From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967350AbdDSVN6 (ORCPT ); Wed, 19 Apr 2017 17:13:58 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40505 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S967229AbdDSVN4 (ORCPT ); Wed, 19 Apr 2017 17:13:56 -0400 Subject: Re: [PATCH] of: introduce event tracepoints for dynamic device_node lifecyle To: Michael Ellerman , "Oliver O'Halloran" , Rob Herring References: <1492475525-10827-1-git-send-email-tyreld@linux.vnet.ibm.com> <87y3uw66y5.fsf@concordia.ellerman.id.au> Cc: "devicetree@vger.kernel.org" , linuxppc-dev , "linux-kernel@vger.kernel.org" , rostedt@goodmis.org, Ingo Molnar , Tyrel Datwyler , Nathan Fontenot , Frank Rowand From: Tyrel Datwyler Date: Wed, 19 Apr 2017 14:13:50 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <87y3uw66y5.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17041921-0056-0000-0000-000003440CC5 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006941; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00849768; UDB=6.00419634; IPR=6.00628401; BA=6.00005304; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015098; XFM=3.00000013; UTC=2017-04-19 21:13:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17041921-0057-0000-0000-0000077A1EEE Message-Id: <5aa699db-255a-773b-7d60-3c6f05e88050@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-19_16:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1704190176 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/19/2017 03:13 AM, Michael Ellerman wrote: > Oliver O'Halloran writes: > >> On Wed, Apr 19, 2017 at 2:46 AM, Rob Herring wrote: >>> On Mon, Apr 17, 2017 at 7:32 PM, Tyrel Datwyler >>> wrote: >>>> This patch introduces event tracepoints for tracking a device_nodes >>>> reference cycle as well as reconfig notifications generated in response >>>> to node/property manipulations. >>>> >>>> With the recent upstreaming of the refcount API several device_node >>>> underflows and leaks have come to my attention in the pseries (DLPAR) dynamic >>>> logical partitioning code (ie. POWER speak for hotplugging virtual and physcial >>>> resources at runtime such as cpus or IOAs). These tracepoints provide a >>>> easy and quick mechanism for validating the reference counting of >>>> device_nodes during their lifetime. >>> >>> Not really relevant for this patch, but since you are looking at >>> pseries and refcounting, the refcounting largely exists for pseries. >>> It's also hard to get right as this type of fix is fairly common. It's >>> now used for overlays, but we really probably only need to refcount >>> the overlays or changesets as a whole, not at a node level. If you >>> have any thoughts on how a different model of refcounting could work >>> for pseries, I'd like to discuss it. >> >> One idea I've been kicking around is differentiating short and long >> term references to a node. > > I actually did this a long time ago, but balked at the size of the patch > to do the conversion. Let me see if I can find it lying around ... It would be interesting to revisit this, and toss around any other ideas anyone may have. -Tyrel > > cheers > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >