From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753483AbdLUWA0 (ORCPT ); Thu, 21 Dec 2017 17:00:26 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:46580 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbdLUWAZ (ORCPT ); Thu, 21 Dec 2017 17:00:25 -0500 X-Originating-IP: 50.39.166.153 Date: Thu, 21 Dec 2017 14:00:16 -0800 From: Josh Triplett To: Ross Zwisler Cc: Matthew Wilcox , linux-kernel@vger.kernel.org, Dave Hansen , linux-mm@kvack.org, Matthew Wilcox Subject: Re: [PATCH 2/2] Introduce __cond_lock_err Message-ID: <20171221220015.GA14919@localhost> References: <20171219165823.24243-1-willy@infradead.org> <20171219165823.24243-2-willy@infradead.org> <20171221214810.GC9087@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171221214810.GC9087@linux.intel.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 21, 2017 at 02:48:10PM -0700, Ross Zwisler wrote: > On Tue, Dec 19, 2017 at 08:58:23AM -0800, Matthew Wilcox wrote: > > From: Matthew Wilcox > > > > The __cond_lock macro expects the function to return 'true' if the lock > > was acquired and 'false' if it wasn't. We have another common calling > > convention in the kernel, which is returning 0 on success and an errno > > on failure. It's hard to use the existing __cond_lock macro for those > > kinds of functions, so introduce __cond_lock_err() and convert the > > two existing users. > > This is much cleaner! One quick issue below. > > > Signed-off-by: Matthew Wilcox > > --- > > include/linux/compiler_types.h | 2 ++ > > include/linux/mm.h | 9 ++------- > > mm/memory.c | 9 ++------- > > 3 files changed, 6 insertions(+), 14 deletions(-) > > > > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > > index 6b79a9bba9a7..ff3c41c78efa 100644 > > --- a/include/linux/compiler_types.h > > +++ b/include/linux/compiler_types.h > > @@ -16,6 +16,7 @@ > > # define __acquire(x) __context__(x,1) > > # define __release(x) __context__(x,-1) > > # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) > > +# define __cond_lock_err(x,c) ((c) ? 1 : ({ __acquire(x); 0; })) > ^ > I think we actually want this to return c here ^ Then you want to use ((c) ?: ...), to avoid evaluating c twice. - Josh Triplett