From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751827AbeBTOyZ (ORCPT ); Tue, 20 Feb 2018 09:54:25 -0500 Received: from merlin.infradead.org ([205.233.59.134]:56290 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbeBTOyY (ORCPT ); Tue, 20 Feb 2018 09:54:24 -0500 Date: Tue, 20 Feb 2018 15:54:13 +0100 From: Peter Zijlstra To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, dev@mblankhorst.nl, chris@chris-wilson.co.uk Subject: Re: [PATCH 1/4] locking/ww_mutex: add ww_mutex_is_owned_by function v3 Message-ID: <20180220145413.GF25201@hirez.programming.kicks-ass.net> References: <20180220125829.27060-1-christian.koenig@amd.com> <20180220131253.GF25314@hirez.programming.kicks-ass.net> <8fd80334-4d0e-8ed0-8a09-02a7e36a0eae@gmail.com> <20180220135709.GD25201@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 20, 2018 at 03:34:07PM +0100, Christian König wrote: > > OK, but neither case would in fact need the !ctx case right? That's just > > there for completeness sake? > > Unfortunately not. TTM uses trylock to lock BOs which are about to be > evicted to make room for all the BOs locked with a ctx. > > I need to be able to distinct between the BOs which are trylocked and those > which are locked with a ctx. > > Writing this I actually noticed the current version is buggy, cause even > when we check the mutex owner we still need to make sure that the ctx in the > lock is NULL. Hurm... I can't remember why trylocks behave like that, and it seems rather unfortunate / inconsistent. Chris, Maarten, do either one of you remember? I'm thinking that if we do acquire the trylock, the thing should join the ctx such that a subsequent contending mutex_lock() can ww right.