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authorDarren Hart <dvhltc@us.ibm.com>2009-03-12 00:55:52 -0700
committerIngo Molnar <mingo@elte.hu>2009-03-12 11:20:56 +0100
commit5eb3dc62fc5986e85715041c23dcf3832812be4b (patch)
treee8b55b84cc50841ab7f7c87afdcc3d5e419cb4e9 /kernel
parentde87fcc124a5d4a171aa32707b3265608ebda6e7 (diff)
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futex: add double_unlock_hb()
Impact: cleanup The futex code uses double_lock_hb() which locks the hb->lock's in pointer value order. There is no parallel unlock routine, and the code unlocks them in name order, ignoring pointer value. This patch adds double_unlock_hb() to refactor the duplicated code segments. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075552.9856.48021.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/futex.c29
1 files changed, 17 insertions, 12 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 4000454e4d8..e149545c5ce 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -690,6 +690,19 @@ double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
}
}
+static inline void
+double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
+{
+ if (hb1 <= hb2) {
+ spin_unlock(&hb2->lock);
+ if (hb1 < hb2)
+ spin_unlock(&hb1->lock);
+ } else { /* hb1 > hb2 */
+ spin_unlock(&hb1->lock);
+ spin_unlock(&hb2->lock);
+ }
+}
+
/*
* Wake up waiters matching bitset queued on this futex (uaddr).
*/
@@ -767,9 +780,7 @@ retry:
if (unlikely(op_ret < 0)) {
u32 dummy;
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ double_unlock_hb(hb1, hb2);
#ifndef CONFIG_MMU
/*
@@ -833,9 +844,7 @@ retry:
ret += op_ret;
}
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ double_unlock_hb(hb1, hb2);
out_put_keys:
put_futex_key(fshared, &key2);
out_put_key1:
@@ -876,9 +885,7 @@ retry:
ret = get_futex_value_locked(&curval, uaddr1);
if (unlikely(ret)) {
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ double_unlock_hb(hb1, hb2);
put_futex_key(fshared, &key2);
put_futex_key(fshared, &key1);
@@ -925,9 +932,7 @@ retry:
}
out_unlock:
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ double_unlock_hb(hb1, hb2);
/* drop_futex_key_refs() must be called outside the spinlocks. */
while (--drop_count >= 0)