On Tue, Jun 28, 2022 at 04:46:43PM +0200, David Marchand wrote:
> Make rte_bus opaque for non internal users.
> This will make extending this object possible without breaking the ABI.
>
> Introduce a new driver header and move rte_bus definition and helpers.
>
> Signed-off-by: David Marchand <david.march...@redhat.com>
> ---
... snip ...
> -struct rte_bus {
> - RTE_TAILQ_ENTRY(rte_bus) next; /**< Next bus object in linked list */
> - const char *name; /**< Name of the bus */
> - rte_bus_scan_t scan; /**< Scan for devices attached to bus */
> - rte_bus_probe_t probe; /**< Probe devices on bus */
> - rte_bus_find_device_t find_device; /**< Find a device on the bus */
> - rte_bus_plug_t plug; /**< Probe single device for drivers */
> - rte_bus_unplug_t unplug; /**< Remove single device from driver */
> - rte_bus_parse_t parse; /**< Parse a device name */
> - rte_bus_devargs_parse_t devargs_parse; /**< Parse bus devargs */
> - rte_dev_dma_map_t dma_map; /**< DMA map for device in the bus */
> - rte_dev_dma_unmap_t dma_unmap; /**< DMA unmap for device in the bus */
> - struct rte_bus_conf conf; /**< Bus configuration */
> - rte_bus_get_iommu_class_t get_iommu_class; /**< Get iommu class */
> - rte_dev_iterate_t dev_iterate; /**< Device iterator. */
> - rte_bus_hot_unplug_handler_t hot_unplug_handler;
> - /**< handle hot-unplug failure on the bus */
> - rte_bus_sigbus_handler_t sigbus_handler;
> - /**< handle sigbus error on the bus */
> -
> -};
since we're overhauling anyway we could follow suit with a number of the
lessons from posix apis e.g. pthread and eliminate typed pointers for a
little extra value.
> +struct rte_bus;
> +struct rte_device;
to avoid people tripping over mishandling pointers in/out of the api
surface taking the opaque object you could declare opaque handle for the
api to operate on instead. it would force the use of a cast in the
implementation but would avoid accidental void * of the wrong thing that
got cached being passed in. if the cast was really undesirable just
whack it under an inline / internal function.
e.g. make the opaque object an explicit type.
struct {
uintptr_t opaque;
} rte_bus_handle_t;
// implementation
rte_bus_handle_t
rte_bus_find(rte_bus_handle_t start,
rte_bus_cmp_t cmp, const void *data)
{
struct rte_bus *bus = (struct rte_bus *)start.opaque;
// do bus things on bus
return {.opaque = whatever};
}
then you will get hard compile time failure if someone messes up
argument passing.
e.g.
void *somerandomp = ...;
...
rte_bus_find(somerandomp, ...); // compile fail
i would actually suggest this wrapping in a struct / handle approach for
any opaque object that is passed over the api surface. the change is
bigger of course...
it has various other advantages when/if we decide to make the bus/driver
surface stable in abi which i understand is not a promise dpdk makes
right now but still we might one day.
anyway, just a suggestion. i like the series either way.
