aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorVegard Nossum <vegard.nossum@gmail.com>2008-08-31 17:39:21 -0400
committerThomas Gleixner <tglx@linutronix.de>2008-09-01 03:47:16 -0400
commit673d62cc5ea6fca046650f17f77985b112c62322 (patch)
tree7cde0d756ffa71ad732cc079d28254b256c14e68
parentbef69ea0dcce574a425feb0a5aa4c63dd108b9a6 (diff)
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>
-rw-r--r--include/linux/list.h13
-rw-r--r--lib/debugobjects.c31
2 files changed, 36 insertions, 8 deletions
diff --git a/include/linux/list.h b/include/linux/list.h
index db35ef02e745..969f6e92d089 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -619,6 +619,19 @@ static inline void hlist_add_after(struct hlist_node *n,
619 next->next->pprev = &next->next; 619 next->next->pprev = &next->next;
620} 620}
621 621
622/*
623 * Move a list from one list head to another. Fixup the pprev
624 * reference of the first entry if it exists.
625 */
626static inline void hlist_move_list(struct hlist_head *old,
627 struct hlist_head *new)
628{
629 new->first = old->first;
630 if (new->first)
631 new->first->pprev = &new->first;
632 old->first = NULL;
633}
634
622#define hlist_entry(ptr, type, member) container_of(ptr,type,member) 635#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
623 636
624#define hlist_for_each(pos, head) \ 637#define hlist_for_each(pos, head) \
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 45a6bde762d1..e3ab374e1334 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -112,6 +112,7 @@ static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b)
112 112
113/* 113/*
114 * Allocate a new object. If the pool is empty, switch off the debugger. 114 * Allocate a new object. If the pool is empty, switch off the debugger.
115 * Must be called with interrupts disabled.
115 */ 116 */
116static struct debug_obj * 117static struct debug_obj *
117alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) 118alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr)
@@ -148,17 +149,18 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr)
148static void free_object(struct debug_obj *obj) 149static void free_object(struct debug_obj *obj)
149{ 150{
150 unsigned long idx = (unsigned long)(obj - obj_static_pool); 151 unsigned long idx = (unsigned long)(obj - obj_static_pool);
152 unsigned long flags;
151 153
152 if (obj_pool_free < ODEBUG_POOL_SIZE || idx < ODEBUG_POOL_SIZE) { 154 if (obj_pool_free < ODEBUG_POOL_SIZE || idx < ODEBUG_POOL_SIZE) {
153 spin_lock(&pool_lock); 155 spin_lock_irqsave(&pool_lock, flags);
154 hlist_add_head(&obj->node, &obj_pool); 156 hlist_add_head(&obj->node, &obj_pool);
155 obj_pool_free++; 157 obj_pool_free++;
156 obj_pool_used--; 158 obj_pool_used--;
157 spin_unlock(&pool_lock); 159 spin_unlock_irqrestore(&pool_lock, flags);
158 } else { 160 } else {
159 spin_lock(&pool_lock); 161 spin_lock_irqsave(&pool_lock, flags);
160 obj_pool_used--; 162 obj_pool_used--;
161 spin_unlock(&pool_lock); 163 spin_unlock_irqrestore(&pool_lock, flags);
162 kmem_cache_free(obj_cache, obj); 164 kmem_cache_free(obj_cache, obj);
163 } 165 }
164} 166}
@@ -171,6 +173,7 @@ static void debug_objects_oom(void)
171{ 173{
172 struct debug_bucket *db = obj_hash; 174 struct debug_bucket *db = obj_hash;
173 struct hlist_node *node, *tmp; 175 struct hlist_node *node, *tmp;
176 HLIST_HEAD(freelist);
174 struct debug_obj *obj; 177 struct debug_obj *obj;
175 unsigned long flags; 178 unsigned long flags;
176 int i; 179 int i;
@@ -179,11 +182,14 @@ static void debug_objects_oom(void)
179 182
180 for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) { 183 for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
181 spin_lock_irqsave(&db->lock, flags); 184 spin_lock_irqsave(&db->lock, flags);
182 hlist_for_each_entry_safe(obj, node, tmp, &db->list, node) { 185 hlist_move_list(&db->list, &freelist);
186 spin_unlock_irqrestore(&db->lock, flags);
187
188 /* Now free them */
189 hlist_for_each_entry_safe(obj, node, tmp, &freelist, node) {
183 hlist_del(&obj->node); 190 hlist_del(&obj->node);
184 free_object(obj); 191 free_object(obj);
185 } 192 }
186 spin_unlock_irqrestore(&db->lock, flags);
187 } 193 }
188} 194}
189 195
@@ -498,8 +504,9 @@ void debug_object_free(void *addr, struct debug_obj_descr *descr)
498 return; 504 return;
499 default: 505 default:
500 hlist_del(&obj->node); 506 hlist_del(&obj->node);
507 spin_unlock_irqrestore(&db->lock, flags);
501 free_object(obj); 508 free_object(obj);
502 break; 509 return;
503 } 510 }
504out_unlock: 511out_unlock:
505 spin_unlock_irqrestore(&db->lock, flags); 512 spin_unlock_irqrestore(&db->lock, flags);
@@ -510,6 +517,7 @@ static void __debug_check_no_obj_freed(const void *address, unsigned long size)
510{ 517{
511 unsigned long flags, oaddr, saddr, eaddr, paddr, chunks; 518 unsigned long flags, oaddr, saddr, eaddr, paddr, chunks;
512 struct hlist_node *node, *tmp; 519 struct hlist_node *node, *tmp;
520 HLIST_HEAD(freelist);
513 struct debug_obj_descr *descr; 521 struct debug_obj_descr *descr;
514 enum debug_obj_state state; 522 enum debug_obj_state state;
515 struct debug_bucket *db; 523 struct debug_bucket *db;
@@ -545,11 +553,18 @@ repeat:
545 goto repeat; 553 goto repeat;
546 default: 554 default:
547 hlist_del(&obj->node); 555 hlist_del(&obj->node);
548 free_object(obj); 556 hlist_add_head(&obj->node, &freelist);
549 break; 557 break;
550 } 558 }
551 } 559 }
552 spin_unlock_irqrestore(&db->lock, flags); 560 spin_unlock_irqrestore(&db->lock, flags);
561
562 /* Now free them */
563 hlist_for_each_entry_safe(obj, node, tmp, &freelist, node) {
564 hlist_del(&obj->node);
565 free_object(obj);
566 }
567
553 if (cnt > debug_objects_maxchain) 568 if (cnt > debug_objects_maxchain)
554 debug_objects_maxchain = cnt; 569 debug_objects_maxchain = cnt;
555 } 570 }