linux-kernel - Re: [PATCH] locking/rwsem: Remove an unused parameter of rwsem

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Message-ID: <a9be100c-b7b5-4353-37ea-e88d06bc5d2f@redhat.com>
Date:   Tue, 6 Jul 2021 08:52:53 -0400
From:   Waiman Long <llong@...hat.com>
To:     Yehan Xu <yehanxu1@...il.com>, peterz@...radead.org,
        mingo@...hat.com, will@...nel.org
Cc:     boqun.feng@...il.com, linux-kernel@...r.kernel.org,
        xuyehan <xuyehan@...omi.com>
Subject: Re: [PATCH] locking/rwsem: Remove an unused parameter of rwsem_wake()

On 7/6/21 12:50 AM, Yehan Xu wrote:
> From: xuyehan <xuyehan@...omi.com>
>
> The 2nd parameter 'count' is not used in this function.
> The places where the function is called are also modified.
>
> Signed-off-by: xuyehan <xuyehan@...omi.com>
> ---
>   kernel/locking/rwsem.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
> index 16bfbb1..8a595b6 100644
> --- a/kernel/locking/rwsem.c
> +++ b/kernel/locking/rwsem.c
> @@ -1165,7 +1165,7 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)
>    * handle waking up a waiter on the semaphore
>    * - up_read/up_write has decremented the active part of count if we come here
>    */
> -static struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem, long count)
> +static struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem)
>   {
>   	unsigned long flags;
>   	DEFINE_WAKE_Q(wake_q);
> @@ -1297,7 +1297,7 @@ static inline void __up_read(struct rw_semaphore *sem)
>   	if (unlikely((tmp & (RWSEM_LOCK_MASK|RWSEM_FLAG_WAITERS)) ==
>   		      RWSEM_FLAG_WAITERS)) {
>   		clear_nonspinnable(sem);
> -		rwsem_wake(sem, tmp);
> +		rwsem_wake(sem);
>   	}
>   }
>   
> @@ -1319,7 +1319,7 @@ static inline void __up_write(struct rw_semaphore *sem)
>   	rwsem_clear_owner(sem);
>   	tmp = atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED, &sem->count);
>   	if (unlikely(tmp & RWSEM_FLAG_WAITERS))
> -		rwsem_wake(sem, tmp);
> +		rwsem_wake(sem);
>   }
>   
>   /*

Right, the count parameter was added in the past for some optimization 
which had since been taken out. So it is no longer needed.

Acked-by: Waiman Long <longman@...hat.com>