Re: [PATCH] netfilter: remove redundant skb check in nf_conntrack_put_reasm

[Phil Oester <kernel@linuxace.com>]

On Thu, Jun 20, 2013 at 11:58:46AM +0200, Pablo Neira Ayuso wrote:
> On Thu, Jun 20, 2013 at 11:22:59AM +0200, Florian Westphal wrote:
> > Phil Oester <kernel@linuxace.com> wrote:
> > > kfree_skb already checks for skb existence - remove redundant check from
> > > nf_conntrack_put_reasm.
> > 
> > This is called for every free'd skb, in almost all cases
> > the condition will be false.
> > 
> > So I think its ok to keep this check.
> 
> I see, we'll hit branch mispredictions most of the time. I have kept
> this back. Thanks Florian.

If we're concerned about branch mispredictions, we should change the check to
match the one at the top of kfree_skb:

        if (unlikely(!skb))
                return;

However nf_conntrack_put_reasm is only used in 3 places in the entire tree.
Unclear why we don't just call kfree_skb directly in these 3 places.

Phil