Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35;
Date:   Wed, 22 Nov 2023 17:01:32 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Ricardo Ribalda <ribalda@chromium.org>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Tomasz Figa <tfiga@chromium.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Sean Paul <seanpaul@chromium.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: Re: [PATCH v3 2/3] media: uvcvideo: Do not halt the device after
 disconnect
Message-ID: <20231122080132.GA1526356@google.com>
References: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org>
 <20231121-guenter-mini-v3-2-d8a5eae2312b@chromium.org>
 <20231122074742.GB1465745@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20231122074742.GB1465745@google.com>
Precedence: bulk

On (23/11/22 16:47), Sergey Senozhatsky wrote:
> Can the following happen?

Consider the following case (when CPU1 experienced a delay, a preemption
or anything):

> CPU0                                            CPU1
>  uvc_disconnect()
> 						uvc_video_stop_streaming()
>  usb_set_intfdata()
>  uvc_unregister_video()
> 
> 						if (!smp_load(&dev->disconnected))
> 
>  smp_store_release(&dev->disconnected, true);
> 
>  kref_put(&dev->ref, uvc_delete);

> 							uvc_video_halt()

That uvc_video_halt() cannot be legal, right?