selftests: xsk: Simplify the retry code

Simplify the retry code and make it more efficient by waiting first,
instead of trying immediately which always fails due to the
asynchronous nature of xsk socket close. Also decrease the wait time
to significantly lower the run-time of the test suite.
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210825093722.10219-6-magnus.karlsson@gmail.com

tools/testing/selftests/bpf/xdpxceiver.c

@@ -745,24 +745,19 @@ static void thread_common_ops(struct ifobject *ifobject, void *bufs)
 	if (bufs == MAP_FAILED)
 		exit_with_error(errno);
 
-	xsk_configure_umem(ifobject, bufs, 0);
-	ifobject->umem = ifobject->umem_arr[0];
-	ret = xsk_configure_socket(ifobject, 0);
-
-	/* Retry Create Socket if it fails as xsk_socket__create()
-	 * is asynchronous
-	 */
-	while (ret && ctr < SOCK_RECONF_CTR) {
+	while (ctr++ < SOCK_RECONF_CTR) {
 		xsk_configure_umem(ifobject, bufs, 0);
 		ifobject->umem = ifobject->umem_arr[0];
 		ret = xsk_configure_socket(ifobject, 0);
+		if (!ret)
+			break;
+
+		/* Retry Create Socket if it fails as xsk_socket__create() is asynchronous */
 		usleep(USLEEP_MAX);
-		ctr++;
+		if (ctr >= SOCK_RECONF_CTR)
+			exit_with_error(-ret);
 	}
 
-	if (ctr >= SOCK_RECONF_CTR)
-		exit_with_error(ret);
-
 	ifobject->umem = ifobject->umem_arr[0];
 	ifobject->xsk = ifobject->xsk_arr[0];
 
@@ -1125,8 +1120,10 @@ int main(int argc, char **argv)
 	ksft_set_plan(TEST_MODE_MAX * TEST_TYPE_MAX);
 
 	for (i = 0; i < TEST_MODE_MAX; i++) {
-		for (j = 0; j < TEST_TYPE_MAX; j++)
+		for (j = 0; j < TEST_TYPE_MAX; j++) {
 			run_pkt_test(i, j);
+			usleep(USLEEP_MAX);
+		}
 	}
 
 cleanup:

tools/testing/selftests/bpf/xdpxceiver.h

@@ -35,7 +35,7 @@
 #define UDP_PKT_SIZE (IP_PKT_SIZE - sizeof(struct iphdr))
 #define UDP_PKT_DATA_SIZE (UDP_PKT_SIZE - sizeof(struct udphdr))
 #define EOT (-1)
-#define USLEEP_MAX 200000
+#define USLEEP_MAX 10000
 #define SOCK_RECONF_CTR 10
 #define BATCH_SIZE 64
 #define POLL_TMOUT 1000