From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF0CFC32774 for ; Tue, 23 Aug 2022 09:34:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351062AbiHWJeA (ORCPT ); Tue, 23 Aug 2022 05:34:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350721AbiHWJcm (ORCPT ); Tue, 23 Aug 2022 05:32:42 -0400 Received: from mail-yw1-x112a.google.com (mail-yw1-x112a.google.com [IPv6:2607:f8b0:4864:20::112a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1018674CC1 for ; Tue, 23 Aug 2022 01:38:51 -0700 (PDT) Received: by mail-yw1-x112a.google.com with SMTP id 00721157ae682-32a09b909f6so361086377b3.0 for ; Tue, 23 Aug 2022 01:38:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=semihalf.com; s=google; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc; bh=cgc+e/QzNdyD2sfucJY+c/VRbtSyirfoyG9awCiqMa4=; b=kUrFjIHECTaBr9+CKEUTz4OLFtxjYaXXGh+DIth9fw223PK1yidFfqVYBKotKgREon rn0SdwopAWDltNNwEtcw8x2F4jYDo+6O72ACtJg7eBBRL/AtQFzIr6nPHvoVFHuF6wWG 46gE7n2khQGERr18D6bX/yfDzzeEfTcEyt3a4PX0Lpn8i8eI2QGzBb1k1k5n+VLPfqmT gSrfA521jCdxvgWL9H8ZopNm35pxb0KtwT0tRmg2ex7JMIFXZiYCZUrsbBv3K3M4IqNV wgimq51IM18LsFVOViGgvdqQzAZsqDCvnWjnghr+KMQxIUS2HTY1R+lgifuQMzMiyfA2 UU8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc; bh=cgc+e/QzNdyD2sfucJY+c/VRbtSyirfoyG9awCiqMa4=; b=QV/YwPYi6v3U2eibIUFiiunBhbkKztxH4u5e/2dbSE+yVI1pNLYCspVxUM3SUhUCoJ I4qxsnFLXXOaj6WCXssArPEB7a/iU4uS8RIKheArxaxvkr+qrbANWcv2UbmN7ttuNg9B yXU7w1ke7TRrE4Ed9GIGgE07lzBku9oLUkYGXoPD2d5Sx/J6iqr6/1jK7kQKu72q3UjC ZUqOMV8R3/jYGYguLahvhHRf8QeFtDSBZxV/ZQkDbXGf5XFlViLLhwsdRQYcSDLEBh/i /xiK1Z7w2YzpAZGpQYCL0q+vdHnsUguya/E0zkabe4PTNzj015SyPJqRBA46DvaiRDoG clXw== X-Gm-Message-State: ACgBeo3Q0/CUFQyBW/IvtCMuqN5W442mRCPfG0uohUPwu2xiTyiK96IO WKwYUYJsB3rUlTb5azxzM7LHsVEBDWAC/ovZmJ0fsQ== X-Google-Smtp-Source: AA6agR5Cgtu718MiKMVY1/XiyInsuBVJHNdFRsvSqTrNoHkmhAshU/tLTB8cZgDu+q0Z/EZnw0wrJC4b3x0GnuHi6qs= X-Received: by 2002:a05:6902:387:b0:694:159f:ad3c with SMTP id f7-20020a056902038700b00694159fad3cmr20730903ybs.223.1661243870140; Tue, 23 Aug 2022 01:37:50 -0700 (PDT) MIME-Version: 1.0 References: <20200917022547.198090-1-linux@roeck-us.net> <20220311202426.GE23776@pengutronix.de> In-Reply-To: From: Lukasz Majczak Date: Tue, 23 Aug 2022 10:37:39 +0200 Message-ID: Subject: Re: [PATCH RESEND v3 0/5] media: uvcvideo: Fix race conditions To: Laurent Pinchart Cc: Michael Grzeschik , Guenter Roeck , Mauro Carvalho Chehab , Sakari Ailus , linux-uvc-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, linux-media@vger.kernel.org, LKML Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org sob., 12 mar 2022 o 19:43 Laurent Pinchart napisa=C5=82(a): > > Hi Michael, > > On Fri, Mar 11, 2022 at 09:24:26PM +0100, Michael Grzeschik wrote: > > Ping! > > > > This series seems to be hanging around. It would be nice to get these > > patches upstream, as they help my uvc-gadget workflow. Without them it > > is likely that in the development cases my gadget won't start and then > > leave the whole xhci controller broken. > > > > @Laurent, what do you think? > > I think I've explained before how this should be fixed at the V4L2 > level. The problem actually affects character devices globally, and Greg > KH said he would have a go at fixing it there, but I don't think much > happened. Starting with a V4L2-level fix is fine with me. > > There are a few patches in the series that are specific to uvcvideo, > I'll have another look and merge those. > > > On Wed, Sep 16, 2020 at 07:25:42PM -0700, Guenter Roeck wrote: > > > Something seems to have gone wrong with v3 of this patch series. > > > I am sure I sent it out, but I don't find it anywhere. > > > Resending. Sorry for any duplicates. > > > > > > The uvcvideo code has no lock protection against USB disconnects > > > while video operations are ongoing. This has resulted in random > > > error reports, typically pointing to a crash in usb_ifnum_to_if(), > > > called from usb_hcd_alloc_bandwidth(). A typical traceback is as > > > follows. > > > > > > usb 1-4: USB disconnect, device number 3 > > > BUG: unable to handle kernel NULL pointer dereference at 000000000000= 0000 > > > PGD 0 P4D 0 > > > Oops: 0000 [#1] PREEMPT SMP PTI > > > CPU: 0 PID: 5633 Comm: V4L2CaptureThre Not tainted 4.19.113-08536-g5d= 29ca36db06 #1 > > > Hardware name: GOOGLE Edgar, BIOS Google_Edgar.7287.167.156 03/25/201= 9 > > > RIP: 0010:usb_ifnum_to_if+0x29/0x40 > > > Code: <...