From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 0D85441DEE; Mon, 6 Mar 2023 02:41:16 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 9D09340ED6; Mon, 6 Mar 2023 02:41:15 +0100 (CET) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by mails.dpdk.org (Postfix) with ESMTP id 19B2840E03 for ; Mon, 6 Mar 2023 02:41:13 +0100 (CET) Received: from dggpeml500024.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4PVLqv2qgjzrS4k; Mon, 6 Mar 2023 09:40:27 +0800 (CST) Received: from [10.67.100.224] (10.67.100.224) by dggpeml500024.china.huawei.com (7.185.36.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Mon, 6 Mar 2023 09:41:11 +0800 Subject: Re: [PATCH 1/5] ethdev: fix race-condition of proactive error handling mode To: Ferruh Yigit , Konstantin Ananyev , "thomas@monjalon.net" , Andrew Rybchenko , Kalesh AP , Ajit Khaparde CC: "dev@dpdk.org" References: <20230301030610.49468-1-fengchengwen@huawei.com> <20230301030610.49468-2-fengchengwen@huawei.com> <0f387ca1eee34a7f92745de7b59a71a1@huawei.com> From: fengchengwen Message-ID: Date: Mon, 6 Mar 2023 09:41:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.100.224] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500024.china.huawei.com (7.185.36.10) X-CFilter-Loop: Reflected X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 2023/3/4 0:51, Ferruh Yigit wrote: > On 3/2/2023 12:08 PM, Konstantin Ananyev wrote: >> >>> In the proactive error handling mode, the PMD will set the data path >>> pointers to dummy functions and then try recovery, in this period the >>> application may still invoking data path API. This will introduce a >>> race-condition with data path which may lead to crash [1]. >>> >>> Although the PMD added delay after setting data path pointers to cover >>> the above race-condition, it reduces the probability, but it doesn't >>> solve the problem. >>> >>> To solve the race-condition problem fundamentally, the following >>> requirements are added: >>> 1. The PMD should set the data path pointers to dummy functions after >>> report RTE_ETH_EVENT_ERR_RECOVERING event. >>> 2. The application should stop data path API invocation when process >>> the RTE_ETH_EVENT_ERR_RECOVERING event. >>> 3. The PMD should set the data path pointers to valid functions before >>> report RTE_ETH_EVENT_RECOVERY_SUCCESS event. >>> 4. The application should enable data path API invocation when process >>> the RTE_ETH_EVENT_RECOVERY_SUCCESS event. >>> > > How this is solving the race-condition, by pushing responsibility to > stop data path to application? Yes, I think it's more practical to collaborate with application. The application will control API invocation (including control and data path), >From a DPDK SDK perspective, it has a God perspective. > > What if application is not interested in recovery modes at all and not > registered any callback for the recovery? There's probably race-condition which may lead to crash, because DPDK worker threads runs busyloop and located on isolated core, and also PMDs add delay time, the actual probability of occurence is very very low, at least for HNS3 pmd it has not run out for at least four years. > > I think driver should not rely on application for this, unless > application explicitly says (to driver) that it is handling recovery, If application register the event callback, the PMD could deduce that application will know this. If application not register, then PMD will recovery itself and maybe race-condition. > right now there is no way for driver to know this. > > >>> Also, this patch introduce a driver internal function >>> rte_eth_fp_ops_setup which used as an help