From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751249AbdBTWit (ORCPT <rfc822;w@1wt.eu>);
        Mon, 20 Feb 2017 17:38:49 -0500
Received: from mail-wr0-f196.google.com ([209.85.128.196]:33518 "EHLO
        mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1750981AbdBTWis (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 20 Feb 2017 17:38:48 -0500
Date: Mon, 20 Feb 2017 23:38:44 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@us.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] locking changes for v4.11
Message-ID: <20170220223844.GA12642@gmail.com>
References: <20170220095420.GA17198@gmail.com>
 <CA+55aFwVYhWuAaQdU97k2Ru5q4DR7Hzo8aNmDsovFpWwJGSgmw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+55aFwVYhWuAaQdU97k2Ru5q4DR7Hzo8aNmDsovFpWwJGSgmw@mail.gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Feb 20, 2017 at 1:54 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> >  - Implement wraparound-safe refcount_t and kref_t types based on generic atomic
> >    primitives (Peter Zijlstra)
> 
> Ugh. This apparently never got the uninlining fixes?

Yeah, will fix it ASAP!

> I've pulled it, but I still don't like the inlining. Particularly with
> CONFIG_DEBUG_REFCOUNT it generates obnnoxious code, but even without
> the debugging there's just no point in it.
> 
> Being inlined also means that architectures cannot optimize it, which
> is sad. If you have a LL/SC model for atomics, then using
> atomic_cmpxchg_relaxed() for the refcounting is just too stupid for
> words.
> 
> So I continue to think this code should
> 
>  (a) be in lib/refcount.c, with just the declarations in the header
> file (oh, keep the "set" and "read" functions inline by all means)
> 
>  (b) be marked __weak, so that architectures like ARM/PPC can decide
> to do their own improved implementations.

Yeah, agreed, will do.

> But as mentioned, it's in my tree as-is now and going through the build test.

Thanks!

	Ingo