linux-kernel - Re: [PATCH] ipc: Remove dead code in perform_atomic

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Date:   Wed, 25 May 2022 02:12:44 +0300
From:   vasily.averin@...ux.dev
To:     Gautam Menghani <gautammenghani201@...il.com>,
        akpm@...ux-foundation.org, shakeelb@...gle.com, mhocko@...e.com,
        manfred@...orfullife.com
Cc:     linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        skhan@...uxfoundation.org
Subject: Re: [PATCH] ipc: Remove dead code in perform_atomic_semop()

On 5/24/22 21:22, Gautam Menghani wrote:
> Remove the line which is dead code. Fixes the clang scan warning:
> warning: Value stored to 'result' is never read [deadcode.DeadStores]
>                 result = curr->semval;
> 
> Signed-off-by: Gautam Menghani <gautammenghani201@...il.com>
> ---
>  ipc/sem.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/ipc/sem.c b/ipc/sem.c
> index 0dbdb98fdf2d..156824bcda47 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -766,7 +766,6 @@ static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q)
>  	for (sop = sops; sop < sops + nsops; sop++) {
>  		curr = &sma->sems[sop->sem_num];
>  		sem_op = sop->sem_op;
> -		result = curr->semval;
>  
>  		if (sop->sem_flg & SEM_UNDO) {
>  			int undo = un->semadj[sop->sem_num] - sem_op;

Perhaps it would be better to keep the "result" but use it in the
marked line below, like it was done in previous part of this function?

                        un->semadj[sop->sem_num] = undo;
                }
                curr->semval += sem_op; <<<<<< VvS: here ?
                ipc_update_pid(&curr->sempid, q->pid);

Thank you,
	Vasily Averin