debugobjects: fix lockdep warning
authorVegard Nossum <vegard.nossum@gmail.com>
Sun, 31 Aug 2008 21:39:21 +0000 (23:39 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Mon, 1 Sep 2008 07:47:16 +0000 (09:47 +0200)
commit673d62cc5ea6fca046650f17f77985b112c62322
tree7cde0d756ffa71ad732cc079d28254b256c14e68
parentbef69ea0dcce574a425feb0a5aa4c63dd108b9a6
debugobjects: fix lockdep warning

Daniel J. Blueman reported:
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.27-rc4-224c #1
> -------------------------------------------------------
> hald/4680 is trying to acquire lock:
>  (&n->list_lock){++..}, at: [<ffffffff802bfa26>] add_partial+0x26/0x80
>
> but task is already holding lock:
>  (&obj_hash[i].lock){++..}, at: [<ffffffff8041cfdc>]
> debug_object_free+0x5c/0x120

We fix it by moving the actual freeing to outside the lock (the lock
now only protects the list).

The pool lock is also promoted to irq-safe (suggested by Dan). It's
necessary because free_pool is now called outside the irq disabled
region. So we need to protect against an interrupt handler which calls
debug_object_init().

[tglx@linutronix.de: added hlist_move_list helper to avoid looping
     through the list twice]

Reported-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
include/linux/list.h
lib/debugobjects.c