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>
diff --git a/include/linux/list.h b/include/linux/list.h
index db35ef0..969f6e9 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -619,6 +619,19 @@
next->next->pprev = &next->next;
}
+/*
+ * Move a list from one list head to another. Fixup the pprev
+ * reference of the first entry if it exists.
+ */
+static inline void hlist_move_list(struct hlist_head *old,
+ struct hlist_head *new)
+{
+ new->first = old->first;
+ if (new->first)
+ new->first->pprev = &new->first;
+ old->first = NULL;
+}
+
#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
#define hlist_for_each(pos, head) \