netdev - Re: [PATCH] can: softing: Remove redundant variable ptr

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Message-ID: <20210426122450.v2qxdxjk52d5dh6o@pengutronix.de>
Date:   Mon, 26 Apr 2021 14:24:50 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
Cc:     wg@...ndegger.com, davem@...emloft.net, kuba@...nel.org,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: softing: Remove redundant variable ptr

On 26.04.2021 18:08:16, Jiapeng Chong wrote:
> Variable ptr is being assigned a value from a calculation
> however the variable is never read, 
                       ^^^^^^^^^^^^^

This is not 100% correct.

The variable ptr is read from, see a line directly above the line this
patch removes.

> so this redundant variable can be removed.

This patch doesn't remove the variable.

> Cleans up the following clang-analyzer warning:
> 
> drivers/net/can/softing/softing_main.c:279:3: warning: Value stored to
> 'ptr' is never read [clang-analyzer-deadcode.DeadStores].
> 
> drivers/net/can/softing/softing_main.c:242:3: warning: Value stored to
> 'ptr' is never read [clang-analyzer-deadcode.DeadStores].

The clang warning is more precise: the value stored to ptr in the
calculations this patch removes is not used, so the calculation and the
assignment can be removed.

> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
> ---
>  drivers/net/can/softing/softing_main.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/net/can/softing/softing_main.c b/drivers/net/can/softing/softing_main.c
> index c44f341..cfc1325 100644
> --- a/drivers/net/can/softing/softing_main.c
> +++ b/drivers/net/can/softing/softing_main.c
> @@ -239,7 +239,6 @@ static int softing_handle_1(struct softing *card)
>  				DPRAM_INFO_BUSSTATE2 : DPRAM_INFO_BUSSTATE]);
>  		/* timestamp */
>  		tmp_u32 = le32_to_cpup((void *)ptr);
> -		ptr += 4;
>  		ktime = softing_raw2ktime(card, tmp_u32);
>  
>  		++netdev->stats.rx_errors;
> @@ -276,7 +275,6 @@ static int softing_handle_1(struct softing *card)
>  		ktime = softing_raw2ktime(card, tmp_u32);
>  		if (!(msg.can_id & CAN_RTR_FLAG))
>  			memcpy(&msg.data[0], ptr, 8);
> -		ptr += 8;
>  		/* update socket */
>  		if (cmd & CMD_ACK) {
>  			/* acknowledge, was tx msg */
> -- 
> 1.8.3.1
> 
>

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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