linux-kernel - [PATCH v9 01/11] futex: fixup futex_wait_setup [fold futex: Move futex_queue() into futex_wait

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Message-ID: <20250225170914.289358-2-bigeasy@linutronix.de>
Date: Tue, 25 Feb 2025 18:09:04 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org
Cc: André Almeida <andrealmeid@...lia.com>,
	Darren Hart <dvhart@...radead.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Waiman Long <longman@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v9 01/11] futex: fixup futex_wait_setup [fold futex: Move futex_queue() into futex_wait_setup()]

we could also make @task a bool signaling it is either NULL or current.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/futex/waitwake.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index 7655de59ab3d6..44034dee7a48c 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -571,7 +571,8 @@ int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
  * @val:	the expected value
  * @flags:	futex flags (FLAGS_SHARED, etc.)
  * @q:		the associated futex_q
- * @hb:		storage for hash_bucket pointer to be returned to caller
+ * @key2:	the second futex_key if used for requeue PI
+ * task:	Task queueing this futex
  *
  * Setup the futex_q and locate the hash_bucket.  Get the futex value and
  * compare it with the expected value.  Handle atomic faults internally.
@@ -634,7 +635,7 @@ int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
 
 		if (uval != val) {
 			futex_q_unlock(hb);
-			ret = -EWOULDBLOCK;
+			return -EWOULDBLOCK;
 		}
 
 		if (key2 && futex_match(&q->key, key2)) {
@@ -648,8 +649,9 @@ int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
 		 * futex_queue() calls spin_unlock() upon completion, both serializing
 		 * access to the hash list and forcing another memory barrier.
 		 */
-		set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
-		futex_queue(q, hb, current);
+		if (task == current)
+			set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
+		futex_queue(q, hb, task);
 	}
 
 	return ret;
-- 
2.47.2