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-rw-r--r--kernel/futex.c28
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 15caf93..1dc98e4 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;
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