linux-kernel - Re: [PATCH v5] staging: xgifb: correct the multiple line dereference

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Date:   Mon, 27 Feb 2017 22:11:45 -0800
From:   Joe Perches <joe@...ches.com>
To:     Arushi Singhal <arushisinghal19971997@...il.com>,
        arnaud.patard@...-net.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        outreachy-kernel@...glegroups.com
Subject: Re: [PATCH v5] staging: xgifb: correct the multiple line dereference

On Tue, 2017-02-28 at 07:55 +0530, Arushi Singhal wrote:
> Error reported by checkpatch.pl as "avoid multiple line dereference".
> Addition of new variables to make the code more readable and also to
> correct about mentioned error as by itroducing new variables line is
> not exceeding 80 characters.
[]
> diff --git a/drivers/staging/xgifb/vb_setmode.c b/drivers/staging/xgifb/vb_setmode.c
[]
> @@ -221,8 +221,11 @@ static unsigned char XGI_AjustCRT2Rate(unsigned short ModeIdIndex,
>  
>  	for (; XGI330_RefIndex[RefreshRateTableIndex + (*i)].ModeID ==
>  	       tempbx; (*i)--) {
> -		infoflag = XGI330_RefIndex[RefreshRateTableIndex + (*i)].
> -				Ext_InfoFlag;
> +		int j;
> +
> +		j = XGI330_RefIndex[RefreshRateTableIndex + (*i)].Ext_InfoFlag;
> +		infoflag = j;

Better would be to introduce a temporary like:

	const struct XGI_Ext2Struct *ext2;

	[code...]

	ext2 = &XGI330_RefIndex[RefreshRateTableIndex];

	and then index that like

	for (; ext2[*i].ModeID == tempbx; (*i)--) {
		infoflag = ext2[*i].Ext_InfoFlag;

> +
>  		if (infoflag & tempax)
>  			return 1;
>  
> @@ -231,8 +234,11 @@ static unsigned char XGI_AjustCRT2Rate(unsigned short ModeIdIndex,
>  	}
>  
>  	for ((*i) = 0;; (*i)++) {
> -		infoflag = XGI330_RefIndex[RefreshRateTableIndex + (*i)].
> -				Ext_InfoFlag;

etc...