linux-kernel - Re: [PATCH net] staging: rtl8188eu: use is_zero_ether

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Date:   Tue, 12 Mar 2019 14:58:36 +0800
From:   maowenan <maowenan@...wei.com>
To:     Joe Perches <joe@...ches.com>, <Larry.Finger@...inger.net>,
        <gregkh@...uxfoundation.org>, <straube.linux@...il.com>,
        <jananis37@...il.com>, <devel@...verdev.osuosl.org>,
        <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>,
        <davem@...emloft.net>
Subject: Re: [PATCH net] staging: rtl8188eu: use is_zero_ether_addr() instead
 of memcmp()



On 2019/3/12 14:35, Joe Perches wrote:
> On Tue, 2019-03-12 at 14:29 +0800, maowenan wrote:
>> ping...
>>
>> On 2019/3/9 11:26, Mao Wenan wrote:
>>> Using is_zero_ether_addr() instead of directly use
>>> memcmp() to determine if the ethernet address is all
>>> zeros.
> []
>>> diff --git a/drivers/staging/rtl8188eu/core/rtw_mlme.c b/drivers/staging/rtl8188eu/core/rtw_mlme.c
> []
>>> @@ -180,9 +180,8 @@ struct wlan_network *rtw_find_network(struct __queue *scanned_queue, u8 *addr)
>>>  {
>>>  	struct list_head *phead, *plist;
>>>  	struct wlan_network *pnetwork = NULL;
>>> -	u8 zero_addr[ETH_ALEN] = {0, 0, 0, 0, 0, 0};
>>>  
>>> -	if (!memcmp(zero_addr, addr, ETH_ALEN)) {
>>> +	if (is_zero_ether_addr(addr)) {
> 
> How did you verify that addr is __aligned(2)?

/**
 * is_zero_ether_addr - Determine if give Ethernet address is all zeros.
 * @addr: Pointer to a six-byte array containing the Ethernet address
 *
 * Return true if the address is all zeroes.
 */
I think they are completely equivalent functions, no need to check addr is __aligned(2),
because addr may be defined as unsigned char MacAddress[ETH_ALEN]; the length is 6.
> 
> 
> 
> .
>