linux-kernel - [tip: locking/futex] futex: Create helper function to initialize a hash slot

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Message-ID: <174670043329.406.8420566167058219767.tip-bot2@tip-bot2>
Date: Thu, 08 May 2025 10:33:53 -0000
From: "tip-bot2 for Sebastian Andrzej Siewior" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: locking/futex] futex: Create helper function to initialize a hash slot

The following commit has been merged into the locking/futex branch of tip:

Commit-ID:     9a9bdfdd687395a3dc949d3ae3323494395a93d4
Gitweb:        https://git.kernel.org/tip/9a9bdfdd687395a3dc949d3ae3323494395a93d4
Author:        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate:    Wed, 16 Apr 2025 18:29:11 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Sat, 03 May 2025 12:02:07 +02:00

futex: Create helper function to initialize a hash slot

Factor out the futex_hash_bucket initialisation into a helpr function.
The helper function will be used in a follow up patch implementing
process private hash buckets.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-12-bigeasy@linutronix.de
---
 kernel/futex/core.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 1443a98..afc6678 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1160,6 +1160,13 @@ void futex_exit_release(struct task_struct *tsk)
 	futex_cleanup_end(tsk, FUTEX_STATE_DEAD);
 }
 
+static void futex_hash_bucket_init(struct futex_hash_bucket *fhb)
+{
+	atomic_set(&fhb->waiters, 0);
+	plist_head_init(&fhb->chain);
+	spin_lock_init(&fhb->lock);
+}
+
 static int __init futex_init(void)
 {
 	unsigned long hashsize, i;
@@ -1177,11 +1184,8 @@ static int __init futex_init(void)
 					       hashsize, hashsize);
 	hashsize = 1UL << futex_shift;
 
-	for (i = 0; i < hashsize; i++) {
-		atomic_set(&futex_queues[i].waiters, 0);
-		plist_head_init(&futex_queues[i].chain);
-		spin_lock_init(&futex_queues[i].lock);
-	}
+	for (i = 0; i < hashsize; i++)
+		futex_hash_bucket_init(&futex_queues[i]);
 
 	futex_hashmask = hashsize - 1;
 	return 0;