Re: [dpdk-dev] [PATCH v4 7/9] eal: add lcore init callbacks

[Olivier Matz <olivier.matz@6wind.com>]

On Fri, Jun 26, 2020 at 04:47:34PM +0200, David Marchand wrote:
> DPDK components and applications can have their say when a new lcore is
> initialized. For this, they can register a callback for initializing and
> releasing their private data.
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>

[...]

> +/**
> + * Register callbacks invoked when initializing and uninitializing a lcore.
> + *
> + * This function calls the init callback with all initialized lcores.
> + * Any error reported by the init callback triggers a rollback calling the
> + * uninit callback for each lcore.
> + * If this step succeeds, the callbacks are put in the lcore callbacks list
> + * that will get called for each lcore allocation/release.
> + *
> + * Note: callbacks execution is serialised under a lock protecting the lcores
> + * and callbacks list.
> + *
> + * @param name
> + *   A name serving as a small description for this callback.
> + * @param init
> + *   The callback invoked when a lcore_id is initialized.
> + * @param uninit
> + *   The callback invoked when a lcore_id is uninitialized.

nit: it could be highlighted that init or uninit can be NULL.

> + * @param arg
> + *   An optional argument that gets passed to the callback when it gets
> + *   invoked.
> + * @return
> + *   On success, returns an opaque pointer for the registered object.
> + *   On failure (either memory allocation issue in the function itself or an
> + *   error is returned by the init callback itself), returns NULL.
> + */
> +__rte_experimental
> +void *
> +rte_lcore_callback_register(const char *name, rte_lcore_init_cb init,
> +	rte_lcore_uninit_cb uninit, void *arg);