netdev - Re: [PATCH] skbuff: make skb_put

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Message-ID: <1497567312.14396.28.camel@perches.com>
Date:   Thu, 15 Jun 2017 15:55:12 -0700
From:   Joe Perches <joe@...ches.com>
To:     Johannes Berg <johannes@...solutions.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] skbuff: make skb_put_zero() return void

On Fri, 2017-06-16 at 00:17 +0200, Johannes Berg wrote:
> On Wed, 2017-06-14 at 14:18 -0700, Joe Perches wrote:
> > On Wed, 2017-06-14 at 22:40 +0200, Johannes Berg wrote:
> > > On Wed, 2017-06-14 at 13:36 -0700, Joe Perches wrote:
> > > > 
> > > > Given you are adding a lot of these, it might be better
> > > > to add an exported function that duplicates most of
> > > > skb_put with a memset at the end.
> > > 
> > > Yeah, could be done. I'm not sure why you'd want to duplicate it
> > > rather
> > > than call it though? To make it about as fast?
> > 
> > Yeah, that and reduced stack use.
> > 
> > Dunno how performance sensitive these uses really are
> > but it seems some might be for slow cpu wireless APs in
> > both the rx and tx paths.
> 
> I haven't really checked now, but the wireless (mac80211) ones I saw
> weren't in the data TX/RX, only for management SKBs which are pretty
> much a slowpath.
> 
> Anyway, I guess you know how to propose a patch with this :-)

I'll wait as I don't want to cause patch conflicts.

> However, I think in that case there should be something like
> skb_pull_inline, so that the skb_put code here isn't all copied around,
> but just lives in a single place that gets inlined into skb_put() and
> skb_put_zero().

Seems sensible.