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Re: [PATCH] arp_queue: serializing unlink + kfree_skb

To: Werner Almesberger <wa@xxxxxxxxxxxxxxx>
Subject: Re: [PATCH] arp_queue: serializing unlink + kfree_skb
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 10 Feb 2005 15:56:47 +1100
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>, anton@xxxxxxxxx, okir@xxxxxxx, netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <20050210012304.E25338@xxxxxxxxxxxxxxx>
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On Thu, Feb 10, 2005 at 01:23:04AM -0300, Werner Almesberger wrote:
> 
> What happens if the operation could return a value, but the user
> ignores it ? E.g. if I don't like smp_mb__*, could I just use
> 
>       atomic_inc_and_test(foo);
> 
> instead of
> 
>       smp_mb__before_atomic_inc();
>       atomic_inc(foo);
>       smp_mb__after_atomic_dec();

Yes you can.

> ? If yes, is this a good idea ?

Dave mentioned that on sparc64, atomic_inc_and_test is much more
expensive than the second variant.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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