Re: [PATCH] staging: rtl8192e: use is_zero_ether_addr() instead of memcmp()

[Eric Dumazet <eric.dumazet@gmail.com>]

On Thu, 2012-08-23 at 15:19 +0800, Wei Yongjun wrote:
> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
> 
> Using is_zero_ether_addr() instead of directly use
> memcmp() to determine if the ethernet address is all
> zeros.
> 
> spatch with a semantic match is used to found this problem.
> (http://coccinelle.lip6.fr/)
> 
> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
> ---
>  drivers/staging/rtl8192e/rtllib_softmac_wx.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/rtl8192e/rtllib_softmac_wx.c b/drivers/staging/rtl8192e/rtllib_softmac_wx.c
> index 1bb6b52..3cedfd9 100644
> --- a/drivers/staging/rtl8192e/rtllib_softmac_wx.c
> +++ b/drivers/staging/rtl8192e/rtllib_softmac_wx.c
> @@ -14,6 +14,8 @@
>   */
>  
> 
> +#include <linux/etherdevice.h>
> +
>  #include "rtllib.h"
>  #include "dot11d.h"
>  /* FIXME: add A freqs */
> @@ -137,7 +139,6 @@ int rtllib_wx_set_wap(struct rtllib_device *ieee,
>  {
>  
>  	int ret = 0;
> -	u8 zero[] = {0, 0, 0, 0, 0, 0};
>  	unsigned long flags;
>  
>  	short ifup = ieee->proto_started;
> @@ -157,7 +158,7 @@ int rtllib_wx_set_wap(struct rtllib_device *ieee,
>  		goto out;
>  	}
>  
> -	if (memcmp(temp->sa_data, zero, ETH_ALEN) == 0) {
> +	if (is_zero_ether_addr(temp->sa_data)) {
>  		spin_lock_irqsave(&ieee->lock, flags);
>  		memcpy(ieee->current_network.bssid, temp->sa_data, ETH_ALEN);

BTW this looks suspicious : Why is it using memcpy() if temp->sa_data is
known to be zero ?

>  		ieee->wap_set = 0;
> @@ -177,7 +178,7 @@ int rtllib_wx_set_wap(struct rtllib_device *ieee,
>  
>  	ieee->cannot_notify = false;
>  	memcpy(ieee->current_network.bssid, temp->sa_data, ETH_ALEN);
> -	ieee->wap_set = (memcmp(temp->sa_data, zero, ETH_ALEN) != 0);
> +	ieee->wap_set = (!is_zero_ether_addr(temp->sa_data));
>  
	ieee->wap_set = !is_zero_ether_addr(temp->sa_data);

>  	spin_unlock_irqrestore(&ieee->lock, flags);
>  
> 
> 
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