From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03118225D6; Sun, 16 Jun 2024 23:54:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718582075; cv=none; b=QGXiCcpssx0fBchyn+uvJQyToqxnI4qEa0ZO/k2mRe14bq7ur41Dq6rIfvmo8Mi3ziRqGxkCcTCGIbjuxuUI2kTviLV4gJzo7E4Yj2M5Fzhi7qFihpAdMhSyMetJxcLRtjIUCEehF2O48FS39qmemOwjPRyJ8JilhtHlU3IzVv0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718582075; c=relaxed/simple; bh=Ri2CvSvGdxzAt/3LSCYExptWawOTSqNiyOXzVHotLCM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aIVuiJimF2ZS/7b/7iGEubMor+sWZ/1rscC/kx4p+Um+iAusOBm7BvhCIsbQ/G1UciexXDzd/gtPiCOnjSOieqFP/eMswcFgZXepIp+dMtsOQ+1vquC6U4g8Qxvha9egaJoow2/0APPfJ1fDALup0RHGnx5OvGjOfBn3JWg2TAU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=vt3MdcV1; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="vt3MdcV1" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id DCC412D5; Mon, 17 Jun 2024 01:54:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1718582056; bh=Ri2CvSvGdxzAt/3LSCYExptWawOTSqNiyOXzVHotLCM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vt3MdcV1rkaAu86FddoUKH5fcocyXobZ0CorVlmNQmAEILWuYP+Leah3NU9MVvSDs Ntj4TiRA86iYqBAsGptIue5kpIhHCmgmrjoqRL7Kz9GLVFX6SnayZRoBkZrJNAUBPa XNMOGoihnZafieiGrVTYQweeIsdoiFBbS6xAxrT4= Date: Mon, 17 Jun 2024 02:54:10 +0300 From: Laurent Pinchart To: Ricardo Ribalda Cc: Mauro Carvalho Chehab , Guenter Roeck , Tomasz Figa , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Sakari Ailus Subject: Re: [PATCH v6 1/4] media: uvcvideo: Stop stream during unregister Message-ID: <20240616235410.GN4782@pendragon.ideasonboard.com> References: <20240614-guenter-mini-v6-0-7b7fdc3b21b3@chromium.org> <20240614-guenter-mini-v6-1-7b7fdc3b21b3@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240614-guenter-mini-v6-1-7b7fdc3b21b3@chromium.org> Hi Ricardo, Thank you for the patch. On Fri, Jun 14, 2024 at 12:41:27PM +0000, Ricardo Ribalda wrote: > uvc_unregister_video() can be called asynchronously from > uvc_disconnect(). If the device is still streaming when that happens, a > plethora of race conditions can occur. > > Make sure that the device has stopped streaming before exiting this > function. > > If the user still holds handles to the driver's file descriptors, any > ioctl will return -ENODEV from the v4l2 core. > > This change makes uvc more consistent with the rest of the v4l2 drivers > using the vb2_fop_* and vb2_ioctl_* helpers. As I've said many times before, this issue needs a fix in the V4L2 core, ideally with support in the cdev core. It seems I'll have to do it myself ? > Reviewed-by: Hans Verkuil > Suggested-by: Hans Verkuil > Signed-off-by: Ricardo Ribalda > --- > drivers/media/usb/uvc/uvc_driver.c | 32 +++++++++++++++++++++++++++++++- > 1 file changed, 31 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > index bbd90123a4e7..55132688e363 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -1908,11 +1908,41 @@ static void uvc_unregister_video(struct uvc_device *dev) > struct uvc_streaming *stream; > > list_for_each_entry(stream, &dev->streams, list) { > + /* Nothing to do here, continue. */ > if (!video_is_registered(&stream->vdev)) > continue; > > + /* > + * For stream->vdev we follow the same logic as: > + * vb2_video_unregister_device(). > + */ > + > + /* 1. Take a reference to vdev */ > + get_device(&stream->vdev.dev); > + > + /* 2. Ensure that no new ioctls can be called. */ > video_unregister_device(&stream->vdev); > - video_unregister_device(&stream->meta.vdev); > + > + /* 3. Wait for old ioctls to finish. */ > + mutex_lock(&stream->mutex); > + > + /* 4. Stop streaming. */ > + uvc_queue_release(&stream->queue); > + > + mutex_unlock(&stream->mutex); > + > + put_device(&stream->vdev.dev); > + > + /* > + * For stream->meta.vdev we can directly call: > + * vb2_video_unregister_device(). > + */ > + vb2_video_unregister_device(&stream->meta.vdev); > + > + /* > + * Now both vdevs are not streaming and all the ioctls will > + * return -ENODEV. > + */ > > uvc_debugfs_cleanup_stream(stream); > } -- Regards, Laurent Pinchart