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

[Thomas Monjalon <thomas@monjalon.net>]

02/02/2022 12:44, Ray Kinsella:
> Ferruh Yigit <ferruh.yigit@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.

PS: I am not Cc'ed in this patchset,
so copying what I said on v6 (more than a year ago):
Please use the option --cc-cmd devtools/get-maintainer.sh