From patchwork Tue Nov 21 19:53:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Ribalda X-Patchwork-Id: 745949 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="XF7p33qx" Received: from mail-qv1-xf35.google.com (mail-qv1-xf35.google.com [IPv6:2607:f8b0:4864:20::f35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B999619E for ; Tue, 21 Nov 2023 11:53:52 -0800 (PST) Received: by mail-qv1-xf35.google.com with SMTP id 6a1803df08f44-679f56c4707so569286d6.2 for ; Tue, 21 Nov 2023 11:53:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700596432; x=1701201232; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=dDCQx2svTZtfCmrCU69fY87fRl7Sd0hrHJUJrOpUR1s=; b=XF7p33qxwVcMCafNsYpOaqKk78Gm78d+4D54vMFD+yOprNN92MfBt03qzL5+F2jlz8 XWsvUjZ+hC/cHjadbCHNFi0qTjjg0IyjFvZDviirZnOF019Ew2SdDdTp8UyKPtg2efZV 1QM2scZ8t/DiL/HnvY62F/XIiPMfAdlzGjMQQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700596432; x=1701201232; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=dDCQx2svTZtfCmrCU69fY87fRl7Sd0hrHJUJrOpUR1s=; b=OmaRGwcv6aliQ50DSKYUPVhHl+iT8o5lbixZV4jH4TQfFJ2tsZaJEm09gY++F+SaqB vq1et/D8twT1OtZByG3dyAMmsapJhhwJRD7lbcFnLRWUAxhN4jlRfVZjaOCuNAYC58j6 G6Vp8STTflkIXvYSMWpVVjVlWht3/xc1zXzsHMpoy4Oc6e3D+8LTW1/GXkjPmabOSRTz mj1x2YnvRROmYsEj1jE/nicPcn8ENW/hTPjllefdbB757pCC/ddGRuHPPC7G5IijUIA3 V+h9f/9z1rN3fPQw1M58KHUTs71Y9gyvSFbkzOwVGLmhfIJtEaXvkYDt8iobvT3OzsLR 88MA== X-Gm-Message-State: AOJu0Yy/HCVUoU9cCuclfAgfTvBMvBn0KDmVYiriYbiNzl/EUGGTTGFh Sh7H+QUzOyRztl+jz2GRPLoeBQ== X-Google-Smtp-Source: AGHT+IF+lZdugSOktq4NX5eTYkUsxrmRa17an3i9t4gdkRbjS4TnOQljcMe6VQLkna5ICl+GoJLspg== X-Received: by 2002:a05:6214:21e2:b0:66d:2d07:eab4 with SMTP id p2-20020a05621421e200b0066d2d07eab4mr51485qvj.42.1700596431833; Tue, 21 Nov 2023 11:53:51 -0800 (PST) Received: from denia.c.googlers.com (228.221.150.34.bc.googleusercontent.com. [34.150.221.228]) by smtp.gmail.com with ESMTPSA id ct2-20020a056214178200b0065b0d9b4ee7sm4199409qvb.20.2023.11.21.11.53.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Nov 2023 11:53:51 -0800 (PST) From: Ricardo Ribalda Date: Tue, 21 Nov 2023 19:53:48 +0000 Subject: [PATCH v3 1/3] media: uvcvideo: Always use uvc_status_stop() Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231121-guenter-mini-v3-1-d8a5eae2312b@chromium.org> References: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> In-Reply-To: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> To: Mauro Carvalho Chehab Cc: Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Ricardo Ribalda , Sakari Ailus X-Mailer: b4 0.12.3 uvc_status_stop() handles properly the race conditions with the asynchronous worker. Let's use uvc_status_stop() for all the code paths that require stopping it. Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_ctrl.c | 4 ---- drivers/media/usb/uvc/uvc_status.c | 2 +- 2 files changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index e59a463c2761..8e22a07e3e7b 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -2765,10 +2765,6 @@ void uvc_ctrl_cleanup_device(struct uvc_device *dev) struct uvc_entity *entity; unsigned int i; - /* Can be uninitialized if we are aborting on probe error. */ - if (dev->async_ctrl.work.func) - cancel_work_sync(&dev->async_ctrl.work); - /* Free controls and control mappings for all entities. */ list_for_each_entry(entity, &dev->entities, list) { for (i = 0; i < entity->ncontrols; ++i) { diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index a78a88c710e2..0208612a9f12 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -292,7 +292,7 @@ int uvc_status_init(struct uvc_device *dev) void uvc_status_unregister(struct uvc_device *dev) { - usb_kill_urb(dev->int_urb); + uvc_status_stop(dev); uvc_input_unregister(dev); } From patchwork Tue Nov 21 19:53:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Ribalda X-Patchwork-Id: 746360 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Crb37cSy" Received: