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From: Davidlohr Bueso <dave@stgolabs.net>
To: tglx@linutronix.de
Cc: mingo@redhat.com, peterz@infradead.org, dvhart@infradead.org,
	dave@stgolabs.net, linux-kernel@vger.kernel.org,
	Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH 3/4] kernel/futex: Move hb unlock out of unqueue_me_pi()
Date: Fri, 26 Feb 2021 09:50:28 -0800	[thread overview]
Message-ID: <20210226175029.50335-3-dave@stgolabs.net> (raw)
In-Reply-To: <20210226175029.50335-1-dave@stgolabs.net>

This improves the code readability, and the locking more obvious
as it becomes symmetric for the caller.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
 kernel/futex.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index ee09995d707b..dcd6132485e1 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2318,19 +2318,15 @@ static int unqueue_me(struct futex_q *q)
 
 /*
  * PI futexes can not be requeued and must remove themself from the
- * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry
- * and dropped here.
+ * hash bucket. The hash bucket lock (i.e. lock_ptr) is held.
  */
 static void unqueue_me_pi(struct futex_q *q)
-	__releases(q->lock_ptr)
 {
 	__unqueue_futex(q);
 
 	BUG_ON(!q->pi_state);
 	put_pi_state(q->pi_state);
 	q->pi_state = NULL;
-
-	spin_unlock(q->lock_ptr);
 }
 
 static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
@@ -2913,8 +2909,8 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
 	if (res)
 		ret = (res < 0) ? res : 0;
 
-	/* Unqueue and drop the lock */
 	unqueue_me_pi(&q);
+	spin_unlock(q.lock_ptr);
 	goto out;
 
 out_unlock_put_key:
@@ -3290,8 +3286,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		if (res)
 			ret = (res < 0) ? res : 0;
 
-		/* Unqueue and drop the lock. */
 		unqueue_me_pi(&q);
+		spin_unlock(q.lock_ptr);
 	}
 
 	if (ret == -EINTR) {
-- 
2.26.2


  parent reply	other threads:[~2021-02-26 17:52 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 17:50 [PATCH 1/4] kernel/futex: Kill rt_mutex_next_owner() Davidlohr Bueso
2021-02-26 17:50 ` [PATCH 2/4] kernel/futex: Make futex_wait_requeue_pi() only call fixup_owner() Davidlohr Bueso
2021-03-11 18:24   ` [tip: locking/core] " tip-bot2 for Davidlohr Bueso
2021-02-26 17:50 ` Davidlohr Bueso [this message]
2021-03-11 18:24   ` [tip: locking/core] kernel/futex: Move hb unlock out of unqueue_me_pi() tip-bot2 for Davidlohr Bueso
2021-02-26 17:50 ` [PATCH 4/4] kernel/futex: Explicitly document pi_lock for pi_state owner fixup Davidlohr Bueso
2021-03-11 18:24   ` [tip: locking/core] " tip-bot2 for Davidlohr Bueso
2021-03-01 15:19 ` [PATCH 1/4] kernel/futex: Kill rt_mutex_next_owner() Peter Zijlstra
2021-03-11 18:24 ` [tip: locking/core] " tip-bot2 for Davidlohr Bueso

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