From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 1/4] locking/ww_mutex: add ww_mutex_is_owned_by function v3 Date: Tue, 20 Feb 2018 15:54:13 +0100 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="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: dev@mblankhorst.nl, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org List-Id: amd-gfx.lists.freedesktop.org T24gVHVlLCBGZWIgMjAsIDIwMTggYXQgMDM6MzQ6MDdQTSArMDEwMCwgQ2hyaXN0aWFuIEvDtm5p ZyB3cm90ZToKPiA+IE9LLCBidXQgbmVpdGhlciBjYXNlIHdvdWxkIGluIGZhY3QgbmVlZCB0aGUg IWN0eCBjYXNlIHJpZ2h0PyBUaGF0J3MganVzdAo+ID4gdGhlcmUgZm9yIGNvbXBsZXRlbmVzcyBz YWtlPwo+IAo+IFVuZm9ydHVuYXRlbHkgbm90LiBUVE0gdXNlcyB0cnlsb2NrIHRvIGxvY2sgQk9z IHdoaWNoIGFyZSBhYm91dCB0byBiZQo+IGV2aWN0ZWQgdG8gbWFrZSByb29tIGZvciBhbGwgdGhl IEJPcyBsb2NrZWQgd2l0aCBhIGN0eC4KPiAKPiBJIG5lZWQgdG8gYmUgYWJsZSB0byBkaXN0aW5j dCBiZXR3ZWVuIHRoZSBCT3Mgd2hpY2ggYXJlIHRyeWxvY2tlZCBhbmQgdGhvc2UKPiB3aGljaCBh cmUgbG9ja2VkIHdpdGggYSBjdHguCj4gCj4gV3JpdGluZyB0aGlzIEkgYWN0dWFsbHkgbm90aWNl ZCB0aGUgY3VycmVudCB2ZXJzaW9uIGlzIGJ1Z2d5LCBjYXVzZSBldmVuCj4gd2hlbiB3ZSBjaGVj ayB0aGUgbXV0ZXggb3duZXIgd2Ugc3RpbGwgbmVlZCB0byBtYWtlIHN1cmUgdGhhdCB0aGUgY3R4 IGluIHRoZQo+IGxvY2sgaXMgTlVMTC4KCkh1cm0uLi4gSSBjYW4ndCByZW1lbWJlciB3aHkgdHJ5 bG9ja3MgYmVoYXZlIGxpa2UgdGhhdCwgYW5kIGl0IHNlZW1zCnJhdGhlciB1bmZvcnR1bmF0ZSAv IGluY29uc2lzdGVudC4KCkNocmlzLCBNYWFydGVuLCBkbyBlaXRoZXIgb25lIG9mIHlvdSByZW1l bWJlcj8KCkknbSB0aGlua2luZyB0aGF0IGlmIHdlIGRvIGFjcXVpcmUgdGhlIHRyeWxvY2ssIHRo ZSB0aGluZyBzaG91bGQgam9pbgp0aGUgY3R4IHN1Y2ggdGhhdCBhIHN1YnNlcXVlbnQgY29udGVu ZGluZyBtdXRleF9sb2NrKCkgY2FuIHd3IHJpZ2h0LgpfX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZlbEBs aXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1h bi9saXN0aW5mby9kcmktZGV2ZWwK 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.