From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3w7ZVt5LXjzDq9P for ; Thu, 20 Apr 2017 07:13:58 +1000 (AEST) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3JL8b5Z123290 for ; Wed, 19 Apr 2017 17:13:56 -0400 Received: from e19.ny.us.ibm.com (e19.ny.us.ibm.com [129.33.205.209]) by mx0a-001b2d01.pphosted.com with ESMTP id 29x74n8nd1-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 19 Apr 2017 17:13:56 -0400 Received: from localhost by e19.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 19 Apr 2017 17:13:55 -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 MIME-Version: 1.0 In-Reply-To: <87y3uw66y5.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=windows-1252 Message-Id: <5aa699db-255a-773b-7d60-3c6f05e88050@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 >