> >>>>>>>>>>> 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? > >> > >> The 'quick fix', do you mean only update function pointer (without rxq > >> setting) ? > >> Currently the PMDs which announced support "proactive error handling mode" > >> already > >> do this. > >> > > > > Yes. > > I checked hns3, it does as you said, hns3_eth_dev_fp_ops_config()' > > updates all fields in 'rte_eth_fp_ops' but only function pointer seems > > changed in the driver, resulting only function pointers to be updated. > > > > The discussion about race condition started with patch [1], which > > mentions a crash because of a race condition. Later in discussions, > > recovery event given as a sample for where the race can occur, that is > > why we are here. > > > > But after above info, although there is race condition and a bigger > > update (that needs application involvement) is required for recovery > > mechanism, there is no crash and NO 'quick fix' is required for recovery. > > > > @Konstantin, @Chengwen, can you please confirm above understanding is > > correct? > > Yes, that's what.
Yes, I think with Chengwen patch the race condition problem should be fixed. Though for that user has to provide a properly implemented callback. What is not currently addressed - user can not disable this auto-recovery procedure on his will. So if user will not provide a proper call-back the recovery can still proceed and race can happen. > > > > > > > > > [1] > > https://patches.dpdk.org/project/dpdk/patch/20230220060839.1267349-2-ashok.k.kal...@intel.com/ > > > >>>>> > >>>>> And plan a design update for the next release? > >>>> +1 on the overall approach. > >>> > >>> Yep, agree. > >> > >> Hope for better solution. > >> And also, I notice only the openvswitch (from all open-source software > >> which based-on DPDK) > >> registers RTE_ETH_EVENT_INTR_RESET callback . > >> > >> Therefore, hope we build a recovery framework at the DPDK SDK level and be > >> compatible > >> with RTE_ETH_EVENT_INTR_RESET and RTE_ETH_EVENT_ERR_RECOVERING mechanism. > >> > >>> > >>>> > >>>>> > >>>>> > >>>>>>> > >>>>>>>>> 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 > >>>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>> > >>>>> > > > > . > >
