From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753674AbdLUWK4 (ORCPT ); Thu, 21 Dec 2017 17:10:56 -0500 Received: from mga04.intel.com ([192.55.52.120]:65061 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750881AbdLUWKw (ORCPT ); Thu, 21 Dec 2017 17:10:52 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,437,1508828400"; d="scan'208";a="18013940" Date: Thu, 21 Dec 2017 15:10:50 -0700 From: Ross Zwisler To: Josh Triplett Cc: Ross Zwisler , 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: <20171221221050.GD9087@linux.intel.com> References: <20171219165823.24243-1-willy@infradead.org> <20171219165823.24243-2-willy@infradead.org> <20171221214810.GC9087@linux.intel.com> <20171221220015.GA14919@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171221220015.GA14919@localhost> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 21, 2017 at 02:00:16PM -0800, Josh Triplett wrote: > 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. Oh, yep, great catch.