linux-kernel - Re: [PATCH] staging: rtl8723bs: do not use assignment in if condition

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Date:   Fri, 22 Jun 2018 21:11:47 +0200
From:   Michael Straube <michael.straube@...teo.de>
To:     Joe Perches <joe@...ches.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8723bs: do not use assignment in if condition

On 06/22/18 19:28, Joe Perches wrote:
> On Fri, 2018-06-22 at 14:48 +0200, Michael Straube wrote:
>> On 06/22/18 12:57, Dan Carpenter wrote:
>>> On Fri, Jun 22, 2018 at 03:54:22AM -0700, Joe Perches wrote:
>>>> On Fri, 2018-06-22 at 13:40 +0300, Dan Carpenter wrote:
>>>>> On Thu, Jun 21, 2018 at 08:22:30PM +0200, Michael Straube wrote:
>>>>>> Fix checkpatch error 'do not use assignment in if condition'.
>>>> []
>>>>>> diff --git a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c b/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
>>>>>> index e55895632921..87a4ced41028 100644
>>>>>> --- a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
>>>>>> +++ b/
>>>>>> @@ -1181,9 +1181,8 @@ void rtw_macaddr_cfg(struct device *dev, u8 *mac_addr)
>>>>>>    	     (mac[3] == 0xff) && (mac[4] == 0xff) && (mac[5] == 0xff)) ||
>>>>>>    	    ((mac[0] == 0x00) && (mac[1] == 0x00) && (mac[2] == 0x00) &&
>>>>>>    	     (mac[3] == 0x00) && (mac[4] == 0x00) && (mac[5] == 0x00))) {
>>>>
>>>> Should also use is_broadcast_ether_addr and is_zero_ether_addr
>>>>
>>>>>> -		if (np &&
>>>>>> -		    (addr = of_get_property(np, "local-mac-address", &len)) &&
>>>>>> -		    len == ETH_ALEN) {
>>>>>> +		addr = of_get_property(np, "local-mac-address", &len);
>>>>>> +		if (np && addr && len == ETH_ALEN) {
>>>>>
>>>>> You can remove the "np" check.
>>>>>
>>>>> 		if (addr && len == ETH_ALEN) {
>>>>
>>>> It looks more like the rewrite is incorrect
>>>> as np is tested before of_get_property
>>>>
>>>
>>> That's what I was worried about too, but if "np" is NULL then
>>> of_get_property() just returns NULL so it's fine.
>>
>> So it should be this?
>>
>>           if (((mac[0] == 0xff) && (mac[1] == 0xff) && (mac[2] == 0xff) &&
>>                (mac[3] == 0xff) && (mac[4] == 0xff) && (mac[5] == 0xff)) ||
>>               ((mac[0] == 0x00) && (mac[1] == 0x00) && (mac[2] == 0x00) &&
>>                (mac[3] == 0x00) && (mac[4] == 0x00) && (mac[5] == 0x00)) &&
>>               (is_broadcast_ether_addr(mac) || is_zero_ether_addr(mac))) {
> 
> No as the mac[] tests are the same as is_<foo>_ether_addr

Ok, I understand now.

> and there's nothing really objectionable about embedding
> the assignment in the if here.
> 
> Output from checkpatch is not gospel and can be ignored
> whenever appropriate.

Ok, good to know.

> 		memcpy(mac_addr, ""\x00\xe0\x4c\x87\x00\x00", ETH_ALEN);
> 
> Although the last memcpy of a fixed mac address could
> probably use eth_random_addr to reduce the likelihood
> of mac address collision so maybe
> 
> 		eth_random_addr(mac_addr);
  
Using a random address would be preffered?


Thanks for your help and patience.
Michael