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authorIngo Molnar <mingo@elte.hu>2006-07-03 00:25:05 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-03 15:27:06 -0700
commit8b8f319fc7f4ab59f567d6a401a62659b3d37007 (patch)
treef483c5447619de848e2357ba157a1e09277b5c93 /kernel
parentf2eace23e924bd3f05aedea4fc505eb5508d2d93 (diff)
[PATCH] lockdep: annotate futex
Teach special (recursive) locking code to the lock validator. Introduces double_lock_hb() to unify double- hash-bucket-lock taking. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/futex.c28
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 15caf93e4a4..1dc98e4dd28 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -607,6 +607,22 @@ static int unlock_futex_pi(u32 __user *uaddr, u32 uval)
}
/*
+ * Express the locking dependencies for lockdep:
+ */
+static inline void
+double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
+{
+ if (hb1 <= hb2) {
+ spin_lock(&hb1->lock);
+ if (hb1 < hb2)
+ spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING);
+ } else { /* hb1 > hb2 */
+ spin_lock(&hb2->lock);
+ spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING);
+ }
+}
+
+/*
* Wake up all waiters hashed on the physical page that is mapped
* to this virtual address:
*/
@@ -674,11 +690,7 @@ retryfull:
hb2 = hash_futex(&key2);
retry:
- if (hb1 < hb2)
- spin_lock(&hb1->lock);
- spin_lock(&hb2->lock);
- if (hb1 > hb2)
- spin_lock(&hb1->lock);
+ double_lock_hb(hb1, hb2);
op_ret = futex_atomic_op_inuser(op, uaddr2);
if (unlikely(op_ret < 0)) {
@@ -787,11 +799,7 @@ static int futex_requeue(u32 __user *uaddr1, u32 __user *uaddr2,
hb1 = hash_futex(&key1);
hb2 = hash_futex(&key2);
- if (hb1 < hb2)
- spin_lock(&hb1->lock);
- spin_lock(&hb2->lock);
- if (hb1 > hb2)
- spin_lock(&hb1->lock);
+ double_lock_hb(hb1, hb2);
if (likely(cmpval != NULL)) {
u32 curval;