* [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem
@ 2025-09-29 14:48 buckzhang1212
2025-09-30 3:09 ` Waiman Long
0 siblings, 1 reply; 3+ messages in thread
From: buckzhang1212 @ 2025-09-29 14:48 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng,
Waiman Long, linux-kernel
Cc: buckzhang1212
From: "buck.zhang" <buckzhang1212@yeah.net>
Add the lock->magic check to warn invalid rwsem without initialization
Signed-off-by: buck.zhang <buckzhang1212@yeah.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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem
2025-09-29 14:48 [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem buckzhang1212
@ 2025-09-30 3:09 ` Waiman Long
[not found] ` <78363f7b.34166.19998b29e71.Coremail.buckzhang1212@yeah.net>
0 siblings, 1 reply; 3+ messages in thread
From: Waiman Long @ 2025-09-30 3:09 UTC (permalink / raw)
To: buckzhang1212, Peter Zijlstra, Ingo Molnar, Will Deacon,
Boqun Feng, linux-kernel
On 9/29/25 10:48 AM, buckzhang1212@yeah.net wrote:
> From: "buck.zhang" <buckzhang1212@yeah.net>
>
> Add the lock->magic check to warn invalid rwsem without initialization
>
> Signed-off-by: buck.zhang <buckzhang1212@yeah.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)))
Just to confirm that this patch will generate the needed warning for
your test case. Right?
Acked-by: Waiman Long <longman@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem
[not found] ` <78363f7b.34166.19998b29e71.Coremail.buckzhang1212@yeah.net>
@ 2025-09-30 14:36 ` Waiman Long
0 siblings, 0 replies; 3+ messages in thread
From: Waiman Long @ 2025-09-30 14:36 UTC (permalink / raw)
To: buckzhang1212, llong; +Cc: peterz, mingo, will, boqun.feng, linux-kernel
On 9/29/25 11:37 PM, buckzhang1212@yeah.net wrote:
> Hey Long
> Yes. I tested it yesterday. patch can provide the needed warning
> for my test case when enable CONFIG_DEBUG_RESEMES
>
>
Thanks for the confirmation.
Cheers,
Longman
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-09-29 14:48 [PATCH v3] locking/rwsem: add DEBUG_RWSEMS_WARN_ON to warn invalid rwsem buckzhang1212
2025-09-30 3:09 ` Waiman Long
[not found] ` <78363f7b.34166.19998b29e71.Coremail.buckzhang1212@yeah.net>
2025-09-30 14:36 ` Waiman Long
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