[dpdk-dev] The mbuf API needs some cleaning up

["Morten Brørup" <mb@smartsharesystems.com>]

The MBUF library exposes some macros and constants without the RTE_ prefix. I propose cleaning up these, so better names get into the coming LTS release.

The worst is:
#define MBUF_INVALID_PORT UINT16_MAX

I say it's the worst because when we were looking for the official "invalid" port value for our application, we didn't find this one. (Probably because its documentation is wrong.)

MBUF_INVALID_PORT is defined in rte_mbuf_core.h without any description, and in rte_mbuf.h, where it is injected between the rte_pktmbuf_reset() function and its description, so the API documentation shows the function's description for the constant, and no description for the function.

I propose keeping it at a sensible location in rte_mbuf_core.h only, adding a description, and renaming it to:
#define RTE_PORT_INVALID UINT16_MAX

For backwards compatibility, we could add:
/* this old name is deprecated */
#define MBUF_INVALID_PORT RTE_PORT_INVALID

I also wonder why there are no compiler warnings about the double definition?


There are also the data buffer location constants:
#define EXT_ATTACHED_MBUF    (1ULL << 61)
and
#define IND_ATTACHED_MBUF    (1ULL << 62)

There are already macros (with good names) for reading these, so simply adding the RTE_ prefix to these two constants suffices.


And all the packet offload flags, such as:
#define PKT_RX_VLAN          (1ULL << 0)

They are supposed to be used by applications, so I guess we should keep them unchanged for ABI stability reasons.


And the local macro:
#define MBUF_RAW_ALLOC_CHECK(m) do { \

This might as well be an internal inline function:
/* internal */
static inline void
__rte_mbuf_raw_alloc_check(const struct rte_mbuf *m)

Or we could keep it a macro and move it next to
__rte_mbuf_sanity_check(), keeping it clear that it is only relevant when RTE_LIBRTE_MBUF_DEBUG is set. But rename it to lower case, similar to the __rte_mbuf_sanity_check() macro.


Med venlig hilsen / kind regards
- Morten Brørup