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

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Message-ID: <5dc3eb9d-229c-b086-9d1a-f695e94f8752@colorfullife.com>
Date:   Wed, 25 May 2022 21:26:20 +0200
From:   Manfred Spraul <manfred@...orfullife.com>
To:     Gautam Menghani <gautammenghani201@...il.com>,
        akpm@...ux-foundation.org, shakeelb@...gle.com,
        vasily.averin@...ux.dev, mhocko@...e.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 20:22, 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>
Reviewed-by: Manfred Spraul <manfred@...orfullife.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;
>   

A copy/paste mistake: The 1st loop in perform_atomic_semop() needs 
result - because it must check for overflows.

The 2nd loop doesn't need it.

>   		if (sop->sem_flg & SEM_UNDO) {
>   			int undo = un->semadj[sop->sem_num] - sem_op;

--

     Manfred