Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755890Ab3DXAtQ (ORCPT ); Tue, 23 Apr 2013 20:49:16 -0400 Received: from mail-ye0-f201.google.com ([209.85.213.201]:61047 "EHLO mail-ye0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755069Ab3DXAtP (ORCPT ); Tue, 23 Apr 2013 20:49:15 -0400 From: Shawn Nematbakhsh To: Laurent Pinchart Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, shawnn@chromium.org Subject: [PATCH] [media] uvcvideo: Retry usb_submit_urb on -EPERM return Date: Tue, 23 Apr 2013 17:41:13 -0700 Message-Id: <1366764073-9633-1-git-send-email-shawnn@google.com> X-Mailer: git-send-email 1.8.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2366 Lines: 66 From: Shawn Nematbakhsh While usb_kill_urb is in progress, calls to usb_submit_urb will fail with -EPERM (documented in Documentation/usb/URB.txt). The UVC driver does not correctly handle this case -- there is no synchronization between uvc_v4l2_open / uvc_status_start and uvc_v4l2_release / uvc_status_stop. This patch adds a retry / timeout when uvc_status_open / usb_submit_urb returns -EPERM. This usually means that usb_kill_urb is in progress, and we just need to wait a while. Signed-off-by: Shawn Nematbakhsh --- drivers/media/usb/uvc/uvc_v4l2.c | 10 +++++++++- drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c index b2dc326..f1498a8 100644 --- a/drivers/media/usb/uvc/uvc_v4l2.c +++ b/drivers/media/usb/uvc/uvc_v4l2.c @@ -479,6 +479,7 @@ static int uvc_v4l2_open(struct file *file) { struct uvc_streaming *stream; struct uvc_fh *handle; + unsigned long timeout; int ret = 0; uvc_trace(UVC_TRACE_CALLS, "uvc_v4l2_open\n"); @@ -499,7 +500,14 @@ static int uvc_v4l2_open(struct file *file) } if (atomic_inc_return(&stream->dev->users) == 1) { - ret = uvc_status_start(stream->dev); + timeout = jiffies + msecs_to_jiffies(UVC_STATUS_START_TIMEOUT); + /* -EPERM means stop in progress, wait for completion */ + do { + ret = uvc_status_start(stream->dev); + if (ret == -EPERM) + usleep_range(5000, 6000); + } while (ret == -EPERM && time_before(jiffies, timeout)); + if (ret < 0) { atomic_dec(&stream->dev->users); usb_autopm_put_interface(stream->dev->intf); diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index af505fd..a47e1d3 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -122,6 +122,7 @@ #define UVC_CTRL_CONTROL_TIMEOUT 300 #define UVC_CTRL_STREAMING_TIMEOUT 5000 +#define UVC_STATUS_START_TIMEOUT 100 /* Maximum allowed number of control mappings per device */ #define UVC_MAX_CONTROL_MAPPINGS 1024 -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/