linux-kernel - Re: [PATCH v2] staging: vt6656: Use ARRAY

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Date:   Tue, 24 Mar 2020 09:54:56 +0000
From:   Quentin Deslandes <quentin.deslandes@...ev.co.uk>
To:     Oscar Carter <oscar.carter@....com>
Cc:     Forest Bond <forest@...ttletooquiet.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Malcolm Priestley <tvboxspy@...il.com>,
        Colin Ian King <colin.king@...onical.com>,
        Gabriela Bittencourt <gabrielabittencourt00@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: vt6656: Use ARRAY_SIZE instead of hardcoded
 size

On 03/18/20 18:40:15, Oscar Carter wrote:
> Use ARRAY_SIZE to replace the hardcoded size so we will never have a
> mismatch.
> 
> Signed-off-by: Oscar Carter <oscar.carter@....com>
> ---
> Changelog v1 -> v2
> - Use ARRAY_SIZE(priv->cck_pwr_tbl) everywhere instead of introducing a new
>   variable to hold its value.
> 
>  drivers/staging/vt6656/main_usb.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/vt6656/main_usb.c b/drivers/staging/vt6656/main_usb.c
> index 5e48b3ddb94c..acfcc11c3b61 100644
> --- a/drivers/staging/vt6656/main_usb.c
> +++ b/drivers/staging/vt6656/main_usb.c
> @@ -23,6 +23,7 @@
> 
>  #include <linux/etherdevice.h>
>  #include <linux/file.h>
> +#include <linux/kernel.h>
>  #include "device.h"
>  #include "card.h"
>  #include "baseband.h"
> @@ -145,7 +146,7 @@ static int vnt_init_registers(struct vnt_private *priv)
> 
>  	init_cmd->init_class = DEVICE_INIT_COLD;
>  	init_cmd->exist_sw_net_addr = priv->exist_sw_net_addr;
> -	for (ii = 0; ii < 6; ii++)
> +	for (ii = 0; ii < ARRAY_SIZE(init_cmd->sw_net_addr); ii++)
>  		init_cmd->sw_net_addr[ii] = priv->current_net_addr[ii];
>  	init_cmd->short_retry_limit = priv->short_retry_limit;
>  	init_cmd->long_retry_limit = priv->long_retry_limit;
> @@ -184,7 +185,7 @@ static int vnt_init_registers(struct vnt_private *priv)
>  	priv->cck_pwr = priv->eeprom[EEP_OFS_PWR_CCK];
>  	priv->ofdm_pwr_g = priv->eeprom[EEP_OFS_PWR_OFDMG];
>  	/* load power table */
> -	for (ii = 0; ii < 14; ii++) {
> +	for (ii = 0; ii < ARRAY_SIZE(priv->cck_pwr_tbl); ii++) {
>  		priv->cck_pwr_tbl[ii] =
>  			priv->eeprom[ii + EEP_OFS_CCK_PWR_TBL];
>  		if (priv->cck_pwr_tbl[ii] == 0)
> @@ -200,7 +201,7 @@ static int vnt_init_registers(struct vnt_private *priv)
>  	 * original zonetype is USA, but custom zonetype is Europe,
>  	 * then need to recover 12, 13, 14 channels with 11 channel
>  	 */
> -	for (ii = 11; ii < 14; ii++) {
> +	for (ii = 11; ii < ARRAY_SIZE(priv->cck_pwr_tbl); ii++) {
>  		priv->cck_pwr_tbl[ii] = priv->cck_pwr_tbl[10];
>  		priv->ofdm_pwr_tbl[ii] = priv->ofdm_pwr_tbl[10];
>  	}
> --
> 2.20.1
> 

Looks good, however are we certain priv->cck_pwr_tbl and
priv->ofdm_pwr_tbl are always the same size?

What about using a macro for cck_pwr_tbl and ofdm_pwr_tbl size in
device.h? Or a BUILD_BUG() if array's sizes are different? It could be
helpful for future developers to say these arrays must be the same size.

Thanks,
Quentin