From 2228d80dd05a4fc5a410fde847677b8fb3eb23d7 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 24 Oct 2014 05:10:20 -0300 Subject: [PATCH] [media] uvcvideo: Fix destruction order in uvc_delete() We've got a bug report at disconnecting a Webcam, where the kernel spews warnings like below: WARNING: CPU: 0 PID: 8385 at ../fs/sysfs/group.c:219 sysfs_remove_group+0x87/0x90() sysfs group c0b2350c not found for kobject 'event3' CPU: 0 PID: 8385 Comm: queue2:src Not tainted 3.16.2-1.gdcee397-default #1 Hardware name: ASUSTeK Computer INC. A7N8X-E/A7N8X-E, BIOS ASUS A7N8X-E Deluxe ACPI BIOS Rev 1013 11/12/2004 c08d0705 ddc75cbc c0718c5b ddc75ccc c024b654 c08c6d44 ddc75ce8 000020c1 c08d0705 000000db c03d1ec7 c03d1ec7 00000009 00000000 c0b2350c d62c9064 ddc75cd4 c024b6a3 00000009 ddc75ccc c08c6d44 ddc75ce8 ddc75cfc c03d1ec7 Call Trace: [] try_stack_unwind+0x156/0x170 [] dump_trace+0x53/0x180 [] show_trace_log_lvl+0x46/0x50 [] show_stack_log_lvl+0x51/0xe0 [] show_stack+0x27/0x50 [] dump_stack+0x3e/0x4e [] warn_slowpath_common+0x84/0xa0 [] warn_slowpath_fmt+0x33/0x40 [] sysfs_remove_group+0x87/0x90 [] device_del+0x34/0x180 [] evdev_disconnect+0x19/0x50 [] __input_unregister_device+0x9a/0x140 [] input_unregister_device+0x45/0x80 [] uvc_delete+0x26/0x110 [uvcvideo] [] v4l2_device_release+0x98/0xc0 [videodev] [] device_release+0x2b/0x90 [] kobject_cleanup+0x6f/0x1a0 [] v4l2_release+0x43/0x70 [videodev] [] __fput+0xb1/0x1b0 [] task_work_run+0x91/0xb0 [] do_exit+0x265/0x910 [] do_group_exit+0x34/0xa0 [] get_signal_to_deliver+0x17f/0x590 [] do_signal+0x3a/0x960 [] do_notify_resume+0x67/0x90 [] work_notifysig+0x30/0x3b [] 0xb7739e5f ---[ end trace b1e56095a485b631 ]--- The cause is that uvc_status_cleanup() is called after usb_put_*() in uvc_delete(). usb_put_*() removes the sysfs parent and eventually removes the children recursively, so the later device_del() can't find its sysfs. The fix is simply rearrange the call orders in uvc_delete() so that the child is removed before the parent. Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=897736 Reported-and-tested-by: Martin Pluskal Cc: Signed-off-by: Takashi Iwai Signed-off-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- drivers/media/usb/uvc/uvc_driver.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index b7e111df5c3c..a327f3d09420 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1639,12 +1639,12 @@ static void uvc_delete(struct uvc_device *dev) { struct list_head *p, *n; - usb_put_intf(dev->intf); - usb_put_dev(dev->udev); - uvc_status_cleanup(dev); uvc_ctrl_cleanup_device(dev); + usb_put_intf(dev->intf); + usb_put_dev(dev->udev); + if (dev->vdev.dev) v4l2_device_unregister(&dev->vdev); #ifdef CONFIG_MEDIA_CONTROLLER