From 47587fc098451c2100dc1fb618855fc2e2d937af Mon Sep 17 00:00:00 2001 From: =?utf8?q?Fernando=20Luis=20V=C3=A1zquez=20Cao?= Date: Wed, 26 Feb 2014 16:51:24 +0900 Subject: [PATCH] HID: hidraw: fix warning destroying hidraw device files after parent I noticed that after hot unplugging a Logitech unifying receiver (drivers/hid/hid-logitech-dj.c) the kernel would occasionally spew a stack trace similar to this: usb 1-1.1.2: USB disconnect, device number 7 WARNING: CPU: 0 PID: 2865 at fs/sysfs/group.c:216 device_del+0x40/0x1b0() sysfs group ffffffff8187fa20 not found for kobject 'hidraw0' [...] CPU: 0 PID: 2865 Comm: upowerd Tainted: G W 3.14.0-rc4 #7 Hardware name: LENOVO 7783PN4/ , BIOS 9HKT43AUS 07/11/2011 0000000000000009 ffffffff814cd684 ffff880427ccfdf8 ffffffff810616e7 ffff88041ec61800 ffff880427ccfe48 ffff88041e444d80 ffff880426fab8e8 ffff880429359960 ffffffff8106174c ffffffff81714b98 0000000000000028 Call Trace: [] ? dump_stack+0x41/0x51 [] ? warn_slowpath_common+0x77/0x90 [] ? warn_slowpath_fmt+0x4c/0x50 [] ? device_del+0x40/0x1b0 [] ? device_unregister+0x2f/0x50 [] ? device_destroy+0x3a/0x40 [] ? drop_ref+0x55/0x120 [hid] [] ? hidraw_release+0x96/0xb0 [hid] [] ? __fput+0xca/0x210 [] ? task_work_run+0x97/0xd0 [] ? do_notify_resume+0x69/0xa0 [] ? int_signal+0x12/0x17 ---[ end trace 63f4a46f6566d737 ]--- During device removal hid_disconnect() is called via hid_hw_stop() to stop the device and free all its resources, including the sysfs files. The problem is that if a user space process, such as upowerd, holds a reference to a hidraw file the corresponding sysfs files will be kept around (drop_ref() does not call device_destroy() if the open counter is not 0) and it will be usb_disconnect() who, by calling device_del() for the USB device, will indirectly remove the sysfs files of the hidraw device (sysfs_remove_dir() is recursive these days). Because of this, by the time user space releases the last reference to the hidraw file and drop_ref() tries to destroy the device the sysfs files are already gone and the kernel will print the warning above. Fix this by calling device_destroy() at USB disconnect time. Signed-off-by: Fernando Luis Vazquez Cao Reviewed-by: David Herrmann Cc: stable@vger.kernel.org # 3.13 Signed-off-by: Jiri Kosina --- drivers/hid/hidraw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c index cb0137b3718d..ab24ce2eb28f 100644 --- a/drivers/hid/hidraw.c +++ b/drivers/hid/hidraw.c @@ -320,13 +320,13 @@ static void drop_ref(struct hidraw *hidraw, int exists_bit) hid_hw_close(hidraw->hid); wake_up_interruptible(&hidraw->wait); } + device_destroy(hidraw_class, + MKDEV(hidraw_major, hidraw->minor)); } else { --hidraw->open; } if (!hidraw->open) { if (!hidraw->exist) { - device_destroy(hidraw_class, - MKDEV(hidraw_major, hidraw->minor)); hidraw_table[hidraw->minor] = NULL; kfree(hidraw); } else { -- 2.20.1