netdev - Re: [PATCH] xt_quota: don't copy quota back to userspace

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Date:	Fri, 23 Jul 2010 07:40:33 +0200
From:	Eric Dumazet <eric.dumazet@...il.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] xt_quota: don't copy quota back to userspace

Le vendredi 23 juillet 2010 à 07:27 +0200, Eric Dumazet a écrit :
> Le vendredi 23 juillet 2010 à 12:54 +0800, Changli Gao a écrit :
> > This patch should be applied after my another patch:
> > http://patchwork.ozlabs.org/patch/59729/
> > 
> > xt_quota: don't copy quota back to userspace
> > 
> > In nowadays, table entries are per-cpu variables, so it don't make any sense to
> > copy quota back to one of the variable instances. To keep things simple, this
> > patch undo the copy.
> > 
> > Signed-off-by: Changli Gao <xiaosuo@...il.com>
> 
> This looks the wrong way to fix this problem.
> 
> Also Changli, could you please _not_ include the title of your patches
> inside the Changelog ? This is useless.
> 

Reading again your patch, I understand only the Changelog is wrong.

We want to copy quota back to userspace, as specified when rule was
setup (so that iptables-save works)

The real thing you are doing is that we dont change the initial quota
during packet processing, only the private quota, shared by all cpus.

Before the patch , iptables -nvL could report an old and not accurate
quota value.

After the patch, iptables -nvL reports the initial quota value, not the
actual value.



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