from mail-qv1-xf29.google.com (mail-qv1-xf29.google.com [IPv6:2607:f8b0:4864:20::f29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD9AD1A1 for ; Tue, 21 Nov 2023 11:53:53 -0800 (PST) Received: by mail-qv1-xf29.google.com with SMTP id 6a1803df08f44-677f974b72bso20598426d6.3 for ; Tue, 21 Nov 2023 11:53:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700596433; x=1701201233; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=b3dKWWo3LzCAEQiNhkIr0MWg5E8+oPU3fVyqu1x1TiE=; b=Crb37cSysZk6ssFT2wZzBeAY6UFXgEeq++bTqg3NCWi0s9fVENA2fd0ArX7nF9/fIB GaVviUbqaOP8xOkiA3MtM4K3BvGwMY4jxhVBuzkC91ri27vfI8jUpOdj+zD4ICeMCin7 y6rO7sThVd/sf6pl3ZVRfF0TukWq6UzT/rVXw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700596433; x=1701201233; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=b3dKWWo3LzCAEQiNhkIr0MWg5E8+oPU3fVyqu1x1TiE=; b=mIhg1Rpc1sKDzcVliHo+abzNNwIWY/X4+YnI1OHePhbpwzczJZcV7DLqzY38esyGtm qA7nVnh8boZTZ5bnFQ607Mwdsp2JKU/yAzO5Uc89FzN7Gra329PtvjcOVbVq320b9Fcf o3vtuwF0nKJrxMW9M57AbPlCIFBjEzPCIh2qg8w3luTAwsCvRQ0aIKaeO51yBwtInQqm z9BPeAu9JQMYsrKmD4rs3mndAjo+Gf2sfmBKRLwSHd52x2k8GdSowV1JCvzE6oyTyyrE T9e4gseyGfVez5BqMOkS0eI8KusLTVRV/bALp5VkfC+f5vNq3Tm971+DqqRYq/cMisuQ oyug== X-Gm-Message-State: AOJu0YzRbSGMAynnxa3FVqZgYd4o+nwKJVKOjacgTEWf7Wgcgf1HUpiz 7rC95G/8vh/EEVVgEGitpaGRtQ== X-Google-Smtp-Source: AGHT+IH4iZm8S/Q3/lVNTg9M6/32O3nNoVgDmsM5sk/1xQgXoqisut02jXqvXhdJwiN7ODhbs0v01A== X-Received: by 2002:a05:6214:2341:b0:675:65d6:d0f3 with SMTP id hu1-20020a056214234100b0067565d6d0f3mr77672qvb.24.1700596432960; Tue, 21 Nov 2023 11:53:52 -0800 (PST) Received: from denia.c.googlers.com (228.221.150.34.bc.googleusercontent.com. [34.150.221.228]) by smtp.gmail.com with ESMTPSA id ct2-20020a056214178200b0065b0d9b4ee7sm4199409qvb.20.2023.11.21.11.53.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Nov 2023 11:53:52 -0800 (PST) From: Ricardo Ribalda Date: Tue, 21 Nov 2023 19:53:49 +0000 Subject: [PATCH v3 2/3] media: uvcvideo: Do not halt the device after disconnect Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231121-guenter-mini-v3-2-d8a5eae2312b@chromium.org> References: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> In-Reply-To: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> To: Mauro Carvalho Chehab Cc: Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Ricardo Ribalda , Sakari Ailus X-Mailer: b4 0.12.3 usb drivers should not call to any usb_() function after the .disconnect() callback has been triggered. If the camera is streaming, the uvc driver will call usb_set_interface or usb_clear_halt once the device is being released. Let's fix this issue. This is probably not the only driver affected with this kind of bug, but until there is a better way to do it in the core this is the way to solve this issue. When/if a different mechanism is implemented in the core to solve the lifetime of devices we will adopt it in uvc. Trace: [ 1065.389723] drivers/media/usb/uvc/uvc_driver.c:2248 uvc_disconnect enter [ 1065.390160] drivers/media/usb/uvc/uvc_driver.c:2264 uvc_disconnect exit [ 1065.433956] drivers/media/usb/uvc/uvc_v4l2.c:659 uvc_v4l2_release enter [ 1065.433973] drivers/media/usb/uvc/uvc_video.c:2274 uvc_video_stop_streaming enter [ 1065.434560] drivers/media/usb/uvc/uvc_video.c:2285 uvc_video_stop_streaming exit [ 1065.435154] drivers/media/usb/uvc/uvc_v4l2.c:680 uvc_v4l2_release exit [ 1065.435188] drivers/media/usb/uvc/uvc_driver.c:2248 uvc_disconnect enter Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_driver.c | 2 ++ drivers/media/usb/uvc/uvc_video.c | 45 ++++++++++++++++++++++++-------------- drivers/media/usb/uvc/uvcvideo.h | 2 ++ 3 files changed, 32 insertions(+), 17 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index 08fcd2ffa727..413c32867617 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2257,6 +2257,8 @@ static void uvc_disconnect(struct