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Message-ID: <ee461aca-40c6-4e81-baf0-60d52f7a6577@xs4all.nl>
Date: Thu, 29 Feb 2024 13:36:08 +0100
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Subject: Re: [PATCH] media: fix task hung in vb2_video_unregister_device
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To: Edward Adam Davis <eadavis@qq.com>,
 syzbot+2622b51b35f91a00ea18@syzkaller.appspotmail.com
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
 linux-usb@vger.kernel.org, m.szyprowski@samsung.com, mchehab@kernel.org,
 syzkaller-bugs@googlegroups.com, tfiga@chromium.org
References: <0000000000008faf0a06126a0ffb@google.com>
 <tencent_70C492C20645C99DEEC9EED28C8E27D40606@qq.com>
From: Hans Verkuil <hverkuil@xs4all.nl>
In-Reply-To: <tencent_70C492C20645C99DEEC9EED28C8E27D40606@qq.com>
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On 2/29/24 13:21, Edward Adam Davis wrote:
> vb2_video_unregister_device() will get vb2q_lock, so usbtv_video_free() does
> not need vb2q_lock.
> 
> Reported-and-tested-by: syzbot+2622b51b35f91a00ea18@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>

Duplicate of:

https://lore.kernel.org/linux-media/19cdefd3-163b-41a1-b603-764aab4b5b90@xs4all.nl/

I'm waiting for a v2 of that one.

Regards,

	Hans

> ---
>  drivers/media/usb/usbtv/usbtv-video.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/media/usb/usbtv/usbtv-video.c b/drivers/media/usb/usbtv/usbtv-video.c
> index 62a583040cd4..b55f432b44d4 100644
> --- a/drivers/media/usb/usbtv/usbtv-video.c
> +++ b/drivers/media/usb/usbtv/usbtv-video.c
> @@ -963,7 +963,6 @@ int usbtv_video_init(struct usbtv *usbtv)
>  
>  void usbtv_video_free(struct usbtv *usbtv)
>  {
> -	mutex_lock(&usbtv->vb2q_lock);
>  	mutex_lock(&usbtv->v4l2_lock);
>  
>  	usbtv_stop(usbtv);
> @@ -971,7 +970,6 @@ void usbtv_video_free(struct usbtv *usbtv)
>  	v4l2_device_disconnect(&usbtv->v4l2_dev);
>  
>  	mutex_unlock(&usbtv->v4l2_lock);
> -	mutex_unlock(&usbtv->vb2q_lock);
>  
>  	v4l2_device_put(&usbtv->v4l2_dev);
>  }