From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH] locking/qrwlock: Let qrwlock has same layout regardless of the endian Date: Wed, 15 Jun 2016 10:20:51 +0100 Message-ID: <20160615092051.GC24029@arm.com> References: <1465982177-2949-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from foss.arm.com ([217.140.101.70]:35629 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529AbcFOJUz (ORCPT ); Wed, 15 Jun 2016 05:20:55 -0400 Content-Disposition: inline In-Reply-To: <1465982177-2949-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Pan Xinhui Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, ingo@redhat.com, peterz@infradead.org, arnd@arndb.de, Waiman.Long@hpe.com On Wed, Jun 15, 2016 at 05:16:17PM +0800, Pan Xinhui wrote: > This patch aims to get rid of endianness in queued_write_unlock(). We > want to set __qrwlock->wmode to NULL, however the address is not > &lock->cnts in big endian machine. That causes queued_write_unlock() > write NULL to the wrong field of __qrwlock. > > Actually qrwlock can have same layout, IOW we can remove the #if > __little_endian in struct __qrwlock. With such modification, we only > need define some _QW* and _QR* with corresponding values in different > endian systems. > > Suggested-by: Will Deacon > Signed-off-by: Pan Xinhui > --- > include/asm-generic/qrwlock.h | 15 +++++++++++---- > kernel/locking/qrwlock.c | 10 ++++------ > 2 files changed, 15 insertions(+), 10 deletions(-) > > diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h > index 54a8e65..b135c11 100644 > --- a/include/asm-generic/qrwlock.h > +++ b/include/asm-generic/qrwlock.h > @@ -27,11 +27,18 @@ > /* > * Writer states & reader shift and bias > */ > -#define _QW_WAITING 1 /* A writer is waiting */ > -#define _QW_LOCKED 0xff /* A writer holds the lock */ > -#define _QW_WMASK 0xff /* Writer mask */ > +#ifdef __LITTLE_ENDIAN > #define _QR_SHIFT 8 /* Reader count shift */ > -#define _QR_BIAS (1U << _QR_SHIFT) > +#define _QW_SHIFF 0 /* Writer mode shift */ Well, there are other typos that could've been worse, but you probably want to fix this... Will