Re: [PATCH] ALSA: aloop: Fix &cable->lock deadlock issues

[Takashi Iwai <tiwai@suse.de>]

On Sun, 25 Jun 2023 18:22:56 +0200,
YE Chengfeng wrote:
> 
> The timer loopback_jiffies_timer_function is executed under
> bottom-half softirq context and require a spinlock, thus
> other process context code requiring the same lock (i.e.,
> loopback_trigger, loopback_pointer) can deadlock with the
> timer if it is preempted while holding the lock.
> 
> Deadlock scenario:
> loopback_trigger
>     -> spin_lock(&cable->lock);
>         <timer interrupt>
>         -> loopback_jiffies_timer_function
>         -> spin_lock_irqsave(&dpcm->cable->lock, flags);
> 
> Fix the potential deadlock by using spin_lock_irqsave.

Similarly like the patch for snd-dummy, this change looks superfluous,
too.


thanks,

Takashi