function for PMD. >>> >>> [1] http://patchwork.dpdk.org/project/dpdk/patch/20230220060839.1267349-2-ashok.k.kaladi@intel.com/ >>> >>> Fixes: eb0d471a8941 ("ethdev: add proactive error handling mode") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Chengwen Feng >>> --- >>> doc/guides/prog_guide/poll_mode_drv.rst | 20 +++++++--------- >>> lib/ethdev/ethdev_driver.c | 8 +++++++ >>> lib/ethdev/ethdev_driver.h | 10 ++++++++ >>> lib/ethdev/rte_ethdev.h | 32 +++++++++++++++---------- >>> lib/ethdev/version.map | 1 + >>> 5 files changed, 46 insertions(+), 25 deletions(-) >>> >>> diff --git a/doc/guides/prog_guide/poll_mode_drv.rst b/doc/guides/prog_guide/poll_mode_drv.rst >>> index c145a9066c..e380ff135a 100644 >>> --- a/doc/guides/prog_guide/poll_mode_drv.rst >>> +++ b/doc/guides/prog_guide/poll_mode_drv.rst >>> @@ -638,14 +638,9 @@ different from the application invokes recovery in PASSIVE mode, >>> the PMD automatically recovers from error in PROACTIVE mode, >>> and only a small amount of work is required for the application. >>> >>> -During error detection and automatic recovery, >>> -the PMD sets the data path pointers to dummy functions >>> -(which will prevent the crash), >>> -and also make sure the control path operations fail with a return code ``-EBUSY``. >>> - >>> -Because the PMD recovers automatically, >>> -the application can only sense that the data flow is disconnected for a while >>> -and the control API returns an error in this period. >>> +During error detection and automatic recovery, the PMD sets the data path >>> +pointers to dummy functions and also make sure the control path operations >>> +failed with a return code ``-EBUSY``. >>> >>> In order to sense the error happening/recovering, >>> as well as to restore some additional configuration, >>> @@ -653,9 +648,9 @@ three events are available: >>> >>> ``RTE_ETH_EVENT_ERR_RECOVERING`` >>> Notify the application that an error is detected >>> - and the recovery is being started. >>> + and the recovery is about to start. >>> Upon receiving the event, the application should not invoke >>> - any control path function until receiving >>> + any control and data path API until receiving >>> ``RTE_ETH_EVENT_RECOVERY_SUCCESS`` or ``RTE_ETH_EVENT_RECOVERY_FAILED`` event. >>> >>> .. note:: >>> @@ -666,8 +661,9 @@ three events are available: >>> >>> ``RTE_ETH_EVENT_RECOVERY_SUCCESS`` >>> Notify the application that the recovery from error is successful, >>> - the PMD already re-configures the port, >>> - and the effect is the same as a restart operation. >>> + the PMD already re-configures the port. >>> + The application should restore some additional configuration, and then >>> + enable data path API invocation. >>> >>> ``RTE_ETH_EVENT_RECOVERY_FAILED`` >>> Notify the application that the recovery from error failed, >>> diff --git a/lib/ethdev/ethdev_driver.c b/lib/ethdev/ethdev_driver.c >>> index 0be1e8ca04..f994653fe9 100644 >>> --- a/lib/ethdev/ethdev_driver.c >>> +++ b/lib/ethdev/ethdev_driver.c >>> @@ -515,6 +515,14 @@ rte_eth_dma_zone_free(const struct rte_eth_dev *dev, const char *ring_name, >>> return rc; >>> } >>> >>> +void >>> +rte_eth_fp_ops_setup(struct rte_eth_dev *dev) >>> +{ >>> + if (dev == NULL) >>> + return; >>> + eth_dev_fp_ops_setup(rte_eth_fp_ops + dev->data->port_id, dev); >>> +} >>> + >>> const struct rte_memzone * >>> rte_eth_dma_zone_reserve(const struct rte_eth_dev *dev, const char *ring_name, >>> uint16_t queue_id, size_t size, unsigned int align, >>> diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h >>> index 2c9d615fb5..0d964d1f67 100644 >>> --- a/lib/ethdev/ethdev_driver.h >>> +++ b/lib/ethdev/ethdev_driver.h >>> @@ -1621,6 +1621,16 @@ int >>> rte_eth_dma_zone_free(const struct rte_eth_dev *eth_dev, const char *name, >>> uint16_t queue_id); >>> >>> +/** >>> + * @internal >>> + * Setup eth fast-path API to ethdev values. >>> + * >>> + * @param dev >>> + * Pointer to struct rte_eth_dev. >>> + */ >>> +__rte_internal >>> +void rte_eth_fp_ops_setup(struct rte_eth_dev *dev); >>> + >>> /** >>> * @internal >>> * Atomically set the link status for the specific device. >>> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h >>> index 049641d57c..44ee7229c1 100644 >>> --- a/lib/ethdev/rte_ethdev.h >>> +++ b/lib/ethdev/rte_ethdev.h >>> @@ -3944,25 +3944,28 @@ enum rte_eth_event_type { >>> */ >>> RTE_ETH_EVENT_RX_AVAIL_THRESH, >>> /** Port recovering from a hardware or firmware error. >>> - * If PMD supports proactive error recovery, >>> - * it should trigger this event to notify application >>> - * that it detected an error and the recovery is being started. >>> - * Upon receiving the event, the application should not invoke any control path API >>> - * (such as rte_eth_dev_configure/rte_eth_dev_stop...) until receiving >>> - * RTE_ETH_EVENT_RECOVERY_SUCCESS or RTE_ETH_EVENT_RECOVERY_FAILED event. >>> - * The PMD will set the data path pointers to dummy functions, >>> - * and re-set the data path pointers to non-dummy functions >>> - * before reporting RTE_ETH_EVENT_RECOVERY_SUCCESS event. >>> - * It means that the application cannot send or receive any packets >>> - * during this period. >>> + * >>> + * If PMD supports proactive error recovery, it should trigger this >>> + * event to notify application that it detected an error and the >>> + * recovery is about to start. >>> + * >>> + * Upon receiving the event, the application should not invoke any >>> + * control and data path API until receiving >>> + * RTE_ETH_EVENT_RECOVERY_SUCCESS or RTE_ETH_EVENT_RECOVERY_FAILED >>> + * event. >>> + * >>> + * Once this event is reported, the PMD will set the data path pointers >>> + * to dummy functions, and re-set the data path pointers to valid >>> + * functions before reporting RTE_ETH_EVENT_RECOVERY_SUCCESS event. >>> + * >>> * @note Before the PMD reports the recovery result, >>> * the PMD may report the RTE_ETH_EVENT_ERR_RECOVERING event again, >>> * because a larger error may occur during the recovery. >>> */ >>> RTE_ETH_EVENT_ERR_RECOVERING, >>> /** Port recovers successfully from the error. >>> - * The PMD already re-configured the port, >>> - * and the effect is the same as a restart operation. >>> + * >>> + * The PMD already re-configured the port: >>> * a) The following operation will be retained: (alphabetically) >>> * - DCB configuration >>> * - FEC configuration >>> @@ -3989,6 +3992,9 @@ enum rte_eth_event_type { >>> * (@see RTE_ETH_DEV_CAPA_FLOW_SHARED_OBJECT_KEEP) >>> * c) Any other configuration will not be stored >>> * and will need to be re-configured. >>> + * >>> + * The application should restore some additional configuration >>> + * (see above case b/c), and then enable data path API invocation. >>> */ >>> RTE_ETH_EVENT_RECOVERY_SUCCESS, >>> /** Port recovery failed. >>> diff --git a/lib/ethdev/version.map b/lib/ethdev/version.map >>> index 357d1a88c0..c273e0bdae 100644 >>> --- a/lib/ethdev/version.map >>> +++ b/lib/ethdev/version.map >>> @@ -320,6 +320,7 @@ INTERNAL { >>> rte_eth_devices; >>> rte_eth_dma_zone_free; >>> rte_eth_dma_zone_reserve; >>> + rte_eth_fp_ops_setup; >>> rte_eth_hairpin_queue_peer_bind; >>> rte_eth_hairpin_queue_peer_unbind; >>> rte_eth_hairpin_queue_peer_update; >>> -- >> >> Acked-by: Konstantin Ananyev >> >>> 2.17.1 >> > > . >