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Message-Id: <20190124190214.539167670@linuxfoundation.org>
Date: Thu, 24 Jan 2019 20:20:01 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Daniel Axtens <dja@...ens.net>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.20 055/127] media: uvcvideo: Refactor teardown of uvc on USB disconnect
4.20-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit 10e1fdb95809ed21406f53b5b4f064673a1b9ceb ]
Currently, disconnecting a USB webcam while it is in use prints out a
number of warnings, such as:
WARNING: CPU: 2 PID: 3118 at /build/linux-ezBi1T/linux-4.8.0/fs/sysfs/group.c:237 sysfs_remove_group+0x8b/0x90
sysfs group ffffffffa7cd0780 not found for kobject 'event13'
This has been noticed before. [0]
This is because of the order in which things are torn down.
If there are no streams active during a USB disconnect:
- uvc_disconnect() is invoked via device_del() through the bus
notifier mechanism.
- this calls uvc_unregister_video().
- uvc_unregister_video() unregisters the video device for each
stream,
- because there are no streams open, it calls uvc_delete()
- uvc_delete() calls uvc_status_cleanup(), which cleans up the status
input device.
- uvc_delete() calls media_device_unregister(), which cleans up the
media device
- uvc_delete(), uvc_unregister_video() and uvc_disconnect() all
return, and we end up back in device_del().
- device_del() then cleans up the sysfs folder for the camera with
dpm_sysfs_remove(). Because uvc_status_cleanup() and
media_device_unregister() have already been called, this all works
nicely.
If, on the other hand, there *are* streams active during a USB disconnect:
- uvc_disconnect() is invoked
- this calls uvc_unregister_video()
- uvc_unregister_video() unregisters the video device for each
stream,
- uvc_unregister_video() and uvc_disconnect() return, and we end up
back in device_del().
- device_del() then cleans up the sysfs folder for the camera with
dpm_sysfs_remove(). Because the status input device and the media
device are children of the USB device, this also deletes their
sysfs folders.
- Sometime later, the final stream is closed, invoking uvc_release().
- uvc_release() calls uvc_delete()
- uvc_delete() calls uvc_status_cleanup(), which cleans up the status
input device. Because the sysfs directory has already been removed,
this causes a WARNing.
- uvc_delete() calls media_device_unregister(), which cleans up the
media device. Because the sysfs directory has already been removed,
this causes another WARNing.
To fix this, we need to make sure the devices are always unregistered
before the end of uvc_disconnect(). To this, move the unregistration
into the disconnect path:
- split uvc_status_cleanup() into two parts, one on disconnect that
unregisters and one on delete that frees.
- move v4l2_device_unregister() and media_device_unregister() into
the disconnect path.
[0]: https://lkml.org/lkml/2016/12/8/657
[Renamed uvc_input_cleanup() to uvc_input_unregister()]
Signed-off-by: Daniel Axtens <dja@...ens.net>
Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++----
drivers/media/usb/uvc/uvc_status.c | 12 ++++++++----
drivers/media/usb/uvc/uvcvideo.h | 1 +
3 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index bc369a0934a3..76dc3ee8ca21 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1824,11 +1824,7 @@ static void uvc_delete(struct kref *kref)
usb_put_intf(dev->intf);
usb_put_dev(dev->udev);
- if (dev->vdev.dev)
- v4l2_device_unregister(&dev->vdev);
#ifdef CONFIG_MEDIA_CONTROLLER
- if (media_devnode_is_registered(dev->mdev.devnode))
- media_device_unregister(&dev->mdev);
media_device_cleanup(&dev->mdev);
#endif
@@ -1885,6 +1881,15 @@ static void uvc_unregister_video(struct uvc_device *dev)
uvc_debugfs_cleanup_stream(stream);
}
+
+ uvc_status_unregister(dev);
+
+ if (dev->vdev.dev)
+ v4l2_device_unregister(&dev->vdev);
+#ifdef CONFIG_MEDIA_CONTROLLER
+ if (media_devnode_is_registered(dev->mdev.devnode))
+ media_device_unregister(&dev->mdev);
+#endif
}
int uvc_register_video_device(struct uvc_device *dev,
diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c
index 0722dc684378..883e4cab45e7 100644
--- a/drivers/media/usb/uvc/uvc_status.c
+++ b/drivers/media/usb/uvc/uvc_status.c
@@ -54,7 +54,7 @@ error:
return ret;
}
-static void uvc_input_cleanup(struct uvc_device *dev)
+static void uvc_input_unregister(struct uvc_device *dev)
{
if (dev->input)
input_unregister_device(dev->input);
@@ -71,7 +71,7 @@ static void uvc_input_report_key(struct uvc_device *dev, unsigned int code,
#else
#define uvc_input_init(dev)
-#define uvc_input_cleanup(dev)
+#define uvc_input_unregister(dev)
#define uvc_input_report_key(dev, code, value)
#endif /* CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV */
@@ -292,12 +292,16 @@ int uvc_status_init(struct uvc_device *dev)
return 0;
}
-void uvc_status_cleanup(struct uvc_device *dev)
+void uvc_status_unregister(struct uvc_device *dev)
{
usb_kill_urb(dev->int_urb);
+ uvc_input_unregister(dev);
+}
+
+void uvc_status_cleanup(struct uvc_device *dev)
+{
usb_free_urb(dev->int_urb);
kfree(dev->status);
- uvc_input_cleanup(dev);
}
int uvc_status_start(struct uvc_device *dev, gfp_t flags)
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index c0cbd833d0a4..1db6634b2455 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -757,6 +757,7 @@ int uvc_register_video_device(struct uvc_device *dev,
/* Status */
int uvc_status_init(struct uvc_device *dev);
+void uvc_status_unregister(struct uvc_device *dev);
void uvc_status_cleanup(struct uvc_device *dev);
int uvc_status_start(struct uvc_device *dev, gfp_t flags);
void uvc_status_stop(struct uvc_device *dev);
--
2.19.1
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