zcrx: rely on the returned refill q size

Kernel might decide to change the refill queue size and the user has to
recheck the size returned in struct io_uring_zcrx_ifq_reg::rq_entries.
Use the returned value instead of assuming RQ_ENTRIES.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

test/zcrx.c

@@ -23,7 +23,7 @@ static unsigned int ifidx, rxq;
 #define AREA_PAGES	132
 #define PAGE_SIZE	4096
 #define AREA_SZ		AREA_PAGES * PAGE_SIZE
-#define RQ_ENTRIES	64
+#define RQ_ENTRIES	128
 /* this is one more than the # of free pages after filling hw rxq */
 #define LOOP_COUNT	5
 #define DEV_ENV_VAR	"NETIF"
@@ -49,7 +49,7 @@ static int probe_zcrx(void *area)
 	struct io_uring_zcrx_ifq_reg reg = {
 		.if_idx = ifidx,
 		.if_rxq = rxq,
-		.rq_entries = 8,
+		.rq_entries = RQ_ENTRIES,
 		.area_ptr = (__u64)(unsigned long)&area_reg,
 	};
 	struct io_uring ring;
@@ -105,7 +105,7 @@ static int test_invalid_if(void *area)
 	struct io_uring_zcrx_ifq_reg reg = {
 		.if_idx = -1,
 		.if_rxq = rxq,
-		.rq_entries = 8,
+		.rq_entries = RQ_ENTRIES,
 		.area_ptr = (__u64)(unsigned long)&area_reg,
 	};
 
@@ -137,7 +137,7 @@ static int test_invalid_ifq_collision(void *area)
 	struct io_uring_zcrx_ifq_reg reg = {
 		.if_idx = ifidx,
 		.if_rxq = rxq,
-		.rq_entries = 8,
+		.rq_entries = RQ_ENTRIES,
 		.area_ptr = (__u64)(unsigned long)&area_reg,
 	};
 	int ret;
@@ -207,14 +207,14 @@ static int test_rq_setup(void *area)
 		return T_EXIT_FAIL;
 	}
 
-	reg.rq_entries = 7;
+	reg.rq_entries = RQ_ENTRIES - 1;
 	ret = try_register_ifq(&reg);
 	if (ret != 0) {
 		fprintf(stderr, "ifq registration failed %i\n", ret);
 		return T_EXIT_FAIL;
 	}
 
-	if (reg.rq_entries == 7) {
+	if (reg.rq_entries == RQ_ENTRIES - 1) {
 		fprintf(stderr, "registered non pow2 refill entries %i\n",
 			reg.rq_entries);
 		return T_EXIT_FAIL;
@@ -570,7 +570,7 @@ static void refill_garbage(struct recv_data *rd, uint64_t area_token)
 	rqe->off += AREA_SZ;
 	i++;
 
-	for (; i < RQ_ENTRIES; i++) {
+	for (; i < rq_ring->ring_entries; i++) {
 		rqe = get_refill_entry(rq_ring);
 		rqe->off = ((uint64_t)1 << IORING_ZCRX_AREA_SHIFT) - 1;
 	}