linux-kernel - Re: [PATCH 02/16] doc: memory-barriers.txt: Document use of lockless

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Message-ID: <20141113201115.GR4460@linux.vnet.ibm.com>
Date:	Thu, 13 Nov 2014 12:11:15 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Pranith Kumar <bobby.prani@...il.com>
Cc:	Jonathan Corbet <corbet@....net>,
	"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/16] doc: memory-barriers.txt: Document use of
 lockless_dereference()

On Thu, Nov 13, 2014 at 02:24:08PM -0500, Pranith Kumar wrote:
> Recently lockless_dereference() was added which can be used in place of
> hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
> 
> Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
> ---
>  Documentation/memory-barriers.txt | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
> index 3d5f49b..841ac36 100644
> --- a/Documentation/memory-barriers.txt
> +++ b/Documentation/memory-barriers.txt
> @@ -203,7 +203,7 @@ There are some minimal guarantees that may be expected of a CPU:
>       and always in that order.  On most systems, smp_read_barrier_depends()
>       does nothing, but it is required for DEC Alpha.  The ACCESS_ONCE()
>       is required to prevent compiler mischief.  Please note that you
> -     should normally use something like rcu_dereference() instead of
> +     should normally use something like lockless_dereference() instead of

Good catch, but please keep both possibilities, something like
"... like rcu_dereference() or lockless_dereference() instead of ..."

						Thanx, Paul

>       open-coding smp_read_barrier_depends().
> 
>   (*) Overlapping loads and stores within a particular CPU will appear to be
> -- 
> 1.9.1
> 

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