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spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727301AbeHHQJY (ORCPT ); Wed, 8 Aug 2018 12:09:24 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:59272 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726869AbeHHQJX (ORCPT ); Wed, 8 Aug 2018 12:09:23 -0400 Received: from [192.168.0.67] (cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id C074C57; Wed, 8 Aug 2018 15:49:34 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1533736175; bh=MkIZzjvCsp4pRt0NmJ9D5nN6+jnA+HlImudrZXFDlrU=; h=Reply-To:Subject:To:Cc:References:From:Date:In-Reply-To:From; b=PsmMvPrfmshXh9zJtQqfVzWTNlVeJLSoYI/OkMpbpADoS2hobiv1WtYNf3/0ngFC/ rV4su7jWSOXMcfDmBwTj5R9M4GDme+A4IH3n4GwoH/DAwbw5O2FsPDkivnYRIKy6Cs Jy4TP83g9bKoFC60ex0xs2heied5dYTKmFWriRHY= Reply-To: kieran.bingham@ideasonboard.com Subject: Re: [PATCH v4 6/6] media: uvcvideo: Move decode processing to process context To: Tomasz Figa Cc: Laurent Pinchart , Linux Media Mailing List , g.liakhovetski@gmx.de, olivier.braun@stereolabs.com, troy.kisky@boundarydevices.com, Randy Dunlap , philipp.zabel@gmail.com, Mauro Carvalho Chehab , Linux Kernel Mailing List References: From: Kieran Bingham Openpgp: preference=signencrypt Autocrypt: addr=kieran.bingham@ideasonboard.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tomasz, On 07/08/18 10:54, Tomasz Figa wrote: > Hi Kieran, > > On Wed, Mar 28, 2018 at 1:47 AM Kieran Bingham > wrote: > [snip] >> @@ -1544,25 +1594,29 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, >> */ >> static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers) >> { >> - struct urb *urb; >> - unsigned int i; >> + struct uvc_urb *uvc_urb; >> >> uvc_video_stats_stop(stream); >> >> - for (i = 0; i < UVC_URBS; ++i) { >> - struct uvc_urb *uvc_urb = &stream->uvc_urb[i]; >> + /* >> + * We must poison the URBs rather than kill them to ensure that even >> + * after the completion handler returns, any asynchronous workqueues >> + * will be prevented from resubmitting the URBs >> + */ >> + for_each_uvc_urb(uvc_urb, stream) >> + usb_poison_urb(uvc_urb->urb); >> >> - urb = uvc_urb->urb; >> - if (urb == NULL) >> - continue; >> + flush_workqueue(stream->async_wq); >> >> - usb_kill_urb(urb); >> - usb_free_urb(urb); >> + for_each_uvc_urb(uvc_urb, stream) { >> + usb_free_urb(uvc_urb->urb); >> uvc_urb->urb = NULL; >> } >> >> if (free_buffers) >> uvc_free_urb_buffers(stream); >> + >> + destroy_workqueue(stream->async_wq); > > In our testing, this function ends up being called twice, if before > suspend the camera is streaming and if the camera disconnects between > suspend and resume. This is because uvc_video_suspend() calls this > function (with free_buffers = 0), but uvc_video_resume() wouldn't call > uvc_init_video() due to an earlier failure and uvc_v4l2_release() > would end up calling this function again, while the workqueue is > already destroyed. > > The following diff seems to take care of it: Thank you for the investigation and patch report ;D I think moving the workqueue allocation might be a reasonable option as suggested by Laurent in his review. I'll look further into this when I get to another spin of the series. > > 8<~~~ > diff --git a/drivers/media/usb/uvc/uvc_video.c > b/drivers/media/usb/uvc/uvc_video.c > index c5e0ab564b1a..6fb890c8ba67 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -1493,10 +1493,11 @@ static void uvc_uninit_video(struct > uvc_streaming *stream, int free_buffers) > uvc_urb->urb = NULL; > } > > - if (free_buffers) > + if (free_buffers) { > uvc_free_urb_buffers(stream); > - > - destroy_workqueue(stream->async_wq); > + destroy_workqueue(stream->async_wq); > + stream->async_wq = NULL; > + } > } > > /* > @@ -1648,10 +1649,12 @@ static int uvc_init_video(struct uvc_streaming > *stream, gfp_t gfp_flags) > > uvc_video_stats_start(stream); > > - stream->async_wq = alloc_workqueue("uvcvideo", WQ_UNBOUND | WQ_HIGHPRI, > - 0); > - if (!stream->async_wq) > - return -ENOMEM; > + if (!stream->async_wq) { > + stream->async_wq = alloc_workqueue("uvcvideo", > + WQ_UNBOUND | WQ_HIGHPRI, 0); > + if (!stream->async_wq) > + return -ENOMEM; > + } > > if (intf->num_altsetting > 1) { > struct usb_host_endpoint *best_ep = NULL; > ~~~>8 > > Best regards, > Tomasz > -- Regards -- Kieran