Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)
From: Ard Biesheuvel
Date: Fri Oct 14 2016 - 07:11:31 EST
On 14 October 2016 at 11:00, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote:
>> So why is the performance hit acceptable for ESP but not for WPA? We
>> could easily implement the same thing, i.e.,
>> kmalloc(GFP_ATOMIC)/kfree the aead_req struct rather than allocate it
>> on the stack
> Yeah, maybe we should. It's likely a much bigger allocation, but I
> don't actually know if that affects speed.
> In most cases where you want high performance we never hit this anyway
> since we'll have hardware crypto. I know for our (Intel's) devices we
> normally never hit these code paths.
> But on the other hand, you also did your changes for a reason, and the
> only reason I can see of that is performance. So you'd be the one with
> most "skin in the game", I guess?
Well, what sucks here is that the accelerated driver I implemented for
arm64 does not actually need this, as long as we take aad off the
stack. And note that the API was changed since my patch, to add aad
to the scatterlist: prior to this change, it used
aead_request_set_assoc() to set the associated data separately.