futex: Simplify handle_early_requeue_pi_wakeup()

Move the futex key match out of handle_early_requeue_pi_wakeup() which
allows to simplify that function. The upcoming state machine for
requeue_pi() will make that go away.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.638938670@linutronix.de

diff --git a/kernel/futex.c b/kernel/futex.c
index a5232f6..82660b9 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3070,27 +3070,22 @@ pi_faulted:
 }
 
 /**
- * handle_early_requeue_pi_wakeup() - Detect early wakeup on the initial futex
+ * handle_early_requeue_pi_wakeup() - Handle early wakeup on the initial futex
  * @hb:                the hash_bucket futex_q was original enqueued on
  * @q:         the futex_q woken while waiting to be requeued
- * @key2:      the futex_key of the requeue target futex
  * @timeout:   the timeout associated with the wait (NULL if none)
  *
- * Detect if the task was woken on the initial futex as opposed to the requeue
- * target futex.  If so, determine if it was a timeout or a signal that caused
- * the wakeup and return the appropriate error code to the caller.  Must be
- * called with the hb lock held.
+ * Determine the cause for the early wakeup.
  *
  * Return:
- *  -  0 = no early wakeup detected;
- *  - <0 = -ETIMEDOUT or -ERESTARTNOINTR
+ *  -EWOULDBLOCK or -ETIMEDOUT or -ERESTARTNOINTR
  */
 static inline
 int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
-                                  struct futex_q *q, union futex_key *key2,
+                                  struct futex_q *q,
                                   struct hrtimer_sleeper *timeout)
 {
-       int ret = 0;
+       int ret;
 
        /*
         * With the hb lock held, we avoid races while we process the wakeup.
@@ -3099,22 +3094,21 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
         * It can't be requeued from uaddr2 to something else since we don't
         * support a PI aware source futex for requeue.
         */
-       if (!match_futex(&q->key, key2)) {
-               WARN_ON(q->lock_ptr && (&hb->lock != q->lock_ptr));
-               /*
-                * We were woken prior to requeue by a timeout or a signal.
-                * Unqueue the futex_q and determine which it was.
-                */
-               plist_del(&q->list, &hb->chain);
-               hb_waiters_dec(hb);
+       WARN_ON_ONCE(&hb->lock != q->lock_ptr);
 
-               /* Handle spurious wakeups gracefully */
-               ret = -EWOULDBLOCK;
-               if (timeout && !timeout->task)
-                       ret = -ETIMEDOUT;
-               else if (signal_pending(current))
-                       ret = -ERESTARTNOINTR;
-       }
+       /*
+        * We were woken prior to requeue by a timeout or a signal.
+        * Unqueue the futex_q and determine which it was.
+        */
+       plist_del(&q->list, &hb->chain);
+       hb_waiters_dec(hb);
+
+       /* Handle spurious wakeups gracefully */
+       ret = -EWOULDBLOCK;
+       if (timeout && !timeout->task)
+               ret = -ETIMEDOUT;
+       else if (signal_pending(current))
+               ret = -ERESTARTNOINTR;
        return ret;
 }
 
@@ -3217,7 +3211,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
        futex_wait_queue_me(hb, &q, to);
 
        spin_lock(&hb->lock);
-       ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
+       /* Is @q still queued on uaddr1? */
+       if (!match_futex(&q->key, key2))
+               ret = handle_early_requeue_pi_wakeup(hb, &q, to);
        spin_unlock(&hb->lock);
        if (ret)
                goto out;