[dpdk-dev] [PATCH v7 1/4] ethdev: support device reset and recovery events

[fengchengwen]

Hi all,

  This patch lasts for a long time. Are we waiting for 22.11 to deal with it?

  We have the same requirements for the reset or recovery mechanism, but there are differences:

    APP                                    PMD
     |                                      |
     |                                  detect error
     |     <---report error event---        |
     |                                      |
do error stats                              |
and report                                  |
     |      ---start recover-->             |
     |                                  do recover
     |     <---report recover result        |
     |                                      |
if succ just log
else may migrate
service

Can we generalize these processes(means that the implementation is at the framework layer)? or only at PMD API?


On 2022/2/15 0:06, Ray Kinsella wrote:
> 
> Thomas Monjalon <thomas at monjalon.net> writes:
> 
>> 14/02/2022 11:16, Ray Kinsella:
>>> Ray Kinsella <mdr at ashroe.eu> writes:
>>>> Thomas Monjalon <thomas at monjalon.net> writes:
>>>>> 02/02/2022 12:44, Ray Kinsella:
>>>>>> Ferruh Yigit <ferruh.yigit at intel.com> writes:
>>>>>>> On 1/28/2022 12:48 PM, Kalesh A P wrote:
>>>>>>>> --- a/lib/ethdev/rte_ethdev.h
>>>>>>>> +++ b/lib/ethdev/rte_ethdev.h
>>>>>>>> @@ -3818,6 +3818,24 @@ enum rte_eth_event_type {
>>>>>>>>   	RTE_ETH_EVENT_DESTROY,  /**< port is released */
>>>>>>>>   	RTE_ETH_EVENT_IPSEC,    /**< IPsec offload related event */
>>>>>>>>   	RTE_ETH_EVENT_FLOW_AGED,/**< New aged-out flows is detected */
>>>>>>>> +	RTE_ETH_EVENT_ERR_RECOVERING,
>>>>>>>> +			/**< port recovering from an error
>>>>>>>> +			 *
>>>>>>>> +			 * PMD detected a FW reset or error condition.
>>>>>>>> +			 * PMD will try to recover from the error.
>>>>>>>> +			 * Data path may be quiesced and Control path operations
>>>>>>>> +			 * may fail at this time.
>>>>>>>> +			 */
>>>>>>>> +	RTE_ETH_EVENT_RECOVERED,
>>>>>>>> +			/**< port recovered from an error
>>>>>>>> +			 *
>>>>>>>> +			 * PMD has recovered from the error condition.
>>>>>>>> +			 * Control path and Data path are up now.
>>>>>>>> +			 * PMD re-configures the port to the state prior to the error.
>>>>>>>> +			 * Since the device has undergone a reset, flow rules
>>>>>>>> +			 * offloaded prior to reset may be lost and
>>>>>>>> +			 * the application should recreate the rules again.
>>>>>>>> +			 */
>>>>>>>>   	RTE_ETH_EVENT_MAX       /**< max value of this enum */
>>>>>>>
>>>>>>>
>>>>>>> Also ABI check complains about 'RTE_ETH_EVENT_MAX' value check, cc'ed more people
>>>>>>> to evaluate if it is a false positive:
>>>>>>>
>>>>>>>
>>>>>>> 1 function with some indirect sub-type change:
>>>>>>>   [C] 'function int rte_eth_dev_callback_register(uint16_t, rte_eth_event_type, rte_eth_dev_cb_fn, void*)' at rte_ethdev.c:4637:1 has some indirect sub-type changes:
>>>>>>>     parameter 3 of type 'typedef rte_eth_dev_cb_fn' has sub-type changes:
>>>>>>>       underlying type 'int (typedef uint16_t, enum rte_eth_event_type, void*, void*)*' changed:
>>>>>>>         in pointed to type 'function type int (typedef uint16_t, enum rte_eth_event_type, void*, void*)':
>>>>>>>           parameter 2 of type 'enum rte_eth_event_type' has sub-type changes:
>>>>>>>             type size hasn't changed
>>>>>>>             2 enumerator insertions:
>>>>>>>               'rte_eth_event_type::RTE_ETH_EVENT_ERR_RECOVERING' value '11'
>>>>>>>               'rte_eth_event_type::RTE_ETH_EVENT_RECOVERED' value '12'
>>>>>>>             1 enumerator change:
>>>>>>>               'rte_eth_event_type::RTE_ETH_EVENT_MAX' from value '11' to '13' at rte_ethdev.h:3807:1
>>>>>>
>>>>>> I don't immediately see the problem that this would cause.
>>>>>> There are no array sizes etc dependent on the value of MAX for instance.
>>>>>>
>>>>>> Looks safe?
>>>>>
>>>>> We never know how this enum will be used by the application.
>>>>> The max value may be used for the size of an event array.
>>>>> It looks a real ABI issue unfortunately.
>>>>
>>>> Right - but we only really care about it when an array size based on MAX
>>>> is likely to be passed to DPDK, which doesn't apply in this case.
>>
>> I don't completely agree.
>> A developer may assume an event will never exceed MAX value.
>> However, after an upgrade of DPDK without app rebuild,
>> a higher event value may be received in the app,
>> breaking the assumption.
>> Should we consider this case as an ABI breakage?
> 
> Nope - I think we should explicitly exclude MAX values from any
> ABI guarantee, as being able to change them is key to our be able to
> evolve DPDK while maintaining ABI stability. 
> 
> Consider what it means applying the ABI policy to a MAX value, you are
> in effect saying that that no value can be added to this enumeration
> until the next ABI version, for me this is very restrictive without a
> solid reason. 
> 
>>
>>>> I noted that some Linux folks explicitly mark similar MAX values as not
>>>> part of the ABI.
>>>>
>>>> /usr/include/linux/perf_event.h
>>>> 37:     PERF_TYPE_MAX,                          /* non-ABI */
>>>> 60:     PERF_COUNT_HW_MAX,                      /* non-ABI */
>>>> 79:     PERF_COUNT_HW_CACHE_MAX,                /* non-ABI */
>>>> 87:     PERF_COUNT_HW_CACHE_OP_MAX,             /* non-ABI */
>>>> 94:     PERF_COUNT_HW_CACHE_RESULT_MAX,         /* non-ABI */
>>>> 116:    PERF_COUNT_SW_MAX,                      /* non-ABI */
>>>> 149:    PERF_SAMPLE_MAX = 1U << 24,             /* non-ABI */
>>>> 151:    __PERF_SAMPLE_CALLCHAIN_EARLY           = 1ULL << 63, /*
>>>> non-ABI; internal use */
>>>> 189:    PERF_SAMPLE_BRANCH_MAX_SHIFT            /* non-ABI */
>>>> 267:    PERF_TXN_MAX            = (1 << 8), /* non-ABI */
>>>> 301:    PERF_FORMAT_MAX = 1U << 4,              /* non-ABI */
>>>> 1067:   PERF_RECORD_MAX,                        /* non-ABI */
>>>> 1078:   PERF_RECORD_KSYMBOL_TYPE_MAX            /* non-ABI */
>>>> 1087:   PERF_BPF_EVENT_MAX,             /* non-ABI */
>>>
>>> Any thoughts on similarly annotating all our _MAX enums in the same way?
>>> We could also add a section in the ABI Policy to make it explicit _MAX
>>> enum values are not part of the ABI - what do folks think?
>>
>> Interesting. I am not sure it is always ABI-safe though.
> 
>