | 64752a95b702817602d72f109ceaf5ec0780e283 (diff) | |
| download | lwn-1c2b9519159b470ef24b2638f4794e86e2952ab7.tar.gz lwn-1c2b9519159b470ef24b2638f4794e86e2952ab7.zip | |
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.c | 4 |
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); |