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