[PATCH] netfilter: remove an atomic bit operation

[PATCH] netfilter: remove an atomic bit operation

[Changli Gao]

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@gmail.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

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

[Tim Gardner]

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@gmail.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@canonical.com

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

[Eric Dumazet]

Le samedi 20 novembre 2010 à 09:03 -0700, Tim Gardner a écrit :
> 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@gmail.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
> > --

> 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;
> 

Or

	__set_bit(IPS_CONFIRMED_BIT, &ct->status);


set_bit() is atomic, while __set_bit() is not



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

[Changli Gao]

On Sun, Nov 21, 2010 at 12:50 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Le samedi 20 novembre 2010 à 09:03 -0700, Tim Gardner a écrit :
>
>> 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;
>>
>
> Or
>
>        __set_bit(IPS_CONFIRMED_BIT, &ct->status);
>
>
> set_bit() is atomic, while __set_bit() is not
>

Oh, you are right. Thanks. My a previous patch accepted by Patrick has
the same problem.

-- 
Regards,
Changli Gao(xiaosuo@gmail.com)
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