From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756028AbZBFWkZ (ORCPT ); Fri, 6 Feb 2009 17:40:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751986AbZBFWkM (ORCPT ); Fri, 6 Feb 2009 17:40:12 -0500 Received: from relay.gothnet.se ([82.193.160.251]:64514 "EHLO GOTHNET-SMTP2.gothnet.se" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750831AbZBFWkL convert rfc822-to-8bit (ORCPT ); Fri, 6 Feb 2009 17:40:11 -0500 Message-ID: <498CBC3B.6010609@shipmail.org> Date: Fri, 06 Feb 2009 23:39:55 +0100 From: =?ISO-8859-15?Q?Thomas_Hellstr=F6m?= User-Agent: Thunderbird 2.0.0.18 (X11/20081120) MIME-Version: 1.0 To: Jesse Barnes CC: Eric Anholt , DRI , Linux Kernel Subject: Re: Gem GTT mmaps.. References: <498A1760.7010108@shipmail.org> <200902060914.59956.jbarnes@virtuousgeek.org> <498CAD2F.5070806@shipmail.org> <200902061424.02906.jbarnes@virtuousgeek.org> In-Reply-To: <200902061424.02906.jbarnes@virtuousgeek.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed X-BitDefender-Scanner: Mail not scanned due to license constraints Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jesse Barnes wrote: > On Friday, February 6, 2009 1:35 pm Thomas Hellström wrote: > >> Jesse Barnes wrote: >> >>> On Thursday, February 5, 2009 10:37 am Jesse Barnes wrote: >>> >>>> So if we leave the lookup reference around from the GTT mapping ioctl, >>>> that would take care of new mappings. And if we added/removed >>>> references at VM open/close time, we should be covered for fork. But is >>>> it ok to add a new unref in the finish ioctl for GTT mapped objects? I >>>> don't think so, because we don't know for sure if the caller was the one >>>> that created the new fake offset (which would be one way of detecting >>>> whether it was GTT mapped). Seems like we need a new unmap ioctl? Or we >>>> could put the mapping ref/unref in libdrm, where it would be tracked on >>>> a per-process basis... >>>> >>> Ah but maybe we should just tear down the fake offset at unmap time; then >>> we'd be able to use it as an existence test for the mapping and get the >>> refcounting right. The last thing I thought of was whether we'd be ok in >>> a map_gtt -> crash case. I *think* the vm_close code will deal with >>> that, if we do a deref there? >>> >> Yes, an mmap() is always paired with a vm_close(), and the vm_close() >> also happens in a crash situation. >> > > This one should cover the cases you found. > - ref at map time will keep the object around so fault shouldn't fail > - additional threads will take their refs in vm_open/close > - unmap will unref and remove mmap_offset allowing object to be freed > > Jesse, Yes, it looks OK to me. A short question, though, when is i915_gem_sw_finish_ioctl called? Is it possible that the client may still think its mmap offset is valid? Thomas