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From: Tejun Heo <tj@kernel.org>
Newsgroups: gmane.linux.kernel,gmane.linux.usb.general
Subject: [PATCH driver-core-linus] kernfs: make kernfs_deactivate() honor
KERNFS_LOCKDEP flag
Date: Wed, 29 Jan 2014 12:04:03 -0500
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Cc: Denis Kirjanov <kda@linux-powerpc.org>,
linux-kernel@vger.kernel.org, USB list <linux-usb@vger.kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Fabio Estevam <festevam@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>
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Xref: news.gmane.org gmane.linux.kernel:1637396 gmane.linux.usb.general:102347
Archived-At: <http://permalink.gmane.org/gmane.linux.kernel/1637396>
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:
[<ffffffff81cfb6bd>] dump_stack+0x4e/0x7a
[<ffffffff810f8530>] __lock_acquire+0x1910/0x1e70
[<ffffffff810f931a>] lock_acquire+0x9a/0x1d0
[<ffffffff8127c75e>] kernfs_deactivate+0xee/0x130
[<ffffffff8127d4c8>] kernfs_addrm_finish+0x38/0x60
[<ffffffff8127d701>] kernfs_remove_by_name_ns+0x51/0xa0
[<ffffffff8127b4f1>] remove_files.isra.1+0x41/0x80
[<ffffffff8127b7e7>] sysfs_remove_group+0x47/0xa0
[<ffffffff8127b873>] sysfs_remove_groups+0x33/0x50
[<ffffffff8177d66d>] device_remove_attrs+0x4d/0x80
[<ffffffff8177e25e>] device_del+0x12e/0x1d0
[<ffffffff819722c2>] usb_disconnect+0x122/0x1a0
[<ffffffff819749b5>] hub_thread+0x3c5/0x1290
[<ffffffff810c6a6d>] kthread+0xed/0x110
[<ffffffff81d0a56c>] 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 <tj@kernel.org>
Reported-by: Fabio Estevam <festevam@gmail.com>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
---
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 5104cf5..bd6e18b 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_);
+ }
}
/**