usb_interface *intf) return; uvc_unregister_video(dev); + /* Barrier needed to synchronize with uvc_video_stop_streaming(). */ + smp_store_release(&dev->disconnected, true); kref_put(&dev->ref, uvc_delete); } diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index 28dde08ec6c5..032b44e45b22 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -2243,28 +2243,39 @@ int uvc_video_start_streaming(struct uvc_streaming *stream) return ret; } -void uvc_video_stop_streaming(struct uvc_streaming *stream) +static void uvc_video_halt(struct uvc_streaming *stream) { - uvc_video_stop_transfer(stream, 1); + unsigned int epnum; + unsigned int pipe; + unsigned int dir; if (stream->intf->num_altsetting > 1) { usb_set_interface(stream->dev->udev, stream->intfnum, 0); - } else { - /* - * UVC doesn't specify how to inform a bulk-based device - * when the video stream is stopped. Windows sends a - * CLEAR_FEATURE(HALT) request to the video streaming - * bulk endpoint, mimic the same behaviour. - */ - unsigned int epnum = stream->header.bEndpointAddress - & USB_ENDPOINT_NUMBER_MASK; - unsigned int dir = stream->header.bEndpointAddress - & USB_ENDPOINT_DIR_MASK; - unsigned int pipe; - - pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir; - usb_clear_halt(stream->dev->udev, pipe); + return; } + /* + * UVC doesn't specify how to inform a bulk-based device + * when the video stream is stopped. Windows sends a + * CLEAR_FEATURE(HALT) request to the video streaming + * bulk endpoint, mimic the same behaviour. + */ + epnum = stream->header.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK; + dir = stream->header.bEndpointAddress & USB_ENDPOINT_DIR_MASK; + pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir; + usb_clear_halt(stream->dev->udev, pipe); +} + +void uvc_video_stop_streaming(struct uvc_streaming *stream) +{ + uvc_video_stop_transfer(stream, 1); + + /* + * Barrier needed to synchronize with uvc_disconnect(). + * We cannot call usb_* functions on a disconnected USB device. + */ + if (!smp_load_acquire(&stream->dev->disconnected)) + uvc_video_halt(stream); + uvc_video_clock_cleanup(stream); } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index 6fb0a78b1b00..4318ce8e31db 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -559,6 +559,8 @@ struct uvc_device { unsigned int users; atomic_t nmappings; + bool disconnected; + /* Video control interface */ #ifdef CONFIG_MEDIA_CONTROLLER struct media_device mdev; From patchwork Tue Nov 21 19:53:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Ribalda X-Patchwork-Id: 745948 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="mVJnvzEg" Received: from mail-ot1-x333.google.com (mail-ot1-x333.google.com [IPv6:2607:f8b0:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96A44191 for ; Tue, 21 Nov 2023 11:53:54 -0800 (PST) Received: by mail-ot1-x333.google.com with SMTP id 46e09a7af769-6d7e56f6845so447022a34.0 for ; Tue, 21 Nov 2023 11:53:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700596434; x=1701201234; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=vBBR3Lb8+qLiLMbc/jEnU4Lx/0wS0LihO+fwyf1YUqQ=; b=mVJnvzEgvHgTXvGHTkIA53uO+Ifdo3TgXxNPsUo7sb4BRl2+BghrRSdPx5Itbp8EVF 7FdkBg+7JcCw+Y8PTu4vxCcF5ADjPPRslOEWwgdAcjDBEJBlzSse6WWJPzoIzemABcgC HRuV09zfPV86dCbLDhPqVwHSd5tzUb70pWu4w= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700596434; x=1701201234; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vBBR3Lb8+qLiLMbc/jEnU4Lx/0wS0LihO+fwyf1YUqQ=; b=U0VMd0D9Fzp/iXrMLtY+hoMigKnkDY2bMP3oUDVOvy84yZXF2E0UyLyjwk4tNk7/Zg Xa8hichHGy5S2lMVcub8G6kaDhPXFspaqdEByPlJMaloT0a0nNYdGqanUfwdhmk+J7t8 hZ14FyAPx2GbEXdLaOPFYxuWxJM2j+KCWgu2QOPz4s1RbIPSh5gUkX5txIZOLLaEKHd/ kAghVrzOERoQQ2tKBlvon62LT1v85uIUMrxGKbdJi8EO1IbVpiPyP11KnHSkBTy2PsSz 38oftCJO3ivywqw40eOH0ZPAlwB3WlwZkZfCCV76e/DaV4QPPGABvSrRhf8aQqlQfi9S JpkQ== X-Gm-Message-State: AOJu0YxeKa6/UjgBjMuCZ+4OccujXFs4PHM/uSbB3GtTRONkuPdzCFNM mGTGAv0rKux99AH6QXR7J2xxKw== X-Google-Smtp-Source: AGHT+IHB81wHsX96Couk1aRPcExkFua5WXgh+OpUbktLI410dXLaqQdYl/czRy+2ofoE2m4aEMetUw== X-Received: by 2002:a05:6830:39cc:b0:6d6:4c25:5a56 with SMTP id bt12-20020a05683039cc00b006d64c255a56mr325498otb.12.1700596433867; Tue, 21 Nov 2023 11:53:53 -0800 (PST) Received: from denia.c.googlers.com (228.221.150.34.bc.googleusercontent.com. [34.150.221.228]) by smtp.gmail.com with ESMTPSA id ct2-20020a056214178200b0065b0d9b4ee7sm4199409qvb.20.2023.11.21.11.53.