linux-kernel - Re: [PATCH] netfilter: nf_conntrack: use safer way to lock all buckets

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Date:	Wed, 13 Jan 2016 17:54:23 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	Florian Westphal <fw@...len.de>, kaber@...sh.net,
	kadlec@...ckhole.kfki.hu, davem@...emloft.net,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: nf_conntrack: use safer way to lock all
 buckets

On Sun, Jan 10, 2016 at 02:06:37AM +0100, Florian Westphal wrote:
> Sasha Levin <sasha.levin@...cle.com> wrote:
> > Fix this by using a global lock and synchronize all buckets on it when we
> > need to lock them all. This is pretty heavyweight, but is only done when we
> > need to resize the hashtable, and that doesn't happen often enough (or at all).
> 
> > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> > index 3cb3cb8..3c008ce 100644
> > --- a/net/netfilter/nf_conntrack_core.c
> > +++ b/net/netfilter/nf_conntrack_core.c
> > @@ -66,6 +66,32 @@ EXPORT_SYMBOL_GPL(nf_conntrack_locks);
> >  __cacheline_aligned_in_smp DEFINE_SPINLOCK(nf_conntrack_expect_lock);
> >  EXPORT_SYMBOL_GPL(nf_conntrack_expect_lock);
> >  
> > +spinlock_t nf_conntrack_locks_all_lock;
> > +bool nf_conntrack_locks_all;
> 
> Seems both of these can be static and __read_mostly too --
> as you already note resizing virtually never happens.
>
> Otherwise:
> Reviewed-by: Florian Westphal <fw@...len.de>

Sasha, would you resubmit addressing Florian's feedback?

Thanks.