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GET /api/1.2/patches/833371/?format=api
{ "id": 833371, "url": "http://patchwork.ozlabs.org/api/1.2/patches/833371/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/patch/20171102140501.87671-11-gwalbon@linux.vnet.ibm.com/", "project": { "id": 15, "url": "http://patchwork.ozlabs.org/api/1.2/projects/15/?format=api", "name": "Ubuntu Kernel", "link_name": "ubuntu-kernel", "list_id": "kernel-team.lists.ubuntu.com", "list_email": "kernel-team@lists.ubuntu.com", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20171102140501.87671-11-gwalbon@linux.vnet.ibm.com>", "list_archive_url": null, "date": "2017-11-02T14:04:59", "name": "[Artful,10/12] powerpc/perf: Fix for core/nest imc call trace on cpuhotplug", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "facbb62e8800a6403282d861660558570f0a56ac", "submitter": { "id": 71662, "url": "http://patchwork.ozlabs.org/api/1.2/people/71662/?format=api", "name": "Gustavo Walbon", "email": "gwalbon@linux.vnet.ibm.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/ubuntu-kernel/patch/20171102140501.87671-11-gwalbon@linux.vnet.ibm.com/mbox/", "series": [ { "id": 11509, "url": "http://patchwork.ozlabs.org/api/1.2/series/11509/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/list/?series=11509", "date": "2017-11-02T14:04:50", "name": "Backport for Power9 Nest PMU Instrumentation", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/11509/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/833371/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/833371/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<kernel-team-bounces@lists.ubuntu.com>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org", "Authentication-Results": "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=lists.ubuntu.com\n\t(client-ip=91.189.94.19; helo=huckleberry.canonical.com;\n\tenvelope-from=kernel-team-bounces@lists.ubuntu.com;\n\treceiver=<UNKNOWN>)", "Received": [ "from huckleberry.canonical.com (huckleberry.canonical.com\n\t[91.189.94.19])\n\tby ozlabs.org (Postfix) with ESMTP id 3ySRgg0P3gz9sNw;\n\tFri, 3 Nov 2017 01:05:35 +1100 (AEDT)", "from localhost ([127.0.0.1] helo=huckleberry.canonical.com)\n\tby huckleberry.canonical.com with esmtp (Exim 4.86_2)\n\t(envelope-from <kernel-team-bounces@lists.ubuntu.com>)\n\tid 1eAG7f-0002RL-1H; Thu, 02 Nov 2017 14:05:31 +0000", "from mx0a-001b2d01.pphosted.com ([148.163.156.1])\n\tby huckleberry.canonical.com with esmtps\n\t(TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2)\n\t(envelope-from <gwalbon@linux.vnet.ibm.com>) id 1eAG7d-0002MK-2u\n\tfor kernel-team@lists.ubuntu.com; Thu, 02 Nov 2017 14:05:29 +0000", "from pps.filterd (m0098393.ppops.net [127.0.0.1])\n\tby mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id\n\tvA2E4RnS081658\n\tfor <kernel-team@lists.ubuntu.com>; Thu, 2 Nov 2017 10:05:27 -0400", "from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202])\n\tby mx0a-001b2d01.pphosted.com with ESMTP id 2e03jm5862-1\n\t(version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT)\n\tfor <kernel-team@lists.ubuntu.com>; Thu, 02 Nov 2017 10:05:27 -0400", "from localhost\n\tby e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use\n\tOnly! Violators will be prosecuted\n\tfor <kernel-team@lists.ubuntu.com> from <gwalbon@linux.vnet.ibm.com>; \n\tThu, 2 Nov 2017 10:05:26 -0400", "from b01cxnp23033.gho.pok.ibm.com (9.57.198.28)\n\tby e12.ny.us.ibm.com (146.89.104.199) with IBM ESMTP SMTP Gateway:\n\tAuthorized Use Only! Violators will be prosecuted; \n\tThu, 2 Nov 2017 10:05:23 -0400", "from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com\n\t[9.57.199.110])\n\tby b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP\n\tid vA2E5Liv60293372; Thu, 2 Nov 2017 14:05:23 GMT", "from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1])\n\tby IMSVA (Postfix) with ESMTP id 98354AE052;\n\tThu, 2 Nov 2017 10:06:09 -0400 (EDT)", "from localhost (unknown [9.85.138.60])\n\tby b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP id 09951AE03C;\n\tThu, 2 Nov 2017 10:06:08 -0400 (EDT)" ], "From": "Gustavo Walbon <gwalbon@linux.vnet.ibm.com>", "To": "kernel-team@lists.ubuntu.com", "Subject": "[Artful][PATCH 10/12] powerpc/perf: Fix for core/nest imc call trace\n\ton cpuhotplug", "Date": "Thu, 2 Nov 2017 12:04:59 -0200", "X-Mailer": "git-send-email 2.13.3", "In-Reply-To": "<20171102140501.87671-1-gwalbon@linux.vnet.ibm.com>", "References": "<20171102140501.87671-1-gwalbon@linux.vnet.ibm.com>", "X-TM-AS-GCONF": "00", "x-cbid": "17110214-0048-0000-0000-000001FF6938", "X-IBM-SpamModules-Scores": "", "X-IBM-SpamModules-Versions": "BY=3.00007997; HX=3.00000241; KW=3.00000007;\n\tPH=3.00000004; SC=3.00000239; SDB=6.00940090; UDB=6.00474019;\n\tIPR=6.00720346; \n\tBA=6.00005666; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009;\n\tZB=6.00000000; \n\tZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017836;\n\tXFM=3.00000015; UTC=2017-11-02 