On 3/6/2023 10:22 AM, 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? >>> >>> Exactly, it becomes application responsibility to make sure data-path is >>> stopped/suspended before recovery will continue. >>> >> >> From documentation of the feature: >> >> `` >> 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. >> >> In order to sense the error happening/recovering, as well as to restore >> some additional configuration, three events are available: >> `` >> >> It looks like initial design is to use events mainly inform application >> about what happened and mainly for re-configuration. >> >> Although I am don't disagree to involve the application, I am not sure >> that is part of current design. > > I thought we all agreed that initial design contain some fallacies that > need to fixed, no? > Statement that with current rte_ethdev design error recovery can be done > without interaction with the app (to stop/suspend data/control path) > is the main one I think. > It needs some interaction with app layer, one way or another. > >>>> >>>> What if application is not interested in recovery modes at all and not >>>> registered any callback for the recovery? >>> >>> >>> Are you saying there is no way for application to disable >>> automatic recovery in PMD if it is not interested >>> (or can't full-fill per-requesties for it)? >>> If so, then yes it is a problem and we need to fix it. >>> I assumed that such mechanism to disable unwanted events already exists, >>> but I can't find anything. >>> Wonder what would be the easiest way here - can PMD make a decision >>> based on callback return value, or do we need a new API to >>> enable/disable callbacks, or ...? >>> >>> >> >> As far as I can see automatic recovery is not configurable by app. >> >> But that is not all, PMD sends events to application but PMD can't know >> if application is handling them or not, so with current design PMD can't >> rely on to app. > > Well, PMD invokes user provided callback. > One way to fix that problem - if there is no callback provided, > or callback returns an error code - PMD can assume that recovery > should not be done. > That is probably not the best design choice, but at least it will allow > to fix the problem without too many changes and introducing new API. > That could be sort of a 'quick fix'. > In a meanwhile we can think about new/better approach for that. >
-rc2 for 23.03 is a few days away. What do you think to have 'quick fix' as modifying how driver updates burst ops to prevent the race condition, for this release? And plan a design update for the next release? >> >>>> I think driver should not rely on application for this, unless >>>> application explicitly says (to driver) that it is handling recovery, >>>> right now there is no way for driver to know this. >>> >>> I think it is visa-versa: >>> application should not enable auto-recovery if it can't meet >>> per-requeststies for it (provide appropriate callback). >>> >> >> I agree on above, we are saying similar thing in different perspective. > > Ok, that's good we are on the same page. > > >> >>> >>>> >>>>>> 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.kal...@intel.com/ >>>>>> >>>>>> Fixes: eb0d471a8941 ("ethdev: add proactive error handling mode") >>>>>> Cc: sta...@dpdk.org >>>>>> >>>>>> Signed-off-by: Chengwen Feng <fengcheng...@huawei.com> >>>>>> --- >>>>>> 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 <konstantin.anan...@huawei.com> >>>>> >>>>>> 2.17.1 >>>>> >>>> >>> >
