selftests/bpf: Add struct send_recv_arg

Avoid setting total_bytes and stop as global variables, this patch adds
a new struct named send_recv_arg to pass arguments between threads. Put
these two variables together with fd into this struct and pass it to
server thread, so that server thread can access these two variables without
setting them as global ones.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/ca1dd703b796f6810985418373e750f7068b4186.1712813933.git.tanggeliang@kylinos.cnSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c

@@ -21,7 +21,6 @@
 
 static const unsigned int total_bytes = 10 * 1024 * 1024;
 static int expected_stg = 0xeB9F;
-static int stop;
 
 static int settcpca(int fd, const char *tcp_ca)
 {
@@ -34,13 +33,20 @@ static int settcpca(int fd, const char *tcp_ca)
 	return 0;
 }
 
+struct send_recv_arg {
+	int		fd;
+	uint32_t	bytes;
+	int		stop;
+};
+
 static void *server(void *arg)
 {
-	int lfd = (int)(long)arg, err = 0, fd;
+	struct send_recv_arg *a = (struct send_recv_arg *)arg;
 	ssize_t nr_sent = 0, bytes = 0;
 	char batch[1500];
+	int err = 0, fd;
 
-	fd = accept(lfd, NULL, NULL);
+	fd = accept(a->fd, NULL, NULL);
 	while (fd == -1) {
 		if (errno == EINTR)
 			continue;
@@ -53,9 +59,9 @@ static void *server(void *arg)
 		goto done;
 	}
 
-	while (bytes < total_bytes && !READ_ONCE(stop)) {
+	while (bytes < a->bytes && !READ_ONCE(a->stop)) {
 		nr_sent = send(fd, &batch,
-			       MIN(total_bytes - bytes, sizeof(batch)), 0);
+			       MIN(a->bytes - bytes, sizeof(batch)), 0);
 		if (nr_sent == -1 && errno == EINTR)
 			continue;
 		if (nr_sent == -1) {
@@ -65,13 +71,13 @@ static void *server(void *arg)
 		bytes += nr_sent;
 	}
 
-	ASSERT_EQ(bytes, total_bytes, "send");
+	ASSERT_EQ(bytes, a->bytes, "send");
 
 done:
 	if (fd >= 0)
 		close(fd);
 	if (err) {
-		WRITE_ONCE(stop, 1);
+		WRITE_ONCE(a->stop, 1);
 		return ERR_PTR(err);
 	}
 	return NULL;
@@ -80,18 +86,22 @@ static void *server(void *arg)
 static void do_test(const char *tcp_ca, const struct bpf_map *sk_stg_map)
 {
 	ssize_t nr_recv = 0, bytes = 0;
+	struct send_recv_arg arg = {
+		.bytes	= total_bytes,
+		.stop	= 0,
+	};
 	int lfd = -1, fd = -1;
 	pthread_t srv_thread;
 	void *thread_ret;
 	char batch[1500];
 	int err;
 
-	WRITE_ONCE(stop, 0);
-
 	lfd = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
 	if (!ASSERT_NEQ(lfd, -1, "socket"))
 		return;
 
+	arg.fd = lfd;
+
 	fd = socket(AF_INET6, SOCK_STREAM, 0);
 	if (!ASSERT_NEQ(fd, -1, "socket")) {
 		close(lfd);
@@ -123,12 +133,12 @@ static void do_test(const char *tcp_ca, const struct bpf_map *sk_stg_map)
 			goto done;
 	}
 
-	err = pthread_create(&srv_thread, NULL, server, (void *)(long)lfd);
+	err = pthread_create(&srv_thread, NULL, server, (void *)&arg);
 	if (!ASSERT_OK(err, "pthread_create"))
 		goto done;
 
 	/* recv total_bytes */
-	while (bytes < total_bytes && !READ_ONCE(stop)) {
+	while (bytes < total_bytes && !READ_ONCE(arg.stop)) {
 		nr_recv = recv(fd, &batch,
 			       MIN(total_bytes - bytes, sizeof(batch)), 0);
 		if (nr_recv == -1 && errno == EINTR)
@@ -140,7 +150,7 @@ static void do_test(const char *tcp_ca, const struct bpf_map *sk_stg_map)
 
 	ASSERT_EQ(bytes, total_bytes, "recv");
 
-	WRITE_ONCE(stop, 1);
+	WRITE_ONCE(arg.stop, 1);
 	pthread_join(srv_thread, &thread_ret);
 	ASSERT_OK(IS_ERR(thread_ret), "thread_ret");