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

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Message-ID: <1476439212.31114.37.camel@sipsolutions.net>
Date:   Fri, 14 Oct 2016 12:00:12 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        "linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Linux Wireless List <linux-wireless@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jouni Malinen <j@...fi>
Subject: Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)


> 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?

johannes