xdp_ddos01_blacklist_cmdline: Fix wrong usage of bpf_map_get_next_key

commit 83efebc missed another wrong usage of bpf_map_get_next_key.

Signed-off-by: Jesper Dangaard Brouer <[email protected]>

kernel/samples/bpf/xdp_ddos01_blacklist_cmdline.c

@@ -248,12 +248,12 @@ static void blacklist_list_all_ipv4(int fd)
 
 static void blacklist_list_all_ports(int portfd, int countfds[])
 {
-	__u32 key = 0, next_key;
+	__u32 key, *prev_key = NULL;
 	__u64 value;
 	bool started = false;
 
 	/* printf("{\n"); */
-	while (bpf_map_get_next_key(portfd, &key, &next_key) == 0) {
+	while (bpf_map_get_next_key(portfd, prev_key, &key) == 0) {
 		if ((bpf_map_lookup_elem(portfd, &key, &value)) != 0) {
 			fprintf(stderr,
 				"ERR: bpf_map_lookup_elem(%d) failed key:0x%X\n", portfd, key);
@@ -264,7 +264,7 @@ static void blacklist_list_all_ports(int portfd, int countfds[])
 			started = true;
 			blacklist_print_port(key, value, countfds);
 		}
-		key = next_key;
+		prev_key = &key;
 	}
 }