linux-kernel - Re: [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless

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Date:	Thu, 13 Nov 2014 20:17:39 +0000
From:	David Howells <dhowells@...hat.com>
To:	Pranith Kumar <bobby.prani@...il.com>
Cc:	dhowells@...hat.com, "David S. Miller" <davem@...emloft.net>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	netdev@...r.kernel.org (open list:NETWORKING [GENERAL]),
	linux-kernel@...r.kernel.org (open list),
	paulmck@...ux.vnet.ibm.com
Subject: Re: [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()

Pranith Kumar <bobby.prani@...il.com> wrote:

>  	     loop != call->acks_head || stop;
>  	     loop = (loop + 1) &  (call->acks_winsz - 1)
>  	     ) {
> -		p_txb = call->acks_window + loop;
> -		smp_read_barrier_depends();
> +		p_txb = lockless_dereference(call)->acks_window + loop;

Nack.  You've stuck an implicit barrier on a dereference that doesn't matter.
And similar for other hunks of this patch.

David
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