[tip PATCH v7 7/9] RFC: futex: Add requeue_futex() call

Darren Hart
2009-04-03T20:42:58Z

futex_requeue() is getting a bit long-winded, and will be getting more so after
the requeue_pi patch. Factor out the actual requeueing into a nicely contained
inline function to reduce function length and improve legibility.

Changelog:
V6: -Initial version

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sripathi Kodi <sripathik@in.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Dinakar Guniguntala <dino@in.ibm.com>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jakub Jelinek <jakub@redhat.com>
---

kernel/futex.c | 43 +++++++++++++++++++++++++++++--------------
1 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 04e5431..4fa5de1 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -940,6 +940,34 @@ out:
return ret;
}

+/**
+ * requeue_futex() - Requeue a futex_q from one hb to another
+ * @q: the futex_q to requeue
+ * @hb1: the source hash_bucket
+ * @hb2: the target hash_bucket
+ * @key2: the new key for the requeued futex_q
+ */
+static inline
+void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
+ struct futex_hash_bucket *hb2, union futex_key *key2)
+{
+
+ /*
+ * If key1 and key2 hash to the same bucket, no need to
+ * requeue.
+ */
+ if (likely(&hb1->chain != &hb2->chain)) {
+ plist_del(&q->list, &hb1->chain);
+ plist_add(&q->list, &hb2->chain);
+ q->lock_ptr = &hb2->lock;
+#ifdef CONFIG_DEBUG_PI_LIST
+ q->list.plist.lock = &hb2->lock;
+#endif
+ }
+ get_futex_key_refs(key2);
+ q->key = *key2;
+}
+
/*
* Requeue all waiters hashed on one physical page to another
* physical page.
@@ -999,20 +1027,7 @@ retry_private:
if (++ret <= nr_wake) {
wake_futex(this);
} else {
- /*
- * If key1 and key2 hash to the same bucket, no need to
- * requeue.
- */
- if (likely(head1 != &hb2->chain)) {
- plist_del(&this->list, &hb1->chain);
- plist_add(&this->list, &hb2->chain);
- this->lock_ptr = &hb2->lock;
-#ifdef CONFIG_DEBUG_PI_LIST
- this->list.plist.lock = &hb2->lock;
-#endif
- }
- this->key = key2;
- get_futex_key_refs(&key2);
+ requeue_futex(this, hb1, hb2, &key2);
drop_count++;

if (ret - nr_wake >= nr_requeue)