On Tue, 27 Jun 2023 11:56:16 +0200, Chengfeng Ye wrote: > > As &chip->mixer_lock is also acquired by the irq snd_sb8dsp_interrupt() > which executes under hard-irq context, code executing under process > context should disable irq before acquiring the lock, otherwise > deadlock could happen if the process context hold the lock then > preempt by the interruption. > > As the ALSA Driver document described, PCM prepare callbacks are not > executed with irq disabled by default, thus the acquiring of > &chip->mixer_lock should be irq disabled. > > Possible deadlock scenario: > snd_sb8_playback_prepare > -> spin_lock(&chip->mixer_lock); > <irq interrupt> > -> snd_sb8dsp_interrupt() > -> snd_sb8_capture_trigger() > -> spin_lock(&chip->mixer_lock); (deadlock here) > > This flaw was found using an experimental static analysis tool we are > developing for irq-related deadlock. > > The tentative patch fix the potential deadlock by spin_lock_irqsave(). > > Signed-off-by: Chengfeng Ye <dg573847474@xxxxxxxxx> I believe it's a false-positive. There is already a call spin_lock_irqsave(&chip->reg_lock, flags); beforehand. thanks, Takashi
