From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Date: Wed, 20 Apr 2016 21:36:37 +0000 Subject: Re: [PATCH 10/11] x86, rwsem: provide __down_write_killable Message-Id: <20160420213637.GA4978@pd.tnic> List-Id: References: <1460041951-22347-11-git-send-email-mhocko@kernel.org> <20160413090829.GB29579@gmail.com> <20160413091625.GF14351@dhcp22.suse.cz> <20160413091943.GA17858@gmail.com> <20160413102731.GA29896@gmail.com> <20160413124943.GH14351@dhcp22.suse.cz> <20160420134019.GX3448@twins.programming.kicks-ass.net> <91A11395-ACAA-4043-B770-2DF6CBAED54C@zytor.com> <20160420204501.GA6815@pd.tnic> <5717EF59.1030709@zytor.com> In-Reply-To: <5717EF59.1030709@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "H. Peter Anvin" Cc: Peter Zijlstra , Michal Hocko , Ingo Molnar , LKML , Ingo Molnar , Thomas Gleixner , "David S. Miller" , Tony Luck , Andrew Morton , Chris Zankel , Max Filippov , x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, Josh Poimboeuf On Wed, Apr 20, 2016 at 02:06:33PM -0700, H. Peter Anvin wrote: > Setting ret to sem doesn't make any sense. Just use "=a" and "a". Yeah, that's what Michal's patch ontop does. And to answer my own question: we need the "a" (sem) input for the fast path. I guess we can still move "1" (RWSEM_ACTIVE_WRITE_BIAS) before the asm(): long tmp = RWSEM_ACTIVE_WRITE_BIAS; One thing I'm still not clear on is why we need the output tmp operand: "=d" (tmp) ? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751761AbcDTVhD (ORCPT ); Wed, 20 Apr 2016 17:37:03 -0400 Received: from mail.skyhub.de ([78.46.96.112]:52320 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751069AbcDTVg6 (ORCPT ); Wed, 20 Apr 2016 17:36:58 -0400 Date: Wed, 20 Apr 2016 23:36:37 +0200 From: Borislav Petkov To: "H. Peter Anvin" Cc: Peter Zijlstra , Michal Hocko , Ingo Molnar , LKML , Ingo Molnar , Thomas Gleixner , "David S. Miller" , Tony Luck , Andrew Morton , Chris Zankel , Max Filippov , x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, Josh Poimboeuf Subject: Re: [PATCH 10/11] x86, rwsem: provide __down_write_killable Message-ID: <20160420213637.GA4978@pd.tnic> References: <1460041951-22347-11-git-send-email-mhocko@kernel.org> <20160413090829.GB29579@gmail.com> <20160413091625.GF14351@dhcp22.suse.cz> <20160413091943.GA17858@gmail.com> <20160413102731.GA29896@gmail.com> <20160413124943.GH14351@dhcp22.suse.cz> <20160420134019.GX3448@twins.programming.kicks-ass.net> <91A11395-ACAA-4043-B770-2DF6CBAED54C@zytor.com> <20160420204501.GA6815@pd.tnic> <5717EF59.1030709@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5717EF59.1030709@zytor.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 20, 2016 at 02:06:33PM -0700, H. Peter Anvin wrote: > Setting ret to sem doesn't make any sense. Just use "=a" and "a". Yeah, that's what Michal's patch ontop does. And to answer my own question: we need the "a" (sem) input for the fast path. I guess we can still move "1" (RWSEM_ACTIVE_WRITE_BIAS) before the asm(): long tmp = RWSEM_ACTIVE_WRITE_BIAS; One thing I'm still not clear on is why we need the output tmp operand: "=d" (tmp) ? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.