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authorDarren Hart <dvhltc@us.ibm.com>2009-09-22 01:30:15 -0400
committerIngo Molnar <mingo@elte.hu>2009-09-22 04:37:43 -0400
commitd40d65c8dbdd39f0b64e043f6bd08f8a38f55194 (patch)
tree382d9870943ea689bfb547c5071fd4b95182b29c /kernel/futex.c
parent56ec1607b15b6a5f6de5aab14f16a763b88296fc (diff)
futex: Correct queue_me and unqueue_me commentary
The queue_me/unqueue_me commentary is oddly placed and out of date. Clean it up and correct the inaccurate bits. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20090922053015.8717.71713.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/futex.c')
-rw-r--r--kernel/futex.c41
1 files changed, 29 insertions, 12 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 6c498b145a4f..cedcd60f26ff 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1350,6 +1350,25 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
1350 return hb; 1350 return hb;
1351} 1351}
1352 1352
1353static inline void
1354queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
1355{
1356 spin_unlock(&hb->lock);
1357 drop_futex_key_refs(&q->key);
1358}
1359
1360/**
1361 * queue_me() - Enqueue the futex_q on the futex_hash_bucket
1362 * @q: The futex_q to enqueue
1363 * @hb: The destination hash bucket
1364 *
1365 * The hb->lock must be held by the caller, and is released here. A call to
1366 * queue_me() is typically paired with exactly one call to unqueue_me(). The
1367 * exceptions involve the PI related operations, which may use unqueue_me_pi()
1368 * or nothing if the unqueue is done as part of the wake process and the unqueue
1369 * state is implicit in the state of woken task (see futex_wait_requeue_pi() for
1370 * an example).
1371 */
1353static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) 1372static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
1354{ 1373{
1355 int prio; 1374 int prio;
@@ -1373,19 +1392,17 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
1373 spin_unlock(&hb->lock); 1392 spin_unlock(&hb->lock);
1374} 1393}
1375 1394
1376static inline void 1395/**
1377queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) 1396 * unqueue_me() - Remove the futex_q from its futex_hash_bucket
1378{ 1397 * @q: The futex_q to unqueue
1379 spin_unlock(&hb->lock); 1398 *
1380 drop_futex_key_refs(&q->key); 1399 * The q->lock_ptr must not be held by the caller. A call to unqueue_me() must
1381} 1400 * be paired with exactly one earlier call to queue_me().
1382 1401 *
1383/* 1402 * Returns:
1384 * queue_me and unqueue_me must be called as a pair, each 1403 * 1 - if the futex_q was still queued (and we removed unqueued it)
1385 * exactly once. They are called with the hashed spinlock held. 1404 * 0 - if the futex_q was already removed by the waking thread
1386 */ 1405 */
1387
1388/* Return 1 if we were still queued (ie. 0 means we were woken) */
1389static int unqueue_me(struct futex_q *q) 1406static int unqueue_me(struct futex_q *q)
1390{ 1407{
1391 spinlock_t *lock_ptr; 1408 spinlock_t *lock_ptr;