Re: [PATCH v1 bpf-next 11/11] bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.

This patch adds a test for BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.

Reviewed-by: Benjamin Herrenschmidt <redacted>
Signed-off-by: Kuniyuki Iwashima <redacted>
---
 .../bpf/prog_tests/migrate_reuseport.c        | 164 ++++++++++++++++++
 .../bpf/progs/test_migrate_reuseport_kern.c   |  54 ++++++
 2 files changed, 218 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/migrate_reuseport.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_migrate_reuseport_kern.c

diff --git a/tools/testing/selftests/bpf/prog_tests/migrate_reuseport.c b/tools/testing/selftests/bpf/prog_tests/migrate_reuseport.c
new file mode 100644
index 000000000000..87c72d9ccadd
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/migrate_reuseport.c

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Check if we can migrate child sockets.
+ *
+ *   1. call listen() for 5 server sockets.
+ *   2. update a map to migrate all child socket
+ *        to the last server socket (migrate_map[cookie] = 4)
+ *   3. call connect() for 25 client sockets.
+ *   4. call close() for first 4 server sockets.
+ *   5. call accept() for the last server socket.
+ *
+ * Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <linux/bpf.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#define NUM_SOCKS 5
+#define LOCALHOST "127.0.0.1"
+#define err_exit(condition, message)			      \
+	do {						      \
+		if (condition) {			      \
+			perror("ERROR: " message " ");	      \
+			exit(1);			      \
+		}					      \
+	} while (0)
+
+__u64 server_fds[NUM_SOCKS];
+int prog_fd, reuseport_map_fd, migrate_map_fd;
+
+
+void setup_bpf(void)
+{
+	struct bpf_object *obj;
+	struct bpf_program *prog;
+	struct bpf_map *reuseport_map, *migrate_map;
+	int err;
+
+	obj = bpf_object__open("test_migrate_reuseport_kern.o");
+	err_exit(libbpf_get_error(obj), "opening BPF object file failed");
+
+	err = bpf_object__load(obj);
+	err_exit(err, "loading BPF object failed");
+
+	prog = bpf_program__next(NULL, obj);
+	err_exit(!prog, "loading BPF program failed");
+
+	reuseport_map = bpf_object__find_map_by_name(obj, "reuseport_map");
+	err_exit(!reuseport_map, "loading BPF reuseport_map failed");
+
+	migrate_map = bpf_object__find_map_by_name(obj, "migrate_map");
+	err_exit(!migrate_map, "loading BPF migrate_map failed");
+
+	prog_fd = bpf_program__fd(prog);
+	reuseport_map_fd = bpf_map__fd(reuseport_map);
+	migrate_map_fd = bpf_map__fd(migrate_map);
+}
+
+void test_listen(void)
+{
+	struct sockaddr_in addr;
+	socklen_t addr_len = sizeof(addr);
+	int i, err, optval = 1, migrated_to = NUM_SOCKS - 1;
+	__u64 value;
+
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(80);
+	inet_pton(AF_INET, LOCALHOST, &addr.sin_addr.s_addr);
+
+	for (i = 0; i < NUM_SOCKS; i++) {
+		server_fds[i] = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+		err_exit(server_fds[i] == -1, "socket() for listener sockets failed");
+
+		err = setsockopt(server_fds[i], SOL_SOCKET, SO_REUSEPORT,
+				 &optval, sizeof(optval));
+		err_exit(err == -1, "setsockopt() for SO_REUSEPORT failed");
+
+		if (i == 0) {
+			err = setsockopt(server_fds[i], SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF,
+					 &prog_fd, sizeof(prog_fd));
+			err_exit(err == -1, "setsockopt() for SO_ATTACH_REUSEPORT_EBPF failed");
+		}
+
+		err = bind(server_fds[i], (struct sockaddr *)&addr, addr_len);
+		err_exit(err == -1, "bind() failed");
+
+		err = listen(server_fds[i], 32);
+		err_exit(err == -1, "listen() failed");
+
+		err = bpf_map_update_elem(reuseport_map_fd, &i, &server_fds[i], BPF_NOEXIST);
+		err_exit(err == -1, "updating BPF reuseport_map failed");
+
+		err = bpf_map_lookup_elem(reuseport_map_fd, &i, &value);
+		err_exit(err == -1, "looking up BPF reuseport_map failed");
+
+		printf("fd[%d] (cookie: %llu) -> fd[%d]\n", i, value, migrated_to);
+		err = bpf_map_update_elem(migrate_map_fd, &value, &migrated_to, BPF_NOEXIST);
+		err_exit(err == -1, "updating BPF migrate_map failed");
+	}
+}
+
+void test_connect(void)
+{
+	struct sockaddr_in addr;
+	socklen_t addr_len = sizeof(addr);
+	int i, err, client_fd;
+
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(80);
+	inet_pton(AF_INET, LOCALHOST, &addr.sin_addr.s_addr);
+
+	for (i = 0; i < NUM_SOCKS * 5; i++) {
+		client_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+		err_exit(client_fd == -1, "socket() for listener sockets failed");
+
+		err = connect(client_fd, (struct sockaddr *)&addr, addr_len);
+		err_exit(err == -1, "connect() failed");
+
+		close(client_fd);
+	}
+}
+
+void test_close(void)
+{
+	int i;
+
+	for (i = 0; i < NUM_SOCKS - 1; i++)
+		close(server_fds[i]);
+}
+
+void test_accept(void)
+{
+	struct sockaddr_in addr;
+	socklen_t addr_len = sizeof(addr);
+	int cnt, client_fd;
+
+	fcntl(server_fds[NUM_SOCKS - 1], F_SETFL, O_NONBLOCK);
+
+	for (cnt = 0; cnt < NUM_SOCKS * 5; cnt++) {
+		client_fd = accept(server_fds[NUM_SOCKS - 1], (struct sockaddr *)&addr, &addr_len);
+		err_exit(client_fd == -1, "accept() failed");
+	}
+
+	printf("%d accepted, %d is expected\n", cnt, NUM_SOCKS * 5);
+}
+
+int main(void)