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Nov 2023 11:53:53 -0800 (PST) From: Ricardo Ribalda Date: Tue, 21 Nov 2023 19:53:50 +0000 Subject: [PATCH v3 3/3] media: uvcvideo: Lock video streams and queues while unregistering Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231121-guenter-mini-v3-3-d8a5eae2312b@chromium.org> References: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> In-Reply-To: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> To: Mauro Carvalho Chehab Cc: Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Ricardo Ribalda , Sakari Ailus X-Mailer: b4 0.12.3 From: Guenter Roeck The call to uvc_disconnect() is not protected by any mutex. This means it can and will be called while other accesses to the video device are in progress. This can cause all kinds of race conditions, including crashes such as the following. usb 1-4: USB disconnect, device number 3 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 5633 Comm: V4L2CaptureThre Not tainted 4.19.113-08536-g5d29ca36db06 #1 Hardware name: GOOGLE Edgar, BIOS Google_Edgar.7287.167.156 03/25/2019 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:0000000000000000 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 usb_set_interface() should not be called after the USB device has been unregistered. However, in the above case the disconnect happened after v4l2_ioctl() was called, but before the call to usb_ifnum_to_if(). Acquire various mutexes in uvc_unregister_video() to fix the majority (maybe all) of the observed race conditions. The uvc_device lock prevents races against suspend and resume calls and the poll function. The uvc_streaming lock prevents races against stream related functions; for the most part, those are ioctls. This lock also requires other functions using this lock to check if a video device is still registered after acquiring it. For example, it was observed that the video device was already unregistered by the time the stream lock was acquired in uvc_ioctl_streamon(). The uvc_queue lock prevents races against queue functions, Most of those are already protected by the uvc_streaming lock, but some are called directly. This is done as added protection; an actual race was not (yet) observed. Cc: Laurent Pinchart Cc: Alan Stern Cc: Hans Verkuil Reviewed-by: Tomasz Figa Reviewed-by: Sean Paul Signed-off-by: Guenter Roeck Signed-off-by: Ricardo Ribalda --- drivers/media/usb/uvc/uvc_driver.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index 413c32867617..3408b865d346 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1907,14 +1907,22 @@ static void uvc_unregister_video(struct uvc_device *dev) { struct uvc_streaming *stream; + mutex_lock(&dev->lock); + list_for_each_entry(stream, &dev->streams, list) { if (!video_is_registered(&stream->vdev)) continue; + mutex_lock(&stream->mutex); + mutex_lock(&stream->queue.mutex); + video_unregister_device(&stream->vdev); video_unregister_device(&stream->meta.vdev); uvc_debugfs_cleanup_stream(stream); + + mutex_unlock(&stream->queue.mutex); + mutex_unlock(&stream->mutex); } uvc_status_unregister(dev); @@ -1925,6 +1933,7 @@ static void uvc_unregister_video(struct uvc_device *dev) if (media_devnode_is_registered(dev->mdev.devnode)) media_device_unregister(&dev->mdev); #endif + mutex_unlock(&dev->lock); } int uvc_register_video_device(struct uvc_device *dev,