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_HELO_NONE,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 60851C282CE for ; Tue, 4 Jun 2019 09:03:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 307CF24A11 for ; Tue, 4 Jun 2019 09:03:47 +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="hSXkGU4E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727068AbfFDJDp (ORCPT ); Tue, 4 Jun 2019 05:03:45 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34316 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726918AbfFDJDp (ORCPT ); Tue, 4 Jun 2019 05:03:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=Or4/2JAPsb187Uokb8j1G0UQQ7PWFIwAaNG4qlTSero=; b=hSXkGU4Eth1Uzo+CeRZUuf64v 7KAbn3S7L65x3C2i+8eMVUbE8zPK3EaLKphBrhcDB/uSOLijheaL98jKYKG/NHp8YEn/3mR+aLSVe rz+SB7rVXavRdrbUNQOCoNoUHYxw/0u5D48Hokb46ryfztQU9MzHD9Xi52d6uhc02fSEN0wdZLITN lnVho1O7RpIUrnjb9o33a0KJGdMDl7HZcLCZ04P/74UkOehIowRHaYjdn5owVAaGrAD9vVNDxs8RY qB2biiliLpF/Kv0pPu6IRqjW4ZE0/7TCDo+wNX8jT4uLBLRVCfTOe1bqRD1B4uOORThIvMLotDgxC A4A6u37EA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hY5Lb-000308-7f; Tue, 04 Jun 2019 09:03:11 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EBBF12083FE27; Tue, 4 Jun 2019 11:03:09 +0200 (CEST) Date: Tue, 4 Jun 2019 11:03:09 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH v8 14/19] locking/rwsem: Enable time-based spinning on reader-owned rwsem Message-ID: <20190604090309.GG3402@hirez.programming.kicks-ass.net> References: <20190520205918.22251-1-longman@redhat.com> <20190520205918.22251-15-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190520205918.22251-15-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 Mon, May 20, 2019 at 04:59:13PM -0400, Waiman Long wrote: > +static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem) > +{ > + long owner = atomic_long_read(&sem->owner); > + > + while (owner & RWSEM_READER_OWNED) { > + if (owner & RWSEM_NONSPINNABLE) > + break; > + owner = atomic_long_cmpxchg(&sem->owner, owner, > + owner | RWSEM_NONSPINNABLE); > + } > +} --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -206,12 +206,13 @@ static inline void rwsem_set_nonspinnabl { long owner = atomic_long_read(&sem->owner); - while (owner & RWSEM_READER_OWNED) { + do { + if (!(owner & RWSEM_READER_OWNED)) + break; if (owner & RWSEM_NONSPINNABLE) break; - owner = atomic_long_cmpxchg(&sem->owner, owner, - owner | RWSEM_NONSPINNABLE); - } + } while (!atomic_long_try_cmpxchg(&sem->owner, &owner, + owner | RWSEM_NONSPINNABLE)); } /*