From: Hans Verkuil <hverkuil@xs4all.nl>
To: Dongliang Mu <dzm91@hust.edu.cn>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Dongliang Mu <mudongliangabcd@gmail.com>
Cc: syzkaller <syzkaller@googlegroups.com>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] media: hdpvr: call flush_work only if initialized
Date: Thu, 17 Feb 2022 13:05:42 +0100 [thread overview]
Message-ID: <b452f7a7-99fa-e023-9120-639b4110de73@xs4all.nl> (raw)
In-Reply-To: <20220217043950.749343-1-dzm91@hust.edu.cn>
On 17/02/2022 05:39, Dongliang Mu wrote:
> From: Dongliang Mu <mudongliangabcd@gmail.com>
>
> flush_work will throw one WARN if worker->func is NULL. So we should always
> initialize one worker before calling flush_work. When hdpvr_probe does not
> initialize its worker, the hdpvr_disconnect will encounter one WARN. The
> stack trace is in the following:
>
> hdpvr_disconnect+0xb8/0xf2 drivers/media/usb/hdpvr/hdpvr-core.c:425
> usb_unbind_interface+0xbf/0x3a0 drivers/usb/core/driver.c:458
> __device_release_driver drivers/base/dd.c:1206 [inline]
> device_release_driver_internal+0x22a/0x230 drivers/base/dd.c:1237
> bus_remove_device+0x108/0x160 drivers/base/bus.c:529
> device_del+0x1fe/0x510 drivers/base/core.c:3592
> usb_disable_device+0xd1/0x1d0 drivers/usb/core/message.c:1419
> usb_disconnect+0x109/0x330 drivers/usb/core/hub.c:2228
>
> Fix this by adding a sanity check of the worker before flush_work.
>
> Reported-by: syzkaller <syzkaller@googlegroups.com>
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> ---
> drivers/media/usb/hdpvr/hdpvr-core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/hdpvr/hdpvr-core.c b/drivers/media/usb/hdpvr/hdpvr-core.c
> index 52e05a69c46e..d102b459d45d 100644
> --- a/drivers/media/usb/hdpvr/hdpvr-core.c
> +++ b/drivers/media/usb/hdpvr/hdpvr-core.c
> @@ -422,7 +422,8 @@ static void hdpvr_disconnect(struct usb_interface *interface)
> mutex_unlock(&dev->io_mutex);
> v4l2_device_disconnect(&dev->v4l2_dev);
> msleep(100);
> - flush_work(&dev->worker);
> + if (dev->worker.func)
> + flush_work(&dev->worker);
I don't think this is the right fix. Instead, move the INIT_WORK line from
hdpvr_start_streaming() to hdpvr_register_videodev(). That should initialize
the worker struct from the start instead of only when you start streaming,
as is the case today.
Can you try that?
Regards,
Hans
> mutex_lock(&dev->io_mutex);
> hdpvr_cancel_queue(dev);
> mutex_unlock(&dev->io_mutex);
next prev parent reply other threads:[~2022-02-17 12:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-17 4:39 [PATCH] media: hdpvr: call flush_work only if initialized Dongliang Mu
2022-02-17 12:05 ` Hans Verkuil [this message]
2022-02-18 5:58 ` Dongliang Mu
2022-02-18 8:03 ` Hans Verkuil
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b452f7a7-99fa-e023-9120-639b4110de73@xs4all.nl \
--to=hverkuil@xs4all.nl \
--cc=dzm91@hust.edu.cn \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@kernel.org \
--cc=mudongliangabcd@gmail.com \
--cc=syzkaller@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).