fengchengwen <fengcheng...@huawei.com> writes:
> Hi all,
>
> This patch lasts for a long time. Are we waiting for 22.11 to deal with it?
That was my read, as can't reliably change the value of _MAX at this
stage without it having impact elsewhere.
> 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 <tho...@monjalon.net> writes:
>>
>>> 14/02/2022 11:16, Ray Kinsella:
>>>> Ray Kinsella <m...@ashroe.eu> writes:
>>>>> Thomas Monjalon <tho...@monjalon.net> writes:
>>>>>> 02/02/2022 12:44, Ray Kinsella:
>>>>>>> Ferruh Yigit <ferruh.yi...@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.
>>
>>
--
Regards, Ray K
