Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)

From: Johannes Berg
Date: Fri Oct 14 2016 - 05:26:06 EST

On Fri, 2016-10-14 at 10:21 +0100, Ard Biesheuvel wrote:

> It is annotated with a TODO, though :-)
> 38320c70d282b (Herbert XuÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ2008-01-28 19:35:05
> -0800ÂÂ41)
> Â* TODO: Use spare space in skb for this where possible.

I saw that, but I don't think generally there will be spare space for
it - the stuff there is likely far too big. Anyway ... same problem
that we have.

I'm not inclined to allocate ~500 bytes temporarily for every frame
either though.

Maybe we could try to manage it in mac80211, we'd "only" need 5 AEAD
structs (which are today on the stack) in parallel for each key (4 TX,
1 RX), but in a typical case of having 3 keys that's already 7.5K worth
of memory that we almost never use. Again, with more complexity, we
could know that the TX will not be used if the driver does the TX, but
the single RX one we'd need unconditionally... decisions decisions...