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SubjectRe: [Patch v5] rwsem: fix rwsem_is_locked() bugs
Andrew Morton wrote:
> On Wed, 14 Oct 2009 05:52:22 -0400
> Amerigo Wang <amwang@redhat.com> wrote:
>
>> --- a/include/linux/rwsem-spinlock.h
>> +++ b/include/linux/rwsem-spinlock.h
>> @@ -68,11 +68,9 @@ extern int __down_write_trylock(struct rw_semaphore *sem);
>> extern void __up_read(struct rw_semaphore *sem);
>> extern void __up_write(struct rw_semaphore *sem);
>> extern void __downgrade_write(struct rw_semaphore *sem);
>> +extern int __rwsem_is_locked(struct rw_semaphore *sem);
>>
>> -static inline int rwsem_is_locked(struct rw_semaphore *sem)
>> -{
>> - return (sem->activity != 0);
>> -}
>> +#define rwsem_is_locked(sem) __rwsem_is_locked(sem)
>>
>> #endif /* __KERNEL__ */
>> #endif /* _LINUX_RWSEM_SPINLOCK_H */
>> diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
>> index 9df3ca5..7014306 100644
>> --- a/lib/rwsem-spinlock.c
>> +++ b/lib/rwsem-spinlock.c
>> @@ -17,6 +17,19 @@ struct rwsem_waiter {
>> #define RWSEM_WAITING_FOR_WRITE 0x00000002
>> };
>>
>> +int __rwsem_is_locked(struct rw_semaphore *sem)
>> +{
>> + int ret = 1;
>> + unsigned long flags;
>> +
>> + if (spin_trylock_irqsave(&sem->wait_lock, flags)) {
>> + ret = (sem->activity != 0);
>> + spin_unlock_irqrestore(&sem->wait_lock, flags);
>> + }
>> + return ret;
>> +}
>> +EXPORT_SYMBOL(__rwsem_is_locked);
>
> Why the macro tricks? Can we do


Yes, better.

Thanks for your patch!

>
> --- a/include/linux/rwsem-spinlock.h~rwsem-fix-rwsem_is_locked-bugs-fix
> +++ a/include/linux/rwsem-spinlock.h
> @@ -68,9 +68,7 @@ extern int __down_write_trylock(struct r
> extern void __up_read(struct rw_semaphore *sem);
> extern void __up_write(struct rw_semaphore *sem);
> extern void __downgrade_write(struct rw_semaphore *sem);
> -extern int __rwsem_is_locked(struct rw_semaphore *sem);
> -
> -#define rwsem_is_locked(sem) __rwsem_is_locked(sem)
> +extern int rwsem_is_locked(struct rw_semaphore *sem);
>
> #endif /* __KERNEL__ */
> #endif /* _LINUX_RWSEM_SPINLOCK_H */
> --- a/lib/rwsem-spinlock.c~rwsem-fix-rwsem_is_locked-bugs-fix
> +++ a/lib/rwsem-spinlock.c
> @@ -17,7 +17,7 @@ struct rwsem_waiter {
> #define RWSEM_WAITING_FOR_WRITE 0x00000002
> };
>
> -int __rwsem_is_locked(struct rw_semaphore *sem)
> +int rwsem_is_locked(struct rw_semaphore *sem)
> {
> int ret = 1;
> unsigned long flags;
> @@ -28,7 +28,7 @@ int __rwsem_is_locked(struct rw_semaphor
> }
> return ret;
> }
> -EXPORT_SYMBOL(__rwsem_is_locked);
> +EXPORT_SYMBOL(rwsem_is_locked);
>
> /*
> * initialise the semaphore
> _
>



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