Re: [PATCH] sound: usb: get lock before calling usb_enable_autosuspend()

[Takashi Iwai]

On Tue, 03 Aug 2021 00:53:39 +0200,
Salah Triki wrote:
> 
> Based on the documentation of usb_enable_autosuspend(), the
> caller must hold udev's device lock.

The device lock is already held in the caller side (in the driver
core), hence this change will lead to a deadlock.


thanks,

Takashi

> 
> Signed-off-by: Salah Triki <salah.triki@xxxxxxxxx>
> ---
>  sound/usb/card.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index 2f6a62416c05..9290ba0acd5f 100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -907,8 +907,13 @@ static void usb_audio_disconnect(struct usb_interface *intf)
>  		}
>  	}
>  
> -	if (chip->quirk_type & QUIRK_SETUP_DISABLE_AUTOSUSPEND)
> -		usb_enable_autosuspend(interface_to_usbdev(intf));
> +	if (chip->quirk_type & QUIRK_SETUP_DISABLE_AUTOSUSPEND) {
> +		struct usb_device *udev = interface_to_usbdev(intf);
> +
> +		usb_lock_device(udev);
> +		usb_enable_autosuspend(udev);
> +		usb_unlock_device(udev);
> +	}
>  
>  	chip->num_interfaces--;
>  	if (chip->num_interfaces <= 0) {
> -- 
> 2.25.1
>