linux-kernel - Re: [RFC][PATCH v3]: documentation,atomic: Add new documents

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Message-ID: <20170726124750.vktrn5zi2gmpzfru@tardis>
Date:   Wed, 26 Jul 2017 20:47:50 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Will Deacon <will.deacon@....com>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [RFC][PATCH v3]: documentation,atomic: Add new documents

On Wed, Jul 26, 2017 at 01:53:28PM +0200, Peter Zijlstra wrote:
> 
> New version..
> 
> 
> ---
> Subject: documentation,atomic: Add new documents
> From: Peter Zijlstra <peterz@...radead.org>
> Date: Mon Jun 12 14:50:27 CEST 2017
> 
> Since we've vastly expanded the atomic_t interface in recent years the
> existing documentation is woefully out of date and people seem to get
> confused a bit.
> 
> Start a new document to hopefully better explain the current state of
> affairs.
> 
> The old atomic_ops.txt also covers bitmaps and a few more details so
> this is not a full replacement and we'll therefore keep that document
> around until such a time that we've managed to write more text to cover
> its entire.
> 

You seems have a unfinished paragraph..

> Also please, ReST people, go away.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
[...]
> +
> +Further, while something like:
> +
> +  smp_mb__before_atomic();
> +  atomic_dec(&X);
> +
> +is a 'typical' RELEASE pattern, the barrier is strictly stronger than
> +a RELEASE. Similarly for something like:
> +

.. at here. Maybe you planned to put stronger ACQUIRE pattern?

> +
> --- a/Documentation/memory-barriers.txt
> +++ b/Documentation/memory-barriers.txt
> @@ -498,7 +498,7 @@ VARIETIES OF MEMORY BARRIER
>       This means that ACQUIRE acts as a minimal "acquire" operation and
>       RELEASE acts as a minimal "release" operation.
>  
[...]
> -
> -[!] Note that special memory barrier primitives are available for these
> -situations because on some CPUs the atomic instructions used imply full memory
> -barriers, and so barrier instructions are superfluous in conjunction with them,
> -and in such cases the special barrier primitives will be no-ops.
> -
> -See Documentation/core-api/atomic_ops.rst for more information.
> +See Documentation/atomic_t.txt for more information.
>  

s/atomic_t.txt/atomic_{t,bitops}.txt/ ?

other than those two tiny things,

Reviewed-by: Boqun Feng <boqun.feng@...il.com>

Regards,
Boqun

>  
>  ACCESSING DEVICES

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