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{
    "id": 73457,
    "url": "https://patches.dpdk.org/api/patches/73457/",
    "web_url": "https://patches.dpdk.org/patch/73457/",
    "project": {
        "id": 1,
        "url": "https://patches.dpdk.org/api/projects/1/",
        "name": "DPDK",
        "link_name": "dpdk",
        "list_id": "dev.dpdk.org",
        "list_email": "dev@dpdk.org",
        "web_url": "http://core.dpdk.org",
        "scm_url": "git://dpdk.org/dpdk",
        "webscm_url": "http://git.dpdk.org/dpdk"
    },
    "msgid": "<1594137293-22468-1-git-send-email-phil.yang@arm.com>",
    "date": "2020-07-07T15:54:50",
    "name": "[v4,1/4] eventdev: fix race condition on timer list counter",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": true,
    "hash": "8a0beb4f3715c11366d85b5bf0c4007bd2154962",
    "submitter": {
        "id": 833,
        "url": "https://patches.dpdk.org/api/people/833/",
        "name": "Phil Yang",
        "email": "phil.yang@arm.com"
    },
    "delegate": {
        "id": 310,
        "url": "https://patches.dpdk.org/api/users/310/",
        "username": "jerin",
        "first_name": "Jerin",
        "last_name": "Jacob",
        "email": "jerin.jacob@caviumnetworks.com"
    },
    "mbox": "https://patches.dpdk.org/patch/73457/mbox/",
    "series": [
        {
            "id": 10861,
            "url": "https://patches.dpdk.org/api/series/10861/",
            "web_url": "https://patches.dpdk.org/project/dpdk/list/?series=10861",
            "date": "2020-07-07T15:54:50",
            "name": "[v4,1/4] eventdev: fix race condition on timer list counter",
            "version": 4,
            "mbox": "https://patches.dpdk.org/series/10861/mbox/"
        }
    ],
    "comments": "https://patches.dpdk.org/api/patches/73457/comments/",
    "check": "fail",
    "checks": "https://patches.dpdk.org/api/patches/73457/checks/",
    "tags": {},
    "headers": {
        "Return-Path": "<dev-bounces@dpdk.org>",
        "References": "<1594120403-17643-1-git-send-email-phil.yang@arm.com>",
        "X-Mailman-Version": "2.1.15",
        "Date": "Tue,  7 Jul 2020 23:54:50 +0800",
        "X-BeenThere": "dev@dpdk.org",
        "Message-Id": "<1594137293-22468-1-git-send-email-phil.yang@arm.com>",
        "X-Original-To": "patchwork@inbox.dpdk.org",
        "Received": [
            "from dpdk.org (dpdk.org [92.243.14.124])\n\tby inbox.dpdk.org (Postfix) with ESMTP id DD97EA00BE;\n\tTue,  7 Jul 2020 17:55:21 +0200 (CEST)",
            "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 9D7001DE9A;\n\tTue,  7 Jul 2020 17:55:20 +0200 (CEST)",
            "from foss.arm.com (foss.arm.com [217.140.110.172])\n by dpdk.org (Postfix) with ESMTP id 486771D664;\n Tue,  7 Jul 2020 17:55:19 +0200 (CEST)",
            "from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14])\n by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9A2441FB;\n Tue,  7 Jul 2020 08:55:18 -0700 (PDT)",
            "from phil-VirtualBox.arm.com (A010647.Arm.com [10.170.226.105])\n by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 470543F68F;\n Tue,  7 Jul 2020 08:55:14 -0700 (PDT)"
        ],
        "List-Post": "<mailto:dev@dpdk.org>",
        "List-Help": "<mailto:dev-request@dpdk.org?subject=help>",
        "Sender": "\"dev\" <dev-bounces@dpdk.org>",
        "X-Mailer": "git-send-email 2.7.4",
        "Precedence": "list",
        "From": "Phil Yang <phil.yang@arm.com>",
        "Subject": "[dpdk-dev] [PATCH v4 1/4] eventdev: fix race condition on timer\n\tlist counter",
        "List-Archive": "<http://mails.dpdk.org/archives/dev/>",
        "Errors-To": "dev-bounces@dpdk.org",
