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Commit 8b8f319f authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
Browse files

[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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f2eace23

kernel/futex.c

+18 −10
Original line number Diff line number Diff line
@@ -606,6 +606,22 @@ static int unlock_futex_pi(u32 __user *uaddr, u32 uval) 
	return 0;

}



/*

 * 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;