> > > > RSP: 0018:ffffa46f42a47a80 EFLAGS: 00010246 > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff904a396c9000 > > > RDX: ffff904a39641320 RSI: 0000000000000001 RDI: 0000000000000000 > > > RBP: ffffa46f42a47a80 R08: 0000000000000002 R09: 0000000000000000 > > > R10: 0000000000009975 R11: 0000000000000009 R12: 0000000000000000 > > > R13: ffff904a396b3800 R14: ffff904a39e88000 R15: 0000000000000000 > > > FS: 00007f396448e700(0000) GS:ffff904a3ba00000(0000) knlGS:0000000000= 000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 0000000000000000 CR3: 000000016cb46000 CR4: 00000000001006f0 > > > Call Trace: > > > usb_hcd_alloc_bandwidth+0x1ee/0x30f > > > usb_set_interface+0x1a3/0x2b7 > > > uvc_video_start_transfer+0x29b/0x4b8 [uvcvideo] > > > uvc_video_start_streaming+0x91/0xdd [uvcvideo] > > > uvc_start_streaming+0x28/0x5d [uvcvideo] > > > vb2_start_streaming+0x61/0x143 [videobuf2_common] > > > vb2_core_streamon+0xf7/0x10f [videobuf2_common] > > > uvc_queue_streamon+0x2e/0x41 [uvcvideo] > > > uvc_ioctl_streamon+0x42/0x5c [uvcvideo] > > > __video_do_ioctl+0x33d/0x42a > > > video_usercopy+0x34e/0x5ff > > > ? video_ioctl2+0x16/0x16 > > > v4l2_ioctl+0x46/0x53 > > > do_vfs_ioctl+0x50a/0x76f > > > ksys_ioctl+0x58/0x83 > > > __x64_sys_ioctl+0x1a/0x1e > > > do_syscall_64+0x54/0xde > > > > > > While there are not many references to this problem on mailing lists,= it is > > > reported on a regular basis on various Chromebooks (roughly 300 repor= ts > > > per month). The problem is relatively easy to reproduce by adding msl= eep() > > > calls into the code. > > > > > > I tried to reproduce the problem with non-uvcvideo webcams, but was > > > unsuccessful. I was unable to get Philips (pwc) webcams to work. gspc= a > > > based webcams don't experience the problem, or at least I was unable = to > > > reproduce it (The gspa driver does not trigger sending USB messages i= n the > > > open function, and otherwise uses the locking mechanism provided by t= he > > > v4l2/vb2 core). > > > > > > I don't presume to claim that I found every issue, but this patch ser= ies > > > should fix at least the major problems. > > > > > > The patch series was tested exensively on a Chromebook running chrome= os-4.19 > > > and on a Linux system running a v5.8.y based kernel. > > > > > > v3: > > > - In patch 5/5, add missing calls to usb_autopm_put_interface() and k= free() > > > to failure code path > > > > > > v2: > > > - Added details about problem frequency and testing with non-uvc webc= ams > > > to summary > > > - In patch 4/5, return EPOLLERR instead of -ENODEV on poll errors > > > - Fix description in patch 5/5 > > > > > > ---------------------------------------------------------------- > > > Guenter Roeck (5): > > > media: uvcvideo: Cancel async worker earlier > > > media: uvcvideo: Lock video streams and queues while unregister= ing > > > media: uvcvideo: Release stream queue when unregistering video = device > > > media: uvcvideo: Protect uvc queue file operations against disc= onnect > > > media: uvcvideo: Abort uvc_v4l2_open if video device is unregis= tered > > > > > > drivers/media/usb/uvc/uvc_ctrl.c | 11 ++++++---- > > > drivers/media/usb/uvc/uvc_driver.c | 12 ++++++++++ > > > drivers/media/usb/uvc/uvc_queue.c | 32 +++++++++++++++++++++++++-- > > > drivers/media/usb/uvc/uvc_v4l2.c | 45 ++++++++++++++++++++++++++++= ++++++++-- > > > drivers/media/usb/uvc/uvcvideo.h | 1 + > > > 5 files changed, 93 insertions(+), 8 deletions(-) > > -- > Regards, > > Laurent Pinchart Hi Laurent, Have you had time to take another look at those patches? Can we somehow move at least with the uvcvideo patches? Best regards, Lukasz