Subject: Re: [PATCH] brcmfmac: drop Inter-Access Point Protocol packets by default

From: Arend van Spriel <arend.vanspriel-dY08KVG/lbpWk0Htik3J/[email-masked]>
Date: Wed, 14 Mar 2018 21:55:23 +0100

On 3/14/2018 5:10 PM, Kalle Valo wrote:
> Rafał Miłecki <[email-masked]> writes:
>
>>>> +	unsigned char *eth_data = skb_mac_header(skb) + ETH_HLEN;
>>>> +#if !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
>>>
>>> #ifndef?
>>
>> I followed what is used in the include/linux/etherdevice.h. Is that a
>> good exceuse? Could it be there any some good reason for #if defined()?
>
> Don't know, maybe just a matter of taste? But it would be nice to know
> the background behind #ifdef vs #if defined(), never figured it out why
> two different forms.

Well. In this case you could use either one, but if you have more 
conditions #if defined() is bit more efficient:

#ifdef A
#ifdef B
#endif
#endif

vs.

#if defined(A) && defined(B)

Regards,
Arend