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

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Date:	Thu, 14 Jan 2016 15:14:04 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	brouer@...hat.com, pablo@...filter.org, 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 Mon,  4 Jan 2016 21:25:46 -0500
Sasha Levin <sasha.levin@...cle.com> wrote:

> When we need to lock all buckets in the connection hashtable we'd attempt to
> lock 1024 spinlocks, which is way more preemption levels than supported by
> the kernel. Furthermore, this behavior was hidden by checking if lockdep is
> enabled, and if it was - use only 8 buckets(!).
> 
> 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).
> 
> Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> ---

Looks good to me, and I like the idea.

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer