From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758054AbcHYURd (ORCPT ); Thu, 25 Aug 2016 16:17:33 -0400 Received: from mail-sn1nam02on0104.outbound.protection.outlook.com ([104.47.36.104]:13856 "EHLO NAM02-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757202AbcHYUR3 (ORCPT ); Thu, 25 Aug 2016 16:17:29 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=waiman.long@hpe.com; Message-ID: <57BF4E2E.2020406@hpe.com> Date: Thu, 25 Aug 2016 15:59:42 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Daniel Vetter CC: Peter Zijlstra , Linus Torvalds , Jason Low , "Ding Tianhong" , Thomas Gleixner , Will Deacon , Ingo Molnar , Imre Deak , Linux Kernel Mailing List , Davidlohr Bueso , Tim Chen , Terry Rudd , "Paul E. McKenney" , Jason Low , Chris Wilson Subject: Re: [RFC][PATCH -v2 1/4] locking/drm/i915: Kill mutex trickery References: <20160825183734.113736626@infradead.org> <20160825184324.713134633@infradead.org> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [72.71.243.247] X-ClientProxiedBy: MWHPR07CA0023.namprd07.prod.outlook.com (10.172.94.33) To CS1PR84MB0312.NAMPRD84.PROD.OUTLOOK.COM (10.162.190.30) X-MS-Office365-Filtering-Correlation-Id: 8a570cd8-01bb-4e0d-2e81-08d3cd2260f4 X-Microsoft-Exchange-Diagnostics: 1;CS1PR84MB0312;2:Zys/qrFQKynavge9LiV00nYgmQA38OlcvT12vuvrHusIEGLIxI977bGz/joP7zZBUcCQJoiAJuJ9NxqwhbZNxuc3gTINoZB8iRbevxIzVDqbDO/X7Mr5iN+5W/7tgWmfWqJBO6aMxyagpHkbltImfcJM9PR9C4a0qo/yrs0LTQJkt4oGnrb5SgEd2yjS2ST6;3:4MuEykA2t8LaIkdVMYL/YEURC/wMzoto6rI+AO3HSFeonl7fxXd2zP8JVHY1gWdA5zP6kLCe9BC2JdCmm9gmWKL1kYT5q8ujKEoN1Auu4PcPposzCbQXqe39qSphCKQQ X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:CS1PR84MB0312; X-Microsoft-Exchange-Diagnostics: 1;CS1PR84MB0312;25: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 X-Microsoft-Exchange-Diagnostics: 1;CS1PR84MB0312;31:xhl6IJwVYzIvEf1+GaUKS3vf9vc887UYyVpu7F1FV2ISA8YoJ4MPaziKDfNodHQrBneFqipKqX9hRwPagRXDvN7YjahyYNUT5YBe7W+R+Mr5jn6tHDDEyvnlxwsjePvX0nYQSArwJImeYu8yVb99/X1zNPtpEjq+LREkiEsMkvFcZ2n54BuQlUpF3Idh5npbgKa+7E34XzD4RZ1EO3uWaIlFqXx3EvalHjqv94TFaqw=;20: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 X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:(788757137089); 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Since I'm going to change the >> implementation this will break, take it out. >> >> Cc: Chris Wilson >> Cc: Daniel Vetter >> Signed-off-by: Peter Zijlstra (Intel) > It's horrible, but we die without this in spurious oom. And we haven't > made much progress in recent years to throw out the locking scheme and > replace it by something else that doesn't need a recursive mutex. > > But initerim I guess we could set our own owner field and check that > to keep the duct-tape from getting off completely. > -Daniel Another alternative is to provide a standard mutex API that returns the owner of the lock if there is a real need for this capability. Peeking into lock internal is not a good practice. Cheers, Longman