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Tue, 13 Dec 2022 06:36:02 -0800 (PST) Received: from alco.roam.corp.google.com ([100.104.168.209]) by smtp.gmail.com with ESMTPSA id kv17-20020a17090778d100b00781dbdb292asm4613960ejc.155.2022.12.13.06.36.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 06:36:02 -0800 (PST) From: Ricardo Ribalda Date: Tue, 13 Dec 2022 15:35:30 +0100 Subject: [PATCH v2 1/2] media: uvcvideo: Fix race condition with usb_kill_urb MIME-Version: 1.0 Message-Id: <20221212-uvc-race-v2-1-54496cc3b8ab@chromium.org> References: <20221212-uvc-race-v2-0-54496cc3b8ab@chromium.org> In-Reply-To: <20221212-uvc-race-v2-0-54496cc3b8ab@chromium.org> To: Max Staudt , Sergey Senozhatsky , Yunke Cao , Laurent Pinchart , Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Ricardo Ribalda X-Mailer: b4 0.11.0-dev-696ae X-Developer-Signature: v=1; a=openpgp-sha256; l=3069; i=ribalda@chromium.org; h=from:subject:message-id; bh=6kvmCn7eEeTM0+R88QPjF6t0UZo7MMe7Xr8f2IbHo6E=; 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For UVC, the function uvc_ctrl_status_event_async() takes care of control changes asynchronously. If the code is executed in the following order: CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_ctrl_status_event_work() uvc_status_start() -> FAIL Then uvc_status_start will keep failing and this error will be shown: <4>[ 5.540139] URB 0000000000000000 submitted while active drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528 Let's improve the current situation, by not re-submiting the urb if we are stopping the status event. Also process the queued work (if any) during stop. CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_status_start() uvc_ctrl_status_event_work() -> FAIL Hopefully, with the usb layer protection this should be enough to cover all the cases. Cc: stable@vger.kernel.org Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Signed-off-by: Ricardo Ribalda Reviewed-by: Yunke Cao --- drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ drivers/media/usb/uvc/uvc_status.c | 6 ++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 10 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index c95a2229f4fa..5160facc8e20 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1442,6 +1442,9 @@ static void uvc_ctrl_status_event_work(struct work_struct *work) uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + if (dev->flush_status) + return; + /* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret = usb_submit_urb(w->urb, GFP_KERNEL); diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 7518ffce22ed..09a5802dc974 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -304,10 +304,16 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags) if (dev->int_urb == NULL) return 0; + dev->flush_status = false; return usb_submit_urb(dev->int_urb, flags); } void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w = &dev->async_ctrl; + + dev->flush_status = true; usb_kill_urb(dev->int_urb); + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index df93db259312..6a9b72d6789e 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -560,6 +560,7 @@ struct uvc_device { struct usb_host_endpoint *int_ep; struct urb *int_urb; u8 *status; + bool flush_status; struct input_dev *input; char input_phys[64];