zdtm: add sk-unix-dgram-ghost test case

This testcase reproduces deadlock in "wait_fds_event" futex in open_fdinfos()
function (files subsystem).

Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>

test/zdtm/static/Makefile

@@ -381,6 +381,7 @@ TST_DIR		=				\
 		del_standalone_un		\
 		sk-unix-mntns			\
 		sk-unix01			\
+		sk-unix-dgram-ghost		\
 		unsupported_children_collision  \
 		shared_slave_mount_children	\
 		non_uniform_share_propagation	\

test/zdtm/static/sk-unix-dgram-ghost.c

@@ -0,0 +1,230 @@
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdbool.h>
+#include <limits.h>
+#include <errno.h>
+#include <dirent.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check data of bound ghost DGRAM unix socket and possibility to connect";
+const char *test_author	= "Alexander Mikhalitsyn <alexander@mihalicyn.com>";
+
+/*
+ * PROCESS_NUM | FREEZE_FREQ
+ * 3           | 1 / 5
+ * 4           | 1 / 5
+ * 5           | 2 / 5
+ * 10          | 10 / 10
+ */
+#define PROCESSES_NUM 10
+
+#define MSG "hello"
+char filename[PATH_MAX];
+char *dirname;
+TEST_OPTION(dirname, string, "directory name", 1);
+
+static int fill_sock_name(struct sockaddr_un *name, const char *filename)
+{
+	char *cwd;
+
+	cwd = get_current_dir_name();
+	if (strlen(filename) + strlen(cwd) + 1 >= sizeof(name->sun_path)) {
+		pr_err("Name %s/%s is too long for socket\n",
+		       cwd, filename);
+		return -1;
+	}
+
+	name->sun_family = AF_LOCAL;
+	ssprintf(name->sun_path, "%s/%s", cwd, filename);
+	return 0;
+}
+
+static int client(int i, task_waiter_t t)
+{
+	struct sockaddr_un addr;
+	int sk;
+
+	sk = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (sk < 0) {
+		pr_perror("open client %d", i);
+		return 1;
+	}
+
+	if (fill_sock_name(&addr, filename) < 0) {
+		pr_err("%s is too long for socket\n", filename);
+		return 1;
+	}
+
+	if (connect(sk, (struct sockaddr *) &addr, sizeof(struct sockaddr_un)) < 0) {
+		pr_perror("connect failed %d", i);
+		return 1;
+	}
+
+	/* we are ready to c/r */
+	task_waiter_complete(&t, 1);
+
+	/* wait for server let us to send data */
+	task_waiter_wait4(&t, 2);
+
+	test_msg("child %d: lets send\n", i);
+
+	if (send(sk, MSG, sizeof(MSG), 0) != sizeof(MSG)) {
+		pr_perror("send failed %d", i);
+		return 1;
+	}
+
+	test_msg("child %d: MSG was sent\n", i);
+
+	/* notify server that we sent data */
+	task_waiter_complete(&t, 3);
+
+	return 0;
+}
+
+static void child_exited(int signo)
+{
+	int status;
+	pid_t pid;
+
+	while (1) {
+		pid = waitpid(-1, &status, WNOHANG);
+		if (pid == -1) {
+			if (errno == ECHILD)
+				break;
+
+			fail("wait failed");
+			exit(1);
+		}
+
+		if (pid == 0)
+			return;
+
+		if (status) {
+			pr_err("A child (pid: %d) exited with 0x%x\n", pid, status);
+			exit(1);
+		}
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct sockaddr_un addr;
+	int srv, ret;
+	size_t i;
+	char buf[1024];
+	task_waiter_t t[PROCESSES_NUM];
+
+	test_init(argc, argv);
+
+	ssprintf(filename, "%s/%s", dirname, "sk");
+
+	if (fill_sock_name(&addr, filename) < 0) {
+		pr_err("%s is too long for socket\n", filename);
+		ret = 1;
+		goto clean;
+	}
+
+	if (signal(SIGCHLD, child_exited) == SIG_ERR) {
+		pr_perror("can't set SIGCHLD handler");
+		exit(1);
+	}
+
+	for (i = 0; i < PROCESSES_NUM; i++)
+		task_waiter_init(&t[i]);
+
+	if (mkdir(dirname, 0755) < 0) {
+		if (errno != EEXIST) {
+			pr_perror("Can't create %s", dirname);
+			return 1;
+		}
+	}
+
+	/*
+	 * Freeze happens if unix socket is the *last* file descriptor.
+	 * So, if we for example, move task_waiter_init() after server
+	 * socket creation we loose reproduce.
+	 */
+	srv = socket(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0);
+	if (srv < 0) {
+		pr_perror("open srv");
+		ret = 1;
+		goto clean;
+	}
+
+	if (bind(srv, (struct sockaddr *) &addr, sizeof(struct sockaddr_un))) {
+		pr_perror("bind srv");
+		ret = 1;
+		goto clean;
+	}
+
+	for (i = 0; i < PROCESSES_NUM; i++) {
+		ret = test_fork();
+		if (ret == -1) {
+			pr_perror("fork");
+			ret = 1;
+			goto clean;
+		}
+
+		if (ret == 0) {
+			close(srv);
+			exit(client(i, t[i]));
+		}
+
+		task_waiter_wait4(&t[i], 1);
+	}
+
+	/*
+	 * It's very important part of this test-case to make
+	 * *ghost* unix socket. Because problem with criu freeze
+	 * appears especially with *ghost* unix socket.
+	 */
+	unlink(addr.sun_path);
+
+	ret = 1;
+
+	test_daemon();
+	test_waitsig();
+
+	test_msg("C/R complete\n");
+
+	/* let childs to send data to server socket */
+	for (i = 0; i < PROCESSES_NUM; i++)
+		task_waiter_complete(&t[i], 2);
+
+	/* wait childs for send data */
+	for (i = 0; i < PROCESSES_NUM; i++)
+		task_waiter_wait4(&t[i], 3);
+
+	test_msg("Checking result\n");
+
+	/* check we can read all client messages */
+	for (i = 0; i < PROCESSES_NUM; i++) {
+		ret = read(srv, buf, sizeof(MSG));
+		buf[ret > 0 ? ret : 0] = 0;
+		if (ret != sizeof(MSG)) {
+			fail("%d: %s", ret, buf);
+			ret = 1;
+			goto clean;
+		}
+	}
+
+	ret = 0;
+	pass();
+
+clean:
+	unlink(addr.sun_path);
+	rmdir(dirname);
+	return ret;
+}

test/zdtm/static/sk-unix-dgram-ghost.desc

@@ -0,0 +1 @@
+{'flavor': 'h ns uns', 'flags': 'suid'}