Re: [PATCH v2 2/2] ALSA: caiaq: take a reference on the USB device in create_card()

[Takashi Iwai <tiwai@suse.de>]

On Mon, 13 Apr 2026 05:49:41 +0200,
Berk Cem Goksel wrote:
> 
> The caiaq driver stores a pointer to the parent USB device in
> cdev->chip.dev but never takes a reference on it. The card's
> private_free callback, snd_usb_caiaq_card_free(), can run
> asynchronously via snd_card_free_when_closed() after the USB
> device has already been disconnected and freed, so any access to
> cdev->chip.dev in that path dereferences a freed usb_device.
> 
> On top of the refcounting issue, the current card_free implementation
> calls usb_reset_device(cdev->chip.dev). A reset in a free callback
> is inappropriate: the device is going away, the call takes the
> device lock in a teardown context, and the reset races with the
> disconnect path that the callback is already cleaning up after.
> 
> Take a reference on the USB device in create_card() with
> usb_get_dev(), drop it with usb_put_dev() in the free callback,
> and remove the usb_reset_device() call.
> 
> Fixes: b04dcbb7f7b1 ("ALSA: caiaq: Use snd_card_free_when_closed() at disconnection")
> Cc: stable@vger.kernel.org
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Signed-off-by: Berk Cem Goksel <berkcgoksel@gmail.com>
> ---
> v2:
>  - Correct "Fixes:" tag
>  - Remove null check before the usb_put_dev() call in card_free()

Applied now.  Thanks.


Takashi