netdev - Re: [PATCH] netfilter: remove an atomic bit operation

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Message-ID: <4CE7F160.9050107@canonical.com>
Date:	Sat, 20 Nov 2010 09:03:44 -0700
From:	Tim Gardner <tim.gardner@...onical.com>
To:	Changli Gao <xiaosuo@...il.com>
CC:	Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] netfilter: remove an atomic bit operation

On 11/20/2010 12:55 AM, Changli Gao wrote:
> As this ct won't be seen by the others, we don't need to set the
> IPS_CONFIRMED_BIT in atomic way.
>
> Signed-off-by: Changli Gao<xiaosuo@...il.com>
> ---
>   net/netfilter/nf_conntrack_core.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> index 27a5ea6..c708248 100644
> --- a/net/netfilter/nf_conntrack_core.c
> +++ b/net/netfilter/nf_conntrack_core.c
> @@ -486,7 +486,7 @@ __nf_conntrack_confirm(struct sk_buff *skb)
>   	ct->timeout.expires += jiffies;
>   	add_timer(&ct->timeout);
>   	atomic_inc(&ct->ct_general.use);
> -	set_bit(IPS_CONFIRMED_BIT,&ct->status);
> +	ct->status |= IPS_CONFIRMED_BIT;
>
>   	/* Since the lookup is lockless, hash insertion must be done after
>   	 * starting the timer and setting the CONFIRMED bit. The RCU barriers
> --
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NAK, set_bit() takes a bit number, not a mask. That is, assuming you can 
get away with a non-atomic operation on this field. I'll defer to 
Patrick on that.

I think you have to use IPS_CONFIRMED instead, e.g.,

	ct->status |= IPS_CONFIRMED;

rtg
-- 
Tim Gardner tim.gardner@...onical.com
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