Re: [PATCH] ALSA: info: Fix potential deadlock at disconnection

[Jaroslav Kysela <perex@xxxxxxxx>]

On 09. 11. 23 15:19, Takashi Iwai wrote:
> As reported recently, ALSA core info helper may cause a deadlock at
> the forced device disconnection during the procfs operation.
>
> The proc_remove() (that is called from the snd_card_disconnect()
> helper) has a synchronization of the pending procfs accesses via
> wait_for_completion().  Meanwhile, ALSA procfs helper takes the global
> mutex_lock(&info_mutex) at both the proc_open callback and
> snd_card_info_disconnect() helper.  Since the proc_open can't finish
> due to the mutex lock, wait_for_completion() never returns, either,
> hence it deadlocks.

Really nice fix. Thanks Takashi.

Reviewed-by: Jaroslav Kysela <perex@xxxxxxxx>

(maybe Cc: to stable?)

					Jaroslav

--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.