Hello,
I find there is a possible ABBA deadlock in the SB16 driver in Linux 5.10:
In snd_sb_csp_stop():
876: spin_lock_irqsave(&p->chip->mixer_lock, flags);
882: spin_lock(&p->chip->reg_lock);
In snd_sb_csp_load():
614: spin_lock_irqsave(&p->chip->reg_lock, flags);
653: spin_lock(&p->chip->mixer_lock);
When snd_sb_csp_stop() and snd_sb_csp_load() are concurrently executed,
the deadlock can occur.
I check the code and find a possible case of such concurrent execution:
#CPU1:
snd_sb16_playback_close
snd_sb16_csp_playback_close (csp->ops.csp_stop(csp))
snd_sb_csp_stop
#CPU2:
snd_sb_csp_ioctl
snd_sb_csp_riff_load
snd_sb_csp_load_user
snd_sb_csp_load
I am not quite sure whether this possible deadlock is real and how to
fix it if it is real.
Any feedback would be appreciated, thanks
Best wishes,
Jia-Ju Bai
