From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 1/3] locking/ww_mutex: cleanup lock->ctx usage in amdgpu Date: Tue, 20 Feb 2018 13:35:32 +0100 Message-ID: <20180220123532.GD25314@hirez.programming.kicks-ass.net> References: <20180215141944.4332-1-christian.koenig@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20180215141944.4332-1-christian.koenig@amd.com> 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: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org List-Id: amd-gfx.lists.freedesktop.org ClRoaXMgcmVhbGx5IHNob3VsZCd2ZSBiZWVuIENjJ2VkIHRvIG1lLgoKT24gVGh1LCBGZWIgMTUs IDIwMTggYXQgMDM6MTk6NDJQTSArMDEwMCwgQ2hyaXN0aWFuIEvDtm5pZyB3cm90ZToKPiBkaWZm IC0tZ2l0IGEvaW5jbHVkZS9saW51eC93d19tdXRleC5oIGIvaW5jbHVkZS9saW51eC93d19tdXRl eC5oCj4gaW5kZXggMzlmZGExOTViZjc4Li5kZDU4MGRiMjg5ZTggMTAwNjQ0Cj4gLS0tIGEvaW5j bHVkZS9saW51eC93d19tdXRleC5oCj4gKysrIGIvaW5jbHVkZS9saW51eC93d19tdXRleC5oCj4g QEAgLTM1OCw0ICszNTgsMjEgQEAgc3RhdGljIGlubGluZSBib29sIHd3X211dGV4X2lzX2xvY2tl ZChzdHJ1Y3Qgd3dfbXV0ZXggKmxvY2spCj4gIAlyZXR1cm4gbXV0ZXhfaXNfbG9ja2VkKCZsb2Nr LT5iYXNlKTsKPiAgfQo+ICAKPiArLyoqCj4gKyAqIHd3X211dGV4X2lzX293bmVkX2J5IC0gaXMg dGhlIHcvdyBtdXRleCBsb2NrZWQgYnkgdGhpcyB0YXNrIGluIHRoYXQgY29udGV4dAo+ICsgKiBA bG9jazogdGhlIG11dGV4IHRvIGJlIHF1ZXJpZWQKPiArICogQHRhc2s6IHRoZSB0YXNrIHN0cnVj dHVyZSB0byBjaGVjawo+ICsgKiBAY3R4OiB0aGUgdy93IGFjcXVpcmUgY29udGV4dCB0byB0ZXN0 Cj4gKyAqCj4gKyAqIFJldHVybnMgdHJ1ZSBpZiB0aGUgbXV0ZXggaXMgbG9ja2VkIGluIHRoZSBj b250ZXh0IGJ5IHRoZSBnaXZlbiB0YXNrLCBmYWxzZQo+ICsgKiBvdGhlcndpc2UuCj4gKyAqLwo+ ICtzdGF0aWMgaW5saW5lIGJvb2wgd3dfbXV0ZXhfaXNfb3duZWRfYnkoc3RydWN0IHd3X211dGV4 ICpsb2NrLAo+ICsJCQkJCXN0cnVjdCB0YXNrX3N0cnVjdCAqdGFzaywKPiArCQkJCQlzdHJ1Y3Qg d3dfYWNxdWlyZV9jdHggKmN0eCkKPiArewo+ICsJcmV0dXJuIGxpa2VseShfX211dGV4X293bmVy KCZsb2NrLT5iYXNlKSA9PSB0YXNrKSAmJgo+ICsJCVJFQURfT05DRShsb2NrLT5jdHgpID09IGN0 eDsKPiArfQoKTmFrIG9uIHRoYXQgaW50ZXJmYWNlLCB0aGF0J3MgcmFjeSBhbmQgYnJva2VuIGJ5 IGRlc2lnbi4KCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f CmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpo dHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752391AbeBTNEN (ORCPT ); Tue, 20 Feb 2018 08:04:13 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:46534 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752097AbeBTNCI (ORCPT ); Tue, 20 Feb 2018 08:02:08 -0500 Date: Tue, 20 Feb 2018 13:35:32 +0100 From: Peter Zijlstra To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] locking/ww_mutex: cleanup lock->ctx usage in amdgpu Message-ID: <20180220123532.GD25314@hirez.programming.kicks-ass.net> References: <20180215141944.4332-1-christian.koenig@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180215141944.4332-1-christian.koenig@amd.com> 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 This really should've been Cc'ed to me. On Thu, Feb 15, 2018 at 03:19:42PM +0100, Christian König wrote: > diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h > index 39fda195bf78..dd580db289e8 100644 > --- a/include/linux/ww_mutex.h > +++ b/include/linux/ww_mutex.h > @@ -358,4 +358,21 @@ static inline bool ww_mutex_is_locked(struct ww_mutex *lock) > return mutex_is_locked(&lock->base); > } > > +/** > + * ww_mutex_is_owned_by - is the w/w mutex locked by this task in that context > + * @lock: the mutex to be queried > + * @task: the task structure to check > + * @ctx: the w/w acquire context to test > + * > + * Returns true if the mutex is locked in the context by the given task, false > + * otherwise. > + */ > +static inline bool ww_mutex_is_owned_by(struct ww_mutex *lock, > + struct task_struct *task, > + struct ww_acquire_ctx *ctx) > +{ > + return likely(__mutex_owner(&lock->base) == task) && > + READ_ONCE(lock->ctx) == ctx; > +} Nak on that interface, that's racy and broken by design.