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 0BD12C10F13 for ; Thu, 11 Apr 2019 08:12:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9A5E20873 for ; Thu, 11 Apr 2019 08:12:44 +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="Nn+R0jOv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726682AbfDKIMn (ORCPT ); Thu, 11 Apr 2019 04:12:43 -0400 Received: from merlin.infradead.org ([205.233.59.134]:32934 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbfDKIMn (ORCPT ); Thu, 11 Apr 2019 04:12:43 -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=+Wb+8kDvOTlNP0v2y55MV3piIexTa+9FKS9+7edDCGE=; b=Nn+R0jOvISCE6gcqwEQXdfzDG Lg6jiuX2huUH+4WE/N1ncAGaU5Merd6ByA4KMCK2+q4ZNmkEKZ+XHds8pk4u4pQIjEGhZprFCmWxs odG97uDtlJYE3/uc8WekvR0PxgltJtU0IAxIztAJHhxkLk+cbj4HulS9U2AlmHnEH7fVhaPWz3avn tAi4k6ZtFXRE6FwCdb2WFs56gdInsCYwvqUUkzkSoTyWFSsjFPSJpSRSnDkqd6445j96oPoaHQywL qaphlFncrC8CotaAh/f+TCpF+oNGvsoum+TiFR3nrfsXlAeoxmj1zXlJ/SX8yiAiDEzIQ6W9Ck3Bc VStixML1w==; 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 1hEUot-00086s-82; Thu, 11 Apr 2019 08:12:27 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 802A129AA8DC4; Thu, 11 Apr 2019 10:12:24 +0200 (CEST) Date: Thu, 11 Apr 2019 10:12:24 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH-tip v3 02/14] locking/rwsem: Make owner available even if !CONFIG_RWSEM_SPIN_ON_OWNER Message-ID: <20190411081224.GB4038@hirez.programming.kicks-ass.net> References: <20190410184231.6748-1-longman@redhat.com> <20190410184231.6748-3-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190410184231.6748-3-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 Wed, Apr 10, 2019 at 02:42:19PM -0400, Waiman Long wrote: > The owner field in the rw_semaphore structure is used primarily for > optimistic spinning. However, identifying the rwsem owner can also be > helpful in debugging as well as tracing locking related issues when > analyzing crash dump. The owner field may also store state information > that can be important to the operation of the rwsem. > > So the owner field is now made a permanent member of the rw_semaphore > structure irrespective of CONFIG_RWSEM_SPIN_ON_OWNER. sem->owner is still initialized under CONFIG_RWSEM_SPIN_ON_OWNER.