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| author | Ingo Molnar <mingo@elte.hu> | 2006-07-03 00:25:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-07-03 15:27:06 -0700 |
| commit | 8b8f319fc7f4ab59f567d6a401a62659b3d37007 (patch) | |
| tree | f483c5447619de848e2357ba157a1e09277b5c93 /kernel/futex.c | |
| parent | f2eace23e924bd3f05aedea4fc505eb5508d2d93 (diff) | |
| download | lwn-8b8f319fc7f4ab59f567d6a401a62659b3d37007.tar.gz lwn-8b8f319fc7f4ab59f567d6a401a62659b3d37007.zip | |
[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/futex.c')
| -rw-r--r-- | kernel/futex.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 15caf93e4a43..1dc98e4dd287 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; |