Re: [PATCH 2/2] mac80211: Monitor mode radiotap-based packet injection

[Andy Green <andy@warmcat.com>]

Michael Wu wrote:

> I've mostly made comments about style issues. There are only comments on the 
> first instance of any style problem so please check the rest of the code for 
> the same problems.

Thanks for this feedback Michael.  I have changed all the style problems 
my eyes could see, assisted by visiting every = in the patch.

> Hm, this could be integrated into the switch statement below, but it doesn't 
> really matter much.

It's also very handy for...

> Have you looked into padding issues with radiotap headers? For example, if 
> there is a 1 byte field which is then followed by a 4 byte field, there needs 
> to be 3 bytes of padding after the first field, but if the field after were 2 
> bytes long, the padding would only be 1 byte (according to my understanding 
> of the radiotap specs).

I googled for radiotap specs but I didn't find anything useful.  I added 
some small code to enforce the alignment rules you mention above.

I found there was no docs in ./Documentation about 80211, I added a 
small explanation and examples about injection including this alignment 
Gotcha so the knowledge isn't lost.

> We could avoid this check altogether by spinning this code into a different 
> function and setting the xmit handler appropriately depending on if we're 
> initializing/switching to a monitor interface or not. Not entirely sure if 
> it's worth it, but I thought I'd mention it.

Yes, that method would be marginally better, but there is only a single 
int getting tested in the main path and even that is marked up as 
unlikely().  So I leave it as it is for now.

-Andy