From da9846ae15186d491d6e21ebbb5051e1d3c7f652 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 29 Jan 2014 12:04:03 -0500 Subject: [PATCH] kernfs: make kernfs_deactivate() honor KERNFS_LOCKDEP flag kernfs_deactivate() forgot to check whether KERNFS_LOCKDEP is set before performing lockdep annotations and ends up feeding uninitialized lockdep_map to lockdep triggering warning like the following on USB stick hotunplug. usb 1-2: USB disconnect, device number 2 INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 1 PID: 62 Comm: khubd Not tainted 3.13.0-work+ #82 Hardware name: empty empty/S3992, BIOS 080011 10/26/2007 ffff880065ca7f60 ffff88013a4ffa08 ffffffff81cfb6bd 0000000000000002 ffff88013a4ffac8 ffffffff810f8530 ffff88013a4fc710 0000000000000002 ffff880100000000 ffffffff82a3db50 0000000000000001 ffff88013a4fc710 Call Trace: [] dump_stack+0x4e/0x7a [] __lock_acquire+0x1910/0x1e70 [] lock_acquire+0x9a/0x1d0 [] kernfs_deactivate+0xee/0x130 [] kernfs_addrm_finish+0x38/0x60 [] kernfs_remove_by_name_ns+0x51/0xa0 [] remove_files.isra.1+0x41/0x80 [] sysfs_remove_group+0x47/0xa0 [] sysfs_remove_groups+0x33/0x50 [] device_remove_attrs+0x4d/0x80 [] device_del+0x12e/0x1d0 [] usb_disconnect+0x122/0x1a0 [] hub_thread+0x3c5/0x1290 [] kthread+0xed/0x110 [] ret_from_fork+0x7c/0xb0 Fix it by making kernfs_deactivate() perform lockdep annotations only if KERNFS_LOCKDEP is set. Signed-off-by: Tejun Heo Reported-by: Fabio Estevam Reported-by: Alan Stern Reported-by: Jiri Kosina Reported-by: Dave Jones Tested-by: Fabio Estevam Tested-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- fs/kernfs/dir.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 5104cf5d25c5..bd6e18be6e1a 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -187,19 +187,23 @@ static void kernfs_deactivate(struct kernfs_node *kn) kn->u.completion = (void *)&wait; - rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) + rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); /* atomic_add_return() is a mb(), put_active() will always see * the updated kn->u.completion. */ v = atomic_add_return(KN_DEACTIVATED_BIAS, &kn->active); if (v != KN_DEACTIVATED_BIAS) { - lock_contended(&kn->dep_map, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) + lock_contended(&kn->dep_map, _RET_IP_); wait_for_completion(&wait); } - lock_acquired(&kn->dep_map, _RET_IP_); - rwsem_release(&kn->dep_map, 1, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) { + lock_acquired(&kn->dep_map, _RET_IP_); + rwsem_release(&kn->dep_map, 1, _RET_IP_); + } } /** -- 2.30.2