libbpf: Replace size_t with __u32 in xsk interfaces

Replace size_t with __u32 in the xsk interfaces that contain this.
There is no reason to have size_t since the internal variable that
is manipulated is a __u32. The following APIs are affected:

__u32 xsk_ring_prod__reserve(struct xsk_ring_prod *prod, __u32 nb, __u32 *idx)
void xsk_ring_prod__submit(struct xsk_ring_prod *prod, __u32 nb)
__u32 xsk_ring_cons__peek(struct xsk_ring_cons *cons, __u32 nb, __u32 *idx)
void xsk_ring_cons__cancel(struct xsk_ring_cons *cons, __u32 nb)
void xsk_ring_cons__release(struct xsk_ring_cons *cons, __u32 nb)

The "nb" variable and the return values have been changed from size_t
to __u32.
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1606383455-8243-1-git-send-email-magnus.karlsson@gmail.com

tools/lib/bpf/xsk.h

@@ -113,8 +113,7 @@ static inline __u32 xsk_cons_nb_avail(struct xsk_ring_cons *r, __u32 nb)
 	return (entries > nb) ? nb : entries;
 }
 
-static inline size_t xsk_ring_prod__reserve(struct xsk_ring_prod *prod,
-					    size_t nb, __u32 *idx)
+static inline __u32 xsk_ring_prod__reserve(struct xsk_ring_prod *prod, __u32 nb, __u32 *idx)
 {
 	if (xsk_prod_nb_free(prod, nb) < nb)
 		return 0;
@@ -125,7 +124,7 @@ static inline size_t xsk_ring_prod__reserve(struct xsk_ring_prod *prod,
 	return nb;
 }
 
-static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
+static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, __u32 nb)
 {
 	/* Make sure everything has been written to the ring before indicating
 	 * this to the kernel by writing the producer pointer.
@@ -135,10 +134,9 @@ static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
 	*prod->producer += nb;
 }
 
-static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
-					 size_t nb, __u32 *idx)
+static inline __u32 xsk_ring_cons__peek(struct xsk_ring_cons *cons, __u32 nb, __u32 *idx)
 {
-	size_t entries = xsk_cons_nb_avail(cons, nb);
+	__u32 entries = xsk_cons_nb_avail(cons, nb);
 
 	if (entries > 0) {
 		/* Make sure we do not speculatively read the data before
@@ -153,13 +151,12 @@ static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
 	return entries;
 }
 
-static inline void xsk_ring_cons__cancel(struct xsk_ring_cons *cons,
-					 size_t nb)
+static inline void xsk_ring_cons__cancel(struct xsk_ring_cons *cons, __u32 nb)
 {
 	cons->cached_cons -= nb;
 }
 
-static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, size_t nb)
+static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, __u32 nb)
 {
 	/* Make sure data has been read before indicating we are done
 	 * with the entries by updating the consumer pointer.