ALSA: sb: Fix potential ABBA deadlock in CSP driver

commit 1c2b9519 upstream.

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org