On Mon, Mar 6, 2023 at 3:00 AM Ferruh Yigit wrote: > > 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? +1 on the overall approach. > > > >> > >>>> 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.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 > >>>>> > >>>> > >>> > > >