From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [PATCH] drm/i915: Check the timeout passed to i915_wait_request Date: Tue, 01 Dec 2015 11:04:15 +0200 Message-ID: <87oaea5yls.fsf@intel.com> References: <1448544702-5594-1-git-send-email-chris@chris-wilson.co.uk> <20151126144900.GT17050@phenom.ffwll.local> <20151126160655.GN23362@nuc-i3427.alporthouse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTP id 6D9696E5D9 for ; Tue, 1 Dec 2015 01:00:12 -0800 (PST) In-Reply-To: <20151126160655.GN23362@nuc-i3427.alporthouse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Chris Wilson , Daniel Vetter Cc: Lionel Landwerlin , Daniel Vetter , intel-gfx@lists.freedesktop.org, stable@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org T24gVGh1LCAyNiBOb3YgMjAxNSwgQ2hyaXMgV2lsc29uIDxjaHJpc0BjaHJpcy13aWxzb24uY28u dWs+IHdyb3RlOgo+IE9uIFRodSwgTm92IDI2LCAyMDE1IGF0IDAzOjQ5OjAwUE0gKzAxMDAsIERh bmllbCBWZXR0ZXIgd3JvdGU6Cj4+IE9uIFRodSwgTm92IDI2LCAyMDE1IGF0IDAxOjMxOjQyUE0g KzAwMDAsIENocmlzIFdpbHNvbiB3cm90ZToKPj4gPiBXZSBoYXZlIHJlbGllZCB1cG9uIHRoZSBz b2xlIGNhbGxlciAod2FpdF9pb2N0bCkgdmFsaWRhdGluZyB0aGUgdGltZW91dAo+PiA+IGFyZ3Vt ZW50LiBIb3dldmVyLCB3aGVuIHdhaXRpbmcgZm9yIG11bHRpcGxlIHJlcXVlc3RzIEkgZm9yZ290 IHRvIGVuc3VyZQo+PiA+IHRoYXQgdGhlIHRpbWVvdXQgd2FzIHN0aWxsIHBvc2l0aXZlIG9uIHRo ZSBsYXRlciByZXF1ZXN0cy4gVGhpcyBpcyBtb3JlCj4+ID4gc2ltcGx5IGRvbmUgaW5zaWRlIF9f aTkxNV93YWl0X3JlcXVlc3QuCj4+ID4gCj4+ID4gRml4ZXMgcmVncmVzc2lvbiBpbnRyb2R1Y2Vk IGluCj4+ID4gY29tbWl0IGI0NzE2MTg1OGJhMTNjOWM3ZTAzMzMzMTMyMjMwZDY2ZTAwOGRkNTUK Pj4gPiBBdXRob3I6IENocmlzIFdpbHNvbiA8Y2hyaXNAY2hyaXMtd2lsc29uLmNvLnVrPgo+PiA+ IERhdGU6ICAgTW9uIEFwciAyNyAxMzo0MToxNyAyMDE1ICswMTAwCj4+ID4gCj4+ID4gICAgIGRy bS9pOTE1OiBJbXBsZW1lbnQgaW50ZXItZW5naW5lIHJlYWQtcmVhZCBvcHRpbWlzYXRpb25zCj4+ ID4gCj4+ID4gU2lnbmVkLW9mZi1ieTogQ2hyaXMgV2lsc29uIDxjaHJpc0BjaHJpcy13aWxzb24u Y28udWs+Cj4+ID4gQ2M6IExpb25lbCBMYW5kd2VybGluIDxsaW9uZWwuZy5sYW5kd2VybGluQGxp bnV4LmludGVsLmNvbT4KPj4gPiBDYzogVHZydGtvIFVyc3VsaW4gPHR2cnRrby51cnN1bGluQGlu dGVsLmNvbT4KPj4gPiBDYzogRGFuaWVsIFZldHRlciA8ZGFuaWVsLnZldHRlckBmZndsbC5jaD4K Pj4gPiBDYzogc3RhYmxlQHZnZXIua2VybmVsLm9yZwo+PiAKPj4gQ29tbWl0IG1lc3NhZ2Ugc2hv dWxkIGV4cGxhaW4gd2hhdCB0aGUgYWN0dWFsIHByb2JsZW0gaXMgLSB3ZSBhZGQgMSBqaWZmeQo+ PiBvZiBkZWxheSBmb3IgZWFjaCB3YWl0X3JlcXVlc3QsIHBvdGVudGlhbGx5IHdhaXRpbmcgcXVp dGUgYSBiaXQgbG9uZ2VyCj4+IHRoYW4gd2hhdCB1c2Vyc3BhY2UgYXNrZWQgZm9yLgo+PiAKPj4g QW5kIG5vdCBzdXJlIHRoaXMgcmVhbGx5IGp1c3RpZmllcyBmb3IgY2M6IHN0YWJsZSwgc2luY2Ug YWxsIHRoZSB3YWl0Cj4+IHN5c2NhbGxzIHJlc2VydmUgdGhlIHJpZ2h0IHRvIHdhaXQgbG9uZ2Vy LiBPZiBjb3Vyc2Ugd2Ugc2hvdWxkIGZpeCBpdCwKPj4ganVzdCB0byBrZWVwIHZhbGlkYXRpbmcg dGhpcyBwb3NzaWJsZS4KPgo+IERyb3BwaW5nIHN0YWJsZSBpcyBmaW5lLCB0aGF0IHdhcyBqdXN0 IGEga25lZSBqZXJrIHJlYWN0aW9uIHRvIGZpbmRpbmcgYQo+IHJlZ3Jlc3Npb24uIFRoZSBpbXBh Y3QgaXMgMSBqaWZmaWUgZm9yIGVhY2ggZXh0cmEgYWN0aXZlIHJpbmcgZm9yIGEKPiB3YWl0X2lv Y3RsIHdpdGggYSB0aW1lb3V0IC0tIEkgZG9uJ3QgdGhpbmsgYW55b25lIGhhcyBub3RpY2VkLgoK