linux-kernel - [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN

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Message-Id: <20250929144812.2211-1-buckzhang1212@yeah.net>
Date: Mon, 29 Sep 2025 07:48:12 -0700
From: buckzhang1212@...h.net
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Waiman Long <longman@...hat.com>,
	linux-kernel@...r.kernel.org
Cc: buckzhang1212@...h.net
Subject: [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem

From: "buck.zhang" <buckzhang1212@...h.net>

Add the lock->magic check to warn invalid rwsem without initialization

Signed-off-by: buck.zhang <buckzhang1212@...h.net>

---
Changes in v3:
  - Use the lock->magic check in __down_read_common/__down_write_common
  - (Suggested by Waiman Long)
---
 kernel/locking/rwsem.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 24df4d98f..38d884643 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1256,6 +1256,9 @@ static __always_inline int __down_read_common(struct rw_semaphore *sem, int stat
 	int ret = 0;
 	long count;
 
+	/* add the lock->magic check to warn the invalid rwsem without initialization */
+	DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
+
 	preempt_disable();
 	if (!rwsem_read_trylock(sem, &count)) {
 		if (IS_ERR(rwsem_down_read_slowpath(sem, count, state))) {
@@ -1312,6 +1315,9 @@ static __always_inline int __down_write_common(struct rw_semaphore *sem, int sta
 {
 	int ret = 0;
 
+	/* add the lock->magic check to warn the invalid rwsem without initialization */
+	DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
+
 	preempt_disable();
 	if (unlikely(!rwsem_write_trylock(sem))) {
 		if (IS_ERR(rwsem_down_write_slowpath(sem, state)))
-- 
2.17.1