        "List-Subscribe": "<https://mails.dpdk.org/listinfo/dev>,\n <mailto:dev-request@dpdk.org?subject=subscribe>",
        "Cc": "thomas@monjalon.net, erik.g.carrillo@intel.com,\n Honnappa.Nagarahalli@arm.com, drc@linux.vnet.ibm.com, Ruifeng.Wang@arm.com,\n Dharmik.Thakkar@arm.com, nd@arm.com, david.marchand@redhat.com,\n mdr@ashroe.eu, nhorman@tuxdriver.com, dodji@redhat.com, stable@dpdk.org",
        "List-Id": "DPDK patches and discussions <dev.dpdk.org>",
        "Delivered-To": "patchwork@inbox.dpdk.org",
        "In-Reply-To": "<1594120403-17643-1-git-send-email-phil.yang@arm.com>",
        "List-Unsubscribe": "<https://mails.dpdk.org/options/dev>,\n <mailto:dev-request@dpdk.org?subject=unsubscribe>",
        "To": "jerinj@marvell.com,\n\tdev@dpdk.org"
    },
    "content": "The n_poll_lcores counter and poll_lcore array are shared between lcores\nand the update of these variables are out of the protection of spinlock\non each lcore timer list. The read-modify-write operations of the counter\nare not atomic, so it has the potential of race condition between lcores.\n\nUse c11 atomics with RELAXED ordering to prevent confliction.\n\nFixes: cc7b73ea9e3b (\"eventdev: add new software timer adapter\")\nCc: erik.g.carrillo@intel.com\nCc: stable@dpdk.org\n\nSigned-off-by: Phil Yang <phil.yang@arm.com>\nReviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>\nReviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>\nAcked-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>\n---\nv2:\nAlign the code. (Erik)\n\n lib/librte_eventdev/rte_event_timer_adapter.c | 16 ++++++++++++----\n 1 file changed, 12 insertions(+), 4 deletions(-)",
    "diff": "diff --git a/lib/librte_eventdev/rte_event_timer_adapter.c b/lib/librte_eventdev/rte_event_timer_adapter.c\nindex 2321803..370ea40 100644\n--- a/lib/librte_eventdev/rte_event_timer_adapter.c\n+++ b/lib/librte_eventdev/rte_event_timer_adapter.c\n@@ -583,6 +583,7 @@ swtim_callback(struct rte_timer *tim)\n \tuint16_t nb_evs_invalid = 0;\n \tuint64_t opaque;\n \tint ret;\n+\tint n_lcores;\n \n \topaque = evtim->impl_opaque[1];\n \tadapter = (struct rte_event_timer_adapter *)(uintptr_t)opaque;\n@@ -605,8 +606,12 @@ swtim_callback(struct rte_timer *tim)\n \t\t\t\t      \"with immediate expiry value\");\n \t\t}\n \n-\t\tif (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore].v)))\n-\t\t\tsw->poll_lcores[sw->n_poll_lcores++] = lcore;\n+\t\tif (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore].v))) {\n+\t\t\tn_lcores = __atomic_fetch_add(&sw->n_poll_lcores, 1,\n+\t\t\t\t\t\t     __ATOMIC_RELAXED);\n+\t\t\t__atomic_store_n(&sw->poll_lcores[n_lcores], lcore,\n+\t\t\t\t\t__ATOMIC_RELAXED);\n+\t\t}\n \t} else {\n \t\tEVTIM_BUF_LOG_DBG(\"buffered an event timer expiry event\");\n \n@@ -1011,6 +1016,7 @@ __swtim_arm_burst(const struct rte_event_timer_adapter *adapter,\n \tuint32_t lcore_id = rte_lcore_id();\n \tstruct rte_timer *tim, *tims[nb_evtims];\n \tuint64_t cycles;\n+\tint n_lcores;\n \n #ifdef RTE_LIBRTE_EVENTDEV_DEBUG\n \t/* Check that the service is running. */\n@@ -1033,8 +1039,10 @@ __swtim_arm_burst(const struct rte_event_timer_adapter *adapter,\n \tif (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore_id].v))) {\n \t\tEVTIM_LOG_DBG(\"Adding lcore id = %u to list of lcores to poll\",\n \t\t\t      lcore_id);\n-\t\tsw->poll_lcores[sw->n_poll_lcores] = lcore_id;\n-\t\t++sw->n_poll_lcores;\n+\t\tn_lcores = __atomic_fetch_add(&sw->n_poll_lcores, 1,\n+\t\t\t\t\t     __ATOMIC_RELAXED);\n+\t\t__atomic_store_n(&sw->poll_lcores[n_lcores], lcore_id,\n+\t\t\t\t__ATOMIC_RELAXED);\n \t}\n \n \tret = rte_mempool_get_bulk(sw->tim_pool, (void **)tims,\n",
    "prefixes": [
        "v4",
        "1/4"
    ]
}