linux-kernel - [PATCH] locking/rwsem: use OWNER_NONSPINNABLE directly instead of OWNER

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Message-ID: <20250610130158.4876-1-alexjlzheng@tencent.com>
Date: Tue, 10 Jun 2025 21:01:58 +0800
From: alexjlzheng@...il.com
To: peterz@...radead.org,
	will@...nel.org,
	boqun.feng@...il.com,
	longman@...hat.com
Cc: linux-kernel@...r.kernel.org,
	Jinliang Zheng <alexjlzheng@...cent.com>
Subject: [PATCH] locking/rwsem: use OWNER_NONSPINNABLE directly instead of OWNER_SPINNABLE

From: Jinliang Zheng <alexjlzheng@...cent.com>

After commit 7d43f1ce9dd0 ("locking/rwsem: Enable time-based spinning on
reader-owned rwsem"), OWNER_SPINNABLE contains all possible values except
OWNER_NONSPINNABLE, namely OWNER_NULL | OWNER_WRITER | OWNER_READER.

Therefore, it is better to use OWNER_NONSPINNABLE directly to determine
whether to exit optimistic spin.

And, remove useless OWNER_SPINNABLE to simplify the code.

Signed-off-by: Jinliang Zheng <alexjlzheng@...cent.com>
---
 kernel/locking/rwsem.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 2ddb827e3bea..8572dba95af4 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -727,8 +727,6 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
 	return ret;
 }
 
-#define OWNER_SPINNABLE		(OWNER_NULL | OWNER_WRITER | OWNER_READER)
-
 static inline enum owner_state
 rwsem_owner_state(struct task_struct *owner, unsigned long flags)
 {
@@ -835,7 +833,7 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
 		enum owner_state owner_state;
 
 		owner_state = rwsem_spin_on_owner(sem);
-		if (!(owner_state & OWNER_SPINNABLE))
+		if (owner_state == OWNER_NONSPINNABLE)
 			break;
 
 		/*
-- 
2.49.0