[RFC PATCH] cryptodev: add return parameter to callback process API

[Thomas Monjalon]

24/06/2022 14:12, Srujana Challa:
> Adds a return parameter "uint16_t qp_id" to the functions
> rte_cryptodev_pmd_callback_process and rte_cryptodev_cb_fn.
> The new parameter is used to return queue pair ID to
> the application when it gets error interrupt, so that
> application can disable and enable the queue pair, to bring
> the queue back to normal state.

What about other events?

> + * @param	qp_id	Return parameter from driver to the application. Driver
> + *			returns queue pair ID when it gets HW error interrupt.
> + *			The application can release and setup the queue
> + *			again, to bring the HW queue back to normal state.

What will it mean if the event is not related to queues?

>   * @param	event	Crypto device event to register for notification of.
>   * @param	cb_arg	User specified parameter to be passed as to passed to
>   *			users callback function.

Are you going to add a new callback parameter each time
the application needs info about a new event?

In my opinion, it is a very bad idea.
As done in ethdev, you should add a query function specific to the event.

Example: https://git.dpdk.org/dpdk/commit/?id=bc70e5594838
Here, when a threshold is reached, an event RTE_ETH_EVENT_RX_AVAIL_THRESH
is fired, and the application can get more info about what happened
by calling the function rte_eth_rx_avail_thresh_query().
Look at the parameters description:
"
@param[inout] queue_id
 On input starting Rx queue index to search from.
 If the queue_id is bigger than maximum queue ID of the port,
 search is started from 0. So that application can keep calling
 this function to handle all pending events with a simple increment
 of queue_id on the next call.
 On output if return value is 1, Rx queue index with the event pending.
@param[out] avail_thresh
 Location for available descriptors threshold of the found Rx queue.
"