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Re: [PATCH] arp_queue: serializing unlink + kfree_skb

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: Re: [PATCH] arp_queue: serializing unlink + kfree_skb
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 4 Feb 2005 10:50:44 +1100
Cc: anton@xxxxxxxxx, okir@xxxxxxx, netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <20050203141901.5ce04c92.davem@xxxxxxxxxxxxx>
References: <20050131102920.GC4170@xxxxxxx> <E1CvZo6-0001Bz-00@xxxxxxxxxxxxxxxxxxxxxxxx> <20050203142705.GA11318@xxxxxxxxxxxxxxxxxxxxxxxxxx> <20050203203010.GA7081@xxxxxxxxxxxxxxxxxxx> <20050203141901.5ce04c92.davem@xxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mutt/1.5.6+20040722i
On Thu, Feb 03, 2005 at 02:19:01PM -0800, David S. Miller wrote:
> 
> They are for cases where you want strict ordering even for the
> non-return-value-giving atomic_t ops.

I see.  I got atomic_dec and atomic_dec_and_test mixed up.

So the problem isn't as big as I thought which is good.  sk_buff
is only in trouble because of the atomic_read optimisation which
really needs a memory barrier.

However, instead of adding a memory barrier which makes the optimisation
less useful, let's just get rid of the atomic_read.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Thanks for the document, it's really helpful.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

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