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GET /api/patches/73421/?format=api
{ "id": 73421, "url": "https://patches.dpdk.org/api/patches/73421/?format=api", "web_url": "https://patches.dpdk.org/project/dpdk/patch/1594120403-17643-1-git-send-email-phil.yang@arm.com/", "project": { "id": 1, "url": "https://patches.dpdk.org/api/projects/1/?format=api", "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", "list_archive_url": "https://inbox.dpdk.org/dev", "list_archive_url_format": "https://inbox.dpdk.org/dev/{}", "commit_url_format": "" }, "msgid": "<1594120403-17643-1-git-send-email-phil.yang@arm.com>", "list_archive_url": "https://inbox.dpdk.org/dev/1594120403-17643-1-git-send-email-phil.yang@arm.com", "date": "2020-07-07T11:13:20", "name": "[v3,1/4] eventdev: fix race condition on timer list counter", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": true, "hash": "8a0beb4f3715c11366d85b5bf0c4007bd2154962", "submitter": { "id": 833, "url": "https://patches.dpdk.org/api/people/833/?format=api", "name": "Phil Yang", "email": "phil.yang@arm.com" }, "delegate": { "id": 310, "url": "https://patches.dpdk.org/api/users/310/?format=api", "username": "jerin", "first_name": "Jerin", "last_name": "Jacob", "email": "jerinj@marvell.com" }, "mbox": "https://patches.dpdk.org/project/dpdk/patch/1594120403-17643-1-git-send-email-phil.yang@arm.com/mbox/", "series": [ { "id": 10847, "url": "https://patches.dpdk.org/api/series/10847/?format=api", "web_url": "https://patches.dpdk.org/project/dpdk/list/?series=10847", "date": "2020-07-07T11:13:20", "name": "[v3,1/4] eventdev: fix race condition on timer list counter", "version": 3, "mbox": "https://patches.dpdk.org/series/10847/mbox/" } ], "comments": "https://patches.dpdk.org/api/patches/73421/comments/", "check": "success", "checks": "https://patches.dpdk.org/api/patches/73421/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<dev-bounces@dpdk.org>", "X-Original-To": "patchwork@inbox.dpdk.org", "Delivered-To": "patchwork@inbox.dpdk.org", "Received": [ "from dpdk.org (dpdk.org [92.243.14.124])\n\tby inbox.dpdk.org (Postfix) with ESMTP id 2B4E8A00BE;\n\tTue, 7 Jul 2020 13:14:38 +0200 (CEST)", "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id EB3B91DDEC;\n\tTue, 7 Jul 2020 13:14:37 +0200 (CEST)", "from foss.arm.com (foss.arm.com [217.140.110.172])\n by dpdk.org (Postfix) with ESMTP id 56FC51DDEA;\n Tue, 7 Jul 2020 13:14:36 +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 C7FFB1FB;\n Tue, 7 Jul 2020 04:14:35 -0700 (PDT)", "from phil-VirtualBox.shanghai.arm.com\n (phil-VirtualBox.shanghai.arm.com [10.169.109.153])\n by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9607B3F71E;\n Tue, 7 Jul 2020 04:14:31 -0700 (PDT)" ], "From": "Phil Yang <phil.yang@arm.com>", "To": "thomas@monjalon.net,\n\terik.g.carrillo@intel.com,\n\tdev@dpdk.org", "Cc": "jerinj@marvell.com, Honnappa.Nagarahalli@arm.com, drc@linux.vnet.ibm.com,\n Ruifeng.Wang@arm.com, Dharmik.Thakkar@arm.com, nd@arm.com,\n david.marchand@redhat.com, mdr@ashroe.eu, nhorman@tuxdriver.com,\n dodji@redhat.com, stable@dpdk.org", "Date": "Tue, 7 Jul 2020 19:13:20 +0800", "Message-Id": "<1594120403-17643-1-git-send-email-phil.yang@arm.com>", "X-Mailer": "git-send-email 2.7.4", "In-Reply-To": "<1593667604-12029-1-git-send-email-phil.yang@arm.com>", "References": "<1593667604-12029-1-git-send-email-phil.yang@arm.com>", "Subject": "[dpdk-dev] [PATCH v3 1/4] eventdev: fix race condition on timer\n\tlist counter", "X-BeenThere": "dev@dpdk.org", "X-Mailman-Version": "2.1.15", "Precedence": "list", "List-Id": "DPDK patches and discussions <dev.dpdk.org>", "List-Unsubscribe": "<https://mails.dpdk.org/options/dev>,\n <mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://mails.dpdk.org/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<https://mails.dpdk.org/listinfo/dev>,\n <mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@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": [ "v3", "1/4" ] }