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 <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

0 files changed, 0 insertions, 0 deletions