Gitweb: http://git.kernel.org/linus/5eb3dc62fc5986e85715041c23dcf3832812be4b
Commit: 5eb3dc62fc5986e85715041c23dcf3832812be4b
Parent: de87fcc124a5d4a171aa32707b3265608ebda6e7
Author: Darren Hart <dvhltc@us.ibm.com>
AuthorDate: Thu Mar 12 00:55:52 2009 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu Mar 12 11:20:56 2009 +0100
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>
---
kernel/futex.c | 29 +++++++++++++++++------------
1 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 4000454..e149545 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)
--
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