UHVzaGVkIHRvIGRybS1pbnRlbC1maXhlcyB3aXRoIHNvbWUgcmFuZG9tIGNvcHktcGFzdGUgYWRk ZWQgYWJvdXQgdGhlIDEKamlmZnkuIFRoYW5rcyBmb3IgdGhlIHBhdGNoIGFuZCByZXZpZXcuCgpC UiwKSmFuaS4KCgotLSAKSmFuaSBOaWt1bGEsIEludGVsIE9wZW4gU291cmNlIFRlY2hub2xvZ3kg Q2VudGVyCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCklu dGVsLWdmeCBtYWlsaW5nIGxpc3QKSW50ZWwtZ2Z4QGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRw Oi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vaW50ZWwtZ2Z4Cg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com ([192.55.52.93]:14116 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755794AbbLAJAI (ORCPT ); Tue, 1 Dec 2015 04:00:08 -0500 From: Jani Nikula To: Chris Wilson , Daniel Vetter Cc: Lionel Landwerlin , Daniel Vetter , intel-gfx@lists.freedesktop.org, stable@vger.kernel.org Subject: Re: [Intel-gfx] [PATCH] drm/i915: Check the timeout passed to i915_wait_request In-Reply-To: <20151126160655.GN23362@nuc-i3427.alporthouse.com> References: <1448544702-5594-1-git-send-email-chris@chris-wilson.co.uk> <20151126144900.GT17050@phenom.ffwll.local> <20151126160655.GN23362@nuc-i3427.alporthouse.com> Date: Tue, 01 Dec 2015 11:04:15 +0200 Message-ID: <87oaea5yls.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: stable-owner@vger.kernel.org List-ID: On Thu, 26 Nov 2015, Chris Wilson wrote: > On Thu, Nov 26, 2015 at 03:49:00PM +0100, Daniel Vetter wrote: >> On Thu, Nov 26, 2015 at 01:31:42PM +0000, Chris Wilson wrote: >> > We have relied upon the sole caller (wait_ioctl) validating the timeout >> > argument. However, when waiting for multiple requests I forgot to ensure >> > that the timeout was still positive on the later requests. This is more >> > simply done inside __i915_wait_request. >> > >> > Fixes regression introduced in >> > commit b47161858ba13c9c7e03333132230d66e008dd55 >> > Author: Chris Wilson >> > Date: Mon Apr 27 13:41:17 2015 +0100 >> > >> > drm/i915: Implement inter-engine read-read optimisations >> > >> > Signed-off-by: Chris Wilson >> > Cc: Lionel Landwerlin >> > Cc: Tvrtko Ursulin >> > Cc: Daniel Vetter >> > Cc: stable@vger.kernel.org >> >> Commit message should explain what the actual problem is - we add 1 jiffy >> of delay for each wait_request, potentially waiting quite a bit longer >> than what userspace asked for. >> >> And not sure this really justifies for cc: stable, since all the wait >> syscalls reserve the right to wait longer. Of course we should fix it, >> just to keep validating this possible. > > Dropping stable is fine, that was just a knee jerk reaction to finding a > regression. The impact is 1 jiffie for each extra active ring for a > wait_ioctl with a timeout -- I don't think anyone has noticed. Pushed to drm-intel-fixes with some random copy-paste added about the 1 jiffy. Thanks for the patch and review. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center