From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF393C282CC for ; Thu, 7 Feb 2019 19:37:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD5E42175B for ; Thu, 7 Feb 2019 19:37:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bP26+sXr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727070AbfBGThQ (ORCPT ); Thu, 7 Feb 2019 14:37:16 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:35378 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726824AbfBGThP (ORCPT ); Thu, 7 Feb 2019 14:37:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=XyuH3s5btQ7mHAGeF3ZoeE02Akb0cMxexPWpqxP67uA=; b=bP26+sXr54fuUiR9IiKuknojR 05eeVLzShuE8V2JQQq+lfq9ZtSMoU0jIpnXpvfH4ZhsSvLea4l2sSH5NKBTpsbQLAV7Al75giSjt4 8D/9lUqRmMfG9pqGPFyQe/+x1Wm5DqeO1ii498wxhKnVW3wXrlqtwMhwxrSd74jTQ7PfXWkiAJd2s WZXsHWFftOJha3iNy6AqDdu4EriyGPQIuAx1ekfM1n367vAWmnMagMW/lyFtWJcMQKZFSwevsBhJA MnCmBTgT3RNgZ/zdgpD5R/Ww9xF1HBKd1/4p5r2Bs4+dBP5QTBcUXQNetp4Lp4dJEaqxfwTLblQ+a XoUnvxP+Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1grpTn-0007db-3V; Thu, 07 Feb 2019 19:36:59 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8E1222029E062; Thu, 7 Feb 2019 20:36:56 +0100 (CET) Date: Thu, 7 Feb 2019 20:36:56 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, x86@kernel.org, Arnd Bergmann , Borislav Petkov , "H. Peter Anvin" , Davidlohr Bueso , Linus Torvalds , Andrew Morton , Tim Chen Subject: Re: [PATCH-tip 04/22] locking/rwsem: Remove arch specific rwsem files Message-ID: <20190207193656.GF32511@hirez.programming.kicks-ass.net> References: <1549566446-27967-1-git-send-email-longman@redhat.com> <1549566446-27967-5-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1549566446-27967-5-git-send-email-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 07, 2019 at 02:07:08PM -0500, Waiman Long wrote: > +static inline int __down_read_trylock(struct rw_semaphore *sem) > +{ > + long tmp; > + > + while ((tmp = atomic_long_read(&sem->count)) >= 0) { > + if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp, > + tmp + RWSEM_ACTIVE_READ_BIAS)) { > + return 1; > + } > + } Nah, you're supposed to write that like: for (;;) { val = atomic_long_cond_read_relaxed(&sem->count, VAL < 0); if (atomic_long_try_cmpxchg_acquire(&sem->count, &val, val + RWSEM_ACTIVE_READ_BIAS)) break; } > + return 0; > +} Anyway, yuck, you're keeping all that BIAS nonsense :/ I was so hoping for a rwsem implementation without that impenetrable crap.