Ming Lei ba18311dff HID: usbhid: fix dead lock between open and disconect ... There is no reason to hold hiddev->existancelock before calling usb_deregister_dev, so move it out of the lock. The patch fixes the lockdep warning below. [ 5733.386271] ====================================================== [ 5733.386274] [ INFO: possible circular locking dependency detected ] [ 5733.386278] 3.2.0-custom-next-20120111+ #1 Not tainted [ 5733.386281] ------------------------------------------------------- [ 5733.386284] khubd/186 is trying to acquire lock: [ 5733.386288] (minor_rwsem){++++.+}, at: [<ffffffffa0011a04>] usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386311] [ 5733.386312] but task is already holding lock: [ 5733.386315] (&hiddev->existancelock){+.+...}, at: [<ffffffffa0094d17>] hiddev_disconnect+0x26/0x87 [usbhid] [ 5733.386328] [ 5733.386329] which lock already depends on the new lock. [ 5733.386330] [ 5733.386333] [ 5733.386334] the existing dependency chain (in reverse order) is: [ 5733.386336] [ 5733.386337] -> #1 (&hiddev->existancelock){+.+...}: [ 5733.386346] [<ffffffff81082d26>] lock_acquire+0xcb/0x10e [ 5733.386357] [<ffffffff813df961>] __mutex_lock_common+0x60/0x465 [ 5733.386366] [<ffffffff813dfe4d>] mutex_lock_nested+0x36/0x3b [ 5733.386371] [<ffffffffa0094ad6>] hiddev_open+0x113/0x193 [usbhid] [ 5733.386378] [<ffffffffa0011971>] usb_open+0x66/0xc2 [usbcore] [ 5733.386390] [<ffffffff8111a8b5>] chrdev_open+0x12b/0x154 [ 5733.386402] [<ffffffff811159a8>] __dentry_open.isra.16+0x20b/0x355 [ 5733.386408] [<ffffffff811165dc>] nameidata_to_filp+0x43/0x4a [ 5733.386413] [<ffffffff81122ed5>] do_last+0x536/0x570 [ 5733.386419] [<ffffffff8112300b>] path_openat+0xce/0x301 [ 5733.386423] [<ffffffff81123327>] do_filp_open+0x33/0x81 [ 5733.386427] [<ffffffff8111664d>] do_sys_open+0x6a/0xfc [ 5733.386431] [<ffffffff811166fb>] sys_open+0x1c/0x1e [ 5733.386434] [<ffffffff813e7c79>] system_call_fastpath+0x16/0x1b [ 5733.386441] [ 5733.386441] -> #0 (minor_rwsem){++++.+}: [ 5733.386448] [<ffffffff8108255d>] __lock_acquire+0xa80/0xd74 [ 5733.386454] [<ffffffff81082d26>] lock_acquire+0xcb/0x10e [ 5733.386458] [<ffffffff813e01f5>] down_write+0x44/0x77 [ 5733.386464] [<ffffffffa0011a04>] usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386475] [<ffffffffa0094d2d>] hiddev_disconnect+0x3c/0x87 [usbhid] [ 5733.386483] [<ffffffff8132df51>] hid_disconnect+0x3f/0x54 [ 5733.386491] [<ffffffff8132dfb4>] hid_device_remove+0x4e/0x7a [ 5733.386496] [<ffffffff812c0957>] __device_release_driver+0x81/0xcd [ 5733.386502] [<ffffffff812c09c3>] device_release_driver+0x20/0x2d [ 5733.386507] [<ffffffff812c0564>] bus_remove_device+0x114/0x128 [ 5733.386512] [<ffffffff812bdd6f>] device_del+0x131/0x183 [ 5733.386519] [<ffffffff8132def3>] hid_destroy_device+0x1e/0x3d [ 5733.386525] [<ffffffffa00916b0>] usbhid_disconnect+0x36/0x42 [usbhid] [ 5733.386530] [<ffffffffa000fb60>] usb_unbind_interface+0x57/0x11f [usbcore] [ 5733.386542] [<ffffffff812c0957>] __device_release_driver+0x81/0xcd [ 5733.386547] [<ffffffff812c09c3>] device_release_driver+0x20/0x2d [ 5733.386552] [<ffffffff812c0564>] bus_remove_device+0x114/0x128 [ 5733.386557] [<ffffffff812bdd6f>] device_del+0x131/0x183 [ 5733.386562] [<ffffffffa000de61>] usb_disable_device+0xa8/0x1d8 [usbcore] [ 5733.386573] [<ffffffffa0006bd2>] usb_disconnect+0xab/0x11f [usbcore] [ 5733.386583] [<ffffffffa0008aa0>] hub_thread+0x73b/0x1157 [usbcore] [ 5733.386593] [<ffffffff8105dc0f>] kthread+0x95/0x9d [ 5733.386601] [<ffffffff813e90b4>] kernel_thread_helper+0x4/0x10 [ 5733.386607] [ 5733.386608] other info that might help us debug this: [ 5733.386609] [ 5733.386612] Possible unsafe locking scenario: [ 5733.386613] [ 5733.386615] CPU0 CPU1 [ 5733.386618] ---- ---- [ 5733.386620] lock(&hiddev->existancelock); [ 5733.386625] lock(minor_rwsem); [ 5733.386630] lock(&hiddev->existancelock); [ 5733.386635] lock(minor_rwsem); [ 5733.386639] [ 5733.386640] *** DEADLOCK *** [ 5733.386641] [ 5733.386644] 6 locks held by khubd/186: [ 5733.386646] #0: (&__lockdep_no_validate__){......}, at: [<ffffffffa00084af>] hub_thread+0x14a/0x1157 [usbcore] [ 5733.386661] #1: (&__lockdep_no_validate__){......}, at: [<ffffffffa0006b77>] usb_disconnect+0x50/0x11f [usbcore] [ 5733.386677] #2: (hcd->bandwidth_mutex){+.+.+.}, at: [<ffffffffa0006bc8>] usb_disconnect+0xa1/0x11f [usbcore] [ 5733.386693] #3: (&__lockdep_no_validate__){......}, at: [<ffffffff812c09bb>] device_release_driver+0x18/0x2d [ 5733.386704] #4: (&__lockdep_no_validate__){......}, at: [<ffffffff812c09bb>] device_release_driver+0x18/0x2d [ 5733.386714] #5: (&hiddev->existancelock){+.+...}, at: [<ffffffffa0094d17>] hiddev_disconnect+0x26/0x87 [usbhid] [ 5733.386727] [ 5733.386727] stack backtrace: [ 5733.386731] Pid: 186, comm: khubd Not tainted 3.2.0-custom-next-20120111+ #1 [ 5733.386734] Call Trace: [ 5733.386741] [<ffffffff81062881>] ? up+0x34/0x3b [ 5733.386747] [<ffffffff813d9ef3>] print_circular_bug+0x1f8/0x209 [ 5733.386752] [<ffffffff8108255d>] __lock_acquire+0xa80/0xd74 [ 5733.386756] [<ffffffff810808b4>] ? trace_hardirqs_on_caller+0x15d/0x1a3 [ 5733.386763] [<ffffffff81043a3f>] ? vprintk+0x3f4/0x419 [ 5733.386774] [<ffffffffa0011a04>] ? usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386779] [<ffffffff81082d26>] lock_acquire+0xcb/0x10e [ 5733.386789] [<ffffffffa0011a04>] ? usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386797] [<ffffffff813e01f5>] down_write+0x44/0x77 [ 5733.386807] [<ffffffffa0011a04>] ? usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386818] [<ffffffffa0011a04>] usb_deregister_dev+0x37/0x9e [usbcore] [ 5733.386825] [<ffffffffa0094d2d>] hiddev_disconnect+0x3c/0x87 [usbhid] [ 5733.386830] [<ffffffff8132df51>] hid_disconnect+0x3f/0x54 [ 5733.386834] [<ffffffff8132dfb4>] hid_device_remove+0x4e/0x7a [ 5733.386839] [<ffffffff812c0957>] __device_release_driver+0x81/0xcd [ 5733.386844] [<ffffffff812c09c3>] device_release_driver+0x20/0x2d [ 5733.386848] [<ffffffff812c0564>] bus_remove_device+0x114/0x128 [ 5733.386854] [<ffffffff812bdd6f>] device_del+0x131/0x183 [ 5733.386859] [<ffffffff8132def3>] hid_destroy_device+0x1e/0x3d [ 5733.386865] [<ffffffffa00916b0>] usbhid_disconnect+0x36/0x42 [usbhid] [ 5733.386876] [<ffffffffa000fb60>] usb_unbind_interface+0x57/0x11f [usbcore] [ 5733.386882] [<ffffffff812c0957>] __device_release_driver+0x81/0xcd [ 5733.386886] [<ffffffff812c09c3>] device_release_driver+0x20/0x2d [ 5733.386890] [<ffffffff812c0564>] bus_remove_device+0x114/0x128 [ 5733.386895] [<ffffffff812bdd6f>] device_del+0x131/0x183 [ 5733.386905] [<ffffffffa000de61>] usb_disable_device+0xa8/0x1d8 [usbcore] [ 5733.386916] [<ffffffffa0006bd2>] usb_disconnect+0xab/0x11f [usbcore] [ 5733.386921] [<ffffffff813dff82>] ? __mutex_unlock_slowpath+0x130/0x141 [ 5733.386929] [<ffffffffa0008aa0>] hub_thread+0x73b/0x1157 [usbcore] [ 5733.386935] [<ffffffff8106a51d>] ? finish_task_switch+0x78/0x150 [ 5733.386941] [<ffffffff8105e396>] ? __init_waitqueue_head+0x4c/0x4c [ 5733.386950] [<ffffffffa0008365>] ? usb_remote_wakeup+0x56/0x56 [usbcore] [ 5733.386955] [<ffffffff8105dc0f>] kthread+0x95/0x9d [ 5733.386961] [<ffffffff813e90b4>] kernel_thread_helper+0x4/0x10 [ 5733.386966] [<ffffffff813e24b8>] ? retint_restore_args+0x13/0x13 [ 5733.386970] [<ffffffff8105db7a>] ? __init_kthread_worker+0x55/0x55 [ 5733.386974] [<ffffffff813e90b0>] ? gs_change+0x13/0x13 Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>		2012-02-02 09:48:00 +01:00
..
hid-core.c	HID: usbhid: defer LED setting to a workqueue	2011-12-21 11:18:35 +01:00
hid-pidff.c	HID: Add and use hid_<level>: dev_<level> equivalents	2010-12-10 15:10:38 +01:00
hid-quirks.c	Merge branches 'hyperv', 'multitouch', 'roccat', 'upstream', 'upstream-fixes', 'wacom' and 'wiimote' into for-linus	2012-01-05 15:51:02 +01:00
hiddev.c	HID: usbhid: fix dead lock between open and disconect	2012-02-02 09:48:00 +01:00
Kconfig	kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT	2011-01-20 17:02:05 -08:00
Makefile	HID: usbhid: Clean up makefile (-y instead of -objs)	2010-11-18 10:43:18 +01:00
usbhid.h	HID: usbhid: defer LED setting to a workqueue	2011-12-21 11:18:35 +01:00
usbkbd.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid	2012-01-10 10:48:28 -08:00
usbmouse.c	USB: convert drivers/hid/* to use module_usb_driver()	2011-11-18 09:49:34 -08:00