futex: make the vectored futex operations available

Rename unqueue_multiple() as futex_unqueue_multiple(), and make both
that and futex_wait_multiple_setup() available for external users. This
is in preparation for wiring up vectored waits in io_uring.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

kernel/futex/futex.h

@@ -366,6 +366,11 @@ extern int futex_parse_waitv(struct futex_vector *futexv,
 			     unsigned int nr_futexes, futex_wake_fn *wake,
 			     void *wake_data);
 
+extern int futex_wait_multiple_setup(struct futex_vector *vs, int count,
+				     int *woken);
+
+extern int futex_unqueue_multiple(struct futex_vector *v, int count);
+
 extern int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
 			       struct hrtimer_sleeper *to);
 

kernel/futex/waitwake.c

@@ -372,7 +372,7 @@ void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q,
 }
 
 /**
- * unqueue_multiple - Remove various futexes from their hash bucket
+ * futex_unqueue_multiple - Remove various futexes from their hash bucket
  * @v:	   The list of futexes to unqueue
  * @count: Number of futexes in the list
  *
@@ -382,7 +382,7 @@ void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q,
  *  - >=0 - Index of the last futex that was awoken;
  *  - -1  - No futex was awoken
  */
-static int unqueue_multiple(struct futex_vector *v, int count)
+int futex_unqueue_multiple(struct futex_vector *v, int count)
 {
 	int ret = -1, i;
 
@@ -410,7 +410,7 @@ static int unqueue_multiple(struct futex_vector *v, int count)
  *  -  0 - Success
  *  - <0 - -EFAULT, -EWOULDBLOCK or -EINVAL
  */
-static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *woken)
+int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *woken)
 {
 	struct futex_hash_bucket *hb;
 	bool retry = false;
@@ -472,7 +472,7 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo
 		 * was woken, we don't return error and return this index to
 		 * userspace
 		 */
-		*woken = unqueue_multiple(vs, i);
+		*woken = futex_unqueue_multiple(vs, i);
 		if (*woken >= 0)
 			return 1;
 
@@ -557,7 +557,7 @@ int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
 
 		__set_current_state(TASK_RUNNING);
 
-		ret = unqueue_multiple(vs, count);
+		ret = futex_unqueue_multiple(vs, count);
 		if (ret >= 0)
 			return ret;