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authorFernando Luis Vázquez Cao <fernando_b1@lab.ntt.co.jp>2014-02-26 11:51:24 +0400
committerJiri Kosina <jkosina@suse.cz>2014-02-26 14:01:28 +0400
commit47587fc098451c2100dc1fb618855fc2e2d937af (patch)
tree229cc6c8a11f97b1b369c8faa554f91a5c054818
parent5f5750d2e471866576225c3af28eedfadebb0765 (diff)
downloadlinux-47587fc098451c2100dc1fb618855fc2e2d937af.tar.xz
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: [<ffffffff814cd684>] ? dump_stack+0x41/0x51 [<ffffffff810616e7>] ? warn_slowpath_common+0x77/0x90 [<ffffffff8106174c>] ? warn_slowpath_fmt+0x4c/0x50 [<ffffffff81374fd0>] ? device_del+0x40/0x1b0 [<ffffffff8137516f>] ? device_unregister+0x2f/0x50 [<ffffffff813751fa>] ? device_destroy+0x3a/0x40 [<ffffffffa03ca245>] ? drop_ref+0x55/0x120 [hid] [<ffffffffa03ca3e6>] ? hidraw_release+0x96/0xb0 [hid] [<ffffffff811929da>] ? __fput+0xca/0x210 [<ffffffff8107fe17>] ? task_work_run+0x97/0xd0 [<ffffffff810139a9>] ? do_notify_resume+0x69/0xa0 [<ffffffff814dbd22>] ? 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 <fernando@oss.ntt.co.jp> Reviewed-by: David Herrmann <dh.herrmann@gmail.com> Cc: stable@vger.kernel.org # 3.13 Signed-off-by: Jiri Kosina <jkosina@suse.cz>
-rw-r--r--drivers/hid/hidraw.c4
1 files 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 {