14:05:24", "X-IBM-AV-DETECTION": "SAVI=unused REMOTE=unused XFE=unused", "x-cbparentid": "17110214-0049-0000-0000-0000430E79FF", "Message-Id": "<20171102140501.87671-11-gwalbon@linux.vnet.ibm.com>", "X-Proofpoint-Virus-Version": "vendor=fsecure engine=2.50.10432:, ,\n\tdefinitions=2017-11-02_05:, , signatures=0", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n\tpriorityscore=1501\n\tmalwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0\n\tclxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0\n\tclassifier=spam adjust=0 reason=mlx scancount=1\n\tengine=8.0.1-1707230000\n\tdefinitions=main-1711020178", "X-BeenThere": "kernel-team@lists.ubuntu.com", "X-Mailman-Version": "2.1.20", "Precedence": "list", "List-Id": "Kernel team discussions <kernel-team.lists.ubuntu.com>", "List-Unsubscribe": "<https://lists.ubuntu.com/mailman/options/kernel-team>,\n\t<mailto:kernel-team-request@lists.ubuntu.com?subject=unsubscribe>", "List-Archive": "<https://lists.ubuntu.com/archives/kernel-team>", "List-Post": "<mailto:kernel-team@lists.ubuntu.com>", "List-Help": "<mailto:kernel-team-request@lists.ubuntu.com?subject=help>", "List-Subscribe": "<https://lists.ubuntu.com/mailman/listinfo/kernel-team>,\n\t<mailto:kernel-team-request@lists.ubuntu.com?subject=subscribe>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "base64", "Errors-To": "kernel-team-bounces@lists.ubuntu.com", "Sender": "\"kernel-team\" <kernel-team-bounces@lists.ubuntu.com>" }, "content": "From: Anju T Sudhakar <anju@linux.vnet.ibm.com>\n\nBugLink: https://bugs.launchpad.net/bugs/1481347\n\nNest/core pmu units are enabled only when it is used. A reference count is\nmaintained for the events which uses the nest/core pmu units. Currently in\n*_imc_counters_release function a WARN() is used for notification of any\nunderflow of ref count.\n\nThe case where event ref count hit a negative value is, when perf session is\nstarted, followed by offlining of all cpus in a given core.\ni.e. in cpuhotplug offline path ppc_core_imc_cpu_offline() function set the\nref->count to zero, if the current cpu which is about to offline is the last\ncpu in a given core and make an OPAL call to disable the engine in that core.\nAnd on perf session termination, perf->destroy (core_imc_counters_release) will\nfirst decrement the ref->count for this core and based on the ref->count value\nan opal call is made to disable the core-imc engine.\nNow, since cpuhotplug path already clears the ref->count for core and disabled\nthe engine, perf->destroy() decrementing again at event termination make it\nnegative which in turn fires the WARN_ON. The same happens for nest units.\n\nAdd a check to see if the reference count is alreday zero, before decrementing\nthe count, so that the ref count will not hit a negative value.\n\nSigned-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>\nReviewed-by: Santosh Sivaraj <santosh@fossix.org>\nSigned-off-by: Michael Ellerman <mpe@ellerman.id.au>\n(cherry-picked from 0d923820c6db1644c27c2d0a5af8920fc0f8cd81)\nSigned-off-by: Gustavo Walbon <gwalbon@linux.vnet.ibm.com>\n---\n arch/powerpc/perf/imc-pmu.c | 28 ++++++++++++++++++++++++++++\n 1 file changed, 28 insertions(+)", "diff": "diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c\nindex 9ccac86f3463..e3a1f65933b5 100644\n--- a/arch/powerpc/perf/imc-pmu.c\n+++ b/arch/powerpc/perf/imc-pmu.c\n@@ -399,6 +399,20 @@ static void nest_imc_counters_release(struct perf_event *event)\n \n \t/* Take the mutex lock for this node and then decrement the reference count */\n \tmutex_lock(&ref->lock);\n+\tif (ref->refc == 0) {\n+\t\t/*\n+\t\t * The scenario where this is true is, when perf session is\n+\t\t * started, followed by offlining of all cpus in a given node.\n+\t\t *\n+\t\t * In the cpuhotplug offline path, ppc_nest_imc_cpu_offline()\n+\t\t * function set the ref->count to zero, if the cpu which is\n+\t\t * about to offline is the last cpu in a given node and make\n+\t\t * an OPAL call to disable the engine in that node.\n+\t\t *\n+\t\t */\n+\t\tmutex_unlock(&ref->lock);\n+\t\treturn;\n+\t}\n \tref->refc--;\n \tif (ref->refc == 0) {\n \t\trc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,\n@@ -646,6 +660,20 @@ static void core_imc_counters_release(struct perf_event *event)\n \t\treturn;\n \n \tmutex_lock(&ref->lock);\n+\tif (ref->refc == 0) {\n+\t\t/*\n+\t\t * The scenario where this is true is, when perf session is\n+\t\t * started, followed by offlining of all cpus in a given core.\n+\t\t *\n+\t\t * In the cpuhotplug offline path, ppc_core_imc_cpu_offline()\n+\t\t * function set the ref->count to zero, if the cpu which is\n+\t\t * about to offline is the last cpu in a given core and make\n+\t\t * an OPAL call to disable the engine in that core.\n+\t\t *\n+\t\t */\n+\t\tmutex_unlock(&ref->lock);\n+\t\treturn;\n+\t}\n \tref->refc--;\n \tif (ref->refc == 0) {\n \t\trc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,\n", "prefixes": [ "Artful", "10/12" ] }