From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id C51BEA034E for ; Thu, 23 Apr 2020 18:32:06 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 9C2CF1C2F5; Thu, 23 Apr 2020 18:32:06 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 84D8B1C2F5; Thu, 23 Apr 2020 18:32:05 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0B88730E; Thu, 23 Apr 2020 09:32:05 -0700 (PDT) Received: from phil-VirtualBox.arm.com (A010647.Arm.com [10.170.243.60]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C77A93F68F; Thu, 23 Apr 2020 09:32:01 -0700 (PDT) From: Phil Yang To: harry.van.haaren@intel.com, dev@dpdk.org Cc: thomas@monjalon.net, david.marchand@redhat.com, konstantin.ananyev@intel.com, jerinj@marvell.com, hemant.agrawal@nxp.com, Honnappa.Nagarahalli@arm.com, gavin.hu@arm.com, nd@arm.com, Honnappa Nagarahalli , stable@dpdk.org Date: Fri, 24 Apr 2020 00:31:18 +0800 Message-Id: <1587659482-27133-3-git-send-email-phil.yang@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1587659482-27133-1-git-send-email-phil.yang@arm.com> References: <1584407863-774-8-git-send-email-phil.yang@arm.com> <1587659482-27133-1-git-send-email-phil.yang@arm.com> Subject: [dpdk-stable] [PATCH v2 2/6] service: identify service running on another core correctly X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: stable-bounces@dpdk.org Sender: "stable" From: Honnappa Nagarahalli The logic to identify if the MT unsafe service is running on another core can return -EBUSY spuriously. In such cases, running the service becomes costlier than using atomic operations. Assume that the application passes the right parameters and reduces the number of instructions for all cases. Cc: stable@dpdk.org Fixes: 8d39d3e237c2 ("service: fix race in service on app lcore function") Signed-off-by: Honnappa Nagarahalli Reviewed-by: Phil Yang --- lib/librte_eal/common/rte_service.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c index b8c465e..c89472b 100644 --- a/lib/librte_eal/common/rte_service.c +++ b/lib/librte_eal/common/rte_service.c @@ -360,7 +360,7 @@ rte_service_runner_do_callback(struct rte_service_spec_impl *s, /* Expects the service 's' is valid. */ static int32_t service_run(uint32_t i, struct core_state *cs, uint64_t service_mask, - struct rte_service_spec_impl *s) + struct rte_service_spec_impl *s, uint32_t serialize_mt_unsafe) { if (!s) return -EINVAL; @@ -374,7 +374,7 @@ service_run(uint32_t i, struct core_state *cs, uint64_t service_mask, cs->service_active_on_lcore[i] = 1; - if (service_mt_safe(s) == 0) { + if ((service_mt_safe(s) == 0) && (serialize_mt_unsafe == 1)) { if (!rte_atomic32_cmpset((uint32_t *)&s->execute_lock, 0, 1)) return -EBUSY; @@ -412,24 +412,14 @@ rte_service_run_iter_on_app_lcore(uint32_t id, uint32_t serialize_mt_unsafe) SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL); - /* Atomically add this core to the mapped cores first, then examine if - * we can run the service. This avoids a race condition between - * checking the value, and atomically adding to the mapped count. + /* Increment num_mapped_cores to indicate that the service + * is running on a core. */ - if (serialize_mt_unsafe) - rte_atomic32_inc(&s->num_mapped_cores); + rte_atomic32_inc(&s->num_mapped_cores); - if (service_mt_safe(s) == 0 && - rte_atomic32_read(&s->num_mapped_cores) > 1) { - if (serialize_mt_unsafe) - rte_atomic32_dec(&s->num_mapped_cores); - return -EBUSY; - } - - int ret = service_run(id, cs, UINT64_MAX, s); + int ret = service_run(id, cs, UINT64_MAX, s, serialize_mt_unsafe); - if (serialize_mt_unsafe) - rte_atomic32_dec(&s->num_mapped_cores); + rte_atomic32_dec(&s->num_mapped_cores); return ret; } @@ -449,7 +439,7 @@ rte_service_runner_func(void *arg) if (!service_valid(i)) continue; /* return value ignored as no change to code flow */ - service_run(i, cs, service_mask, service_get(i)); + service_run(i, cs, service_mask, service_get(i), 1); } cs->loops++; -- 2.7.4