[PATCH liburing v2 02/12] t/poll-link: Don't brute force the port number

[Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>]

From: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>

Don't brute force the port number, use `t_bind_ephemeral_port()`,
much simpler and reliable for choosing a port number that is not
in use.

v2:
  - While in there, fix variable placements (put them at the top).

Cc: Dylan Yudaken <dylany@xxxxxx>
Cc: Facebook Kernel Team <kernel-team@xxxxxx>
Cc: Pavel Begunkov <asml.silence@xxxxxxxxx>
Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx>
Tested-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx>
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
---
 test/poll-link.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/test/poll-link.c b/test/poll-link.c
index 197ad77..39b48f5 100644
--- a/test/poll-link.c
+++ b/test/poll-link.c
@@ -9,14 +9,15 @@
 #include <pthread.h>
 #include <sys/socket.h>
 #include <netinet/tcp.h>
 #include <netinet/in.h>
 #include <poll.h>
 #include <arpa/inet.h>
 
+#include "helpers.h"
 #include "liburing.h"
 
 pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 
 static int recv_thread_ready = 0;
 static int recv_thread_done = 0;
@@ -46,36 +47,37 @@ struct data {
 	unsigned short port;
 	unsigned int addr;
 	int stop;
 };
 
 static void *send_thread(void *arg)
 {
+	struct sockaddr_in addr;
 	struct data *data = arg;
+	int s0;
 
 	wait_for_var(&recv_thread_ready);
 
-	int s0 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	s0 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 	assert(s0 != -1);
 
-	struct sockaddr_in addr;
-
 	addr.sin_family = AF_INET;
 	addr.sin_port = data->port;
 	addr.sin_addr.s_addr = data->addr;
 
 	if (connect(s0, (struct sockaddr*)&addr, sizeof(addr)) != -1)
 		wait_for_var(&recv_thread_done);
 
 	close(s0);
 	return 0;
 }
 
 void *recv_thread(void *arg)
 {
+	struct sockaddr_in addr = { };
 	struct data *data = arg;
 	struct io_uring_sqe *sqe;
 	struct io_uring ring;
 	int i, ret;
 
 	ret = io_uring_queue_init(8, &ring, 0);
 	assert(ret == 0);
@@ -85,35 +87,25 @@ void *recv_thread(void *arg)
 
 	int32_t val = 1;
 	ret = setsockopt(s0, SOL_SOCKET, SO_REUSEPORT, &val, sizeof(val));
 	assert(ret != -1);
 	ret = setsockopt(s0, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 	assert(ret != -1);
 
-	struct sockaddr_in addr;
-
 	addr.sin_family = AF_INET;
 	data->addr = inet_addr("127.0.0.1");
 	addr.sin_addr.s_addr = data->addr;
 
-	i = 0;
-	do {
-		data->port = htons(1025 + (rand() % 64510));
-		addr.sin_port = data->port;
-
-		if (bind(s0, (struct sockaddr*)&addr, sizeof(addr)) != -1)
-			break;
-	} while (++i < 100);
-
-	if (i >= 100) {
-		fprintf(stderr, "Can't find good port, skipped\n");
+	if (t_bind_ephemeral_port(s0, &addr)) {
+		perror("bind");
 		data->stop = 1;
 		signal_var(&recv_thread_ready);
-		goto out;
+		goto err;
 	}
+	data->port = addr.sin_port;
 
 	ret = listen(s0, 128);
 	assert(ret != -1);
 
 	signal_var(&recv_thread_ready);
 
 	sqe = io_uring_get_sqe(&ring);
@@ -154,15 +146,14 @@ void *recv_thread(void *arg)
 					(uint64_t) cqe->user_data, cqe->res,
 					data->expected[idx]);
 			goto err;
 		}
 		io_uring_cqe_seen(&ring, cqe);
 	}
 
-out:
 	signal_var(&recv_thread_done);
 	close(s0);
 	io_uring_queue_exit(&ring);
 	return NULL;
 err:
 	signal_var(&recv_thread_done);
 	close(s0);
-- 
Ammar Faizi