Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

16 files changed, 4548 insertions, 0 deletions

diff --git a/tools/testing/selftests/filesystems/.gitignore b/tools/testing/selftests/filesystems/.gitignore
new file mode 100644
index 000000000..f0c0ff20d
--- /dev/null
+++ b/tools/testing/selftests/filesystems/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+dnotify_test
+devpts_pts
diff --git a/tools/testing/selftests/filesystems/Makefile b/tools/testing/selftests/filesystems/Makefile
new file mode 100644
index 000000000..c647fd6a0
--- /dev/null
+++ b/tools/testing/selftests/filesystems/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += $(KHDR_INCLUDES)
+TEST_GEN_PROGS := devpts_pts
+TEST_GEN_PROGS_EXTENDED := dnotify_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/filesystems/binderfs/.gitignore b/tools/testing/selftests/filesystems/binderfs/.gitignore
new file mode 100644
index 000000000..8e5cf9084
--- /dev/null
+++ b/tools/testing/selftests/filesystems/binderfs/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+binderfs_test
diff --git a/tools/testing/selftests/filesystems/binderfs/Makefile b/tools/testing/selftests/filesystems/binderfs/Makefile
new file mode 100644
index 000000000..c2f7cef91
--- /dev/null
+++ b/tools/testing/selftests/filesystems/binderfs/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += $(KHDR_INCLUDES) -pthread
+TEST_GEN_PROGS := binderfs_test
+
+binderfs_test: binderfs_test.c ../../kselftest.h ../../kselftest_harness.h
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
new file mode 100644
index 000000000..5f362c0fd
--- /dev/null
+++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
@@ -0,0 +1,540 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/fsuid.h>
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/sysinfo.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <linux/android/binder.h>
+#include <linux/android/binderfs.h>
+
+#include "../../kselftest_harness.h"
+
+#define DEFAULT_THREADS 4
+
+#define PTR_TO_INT(p) ((int)((intptr_t)(p)))
+#define INT_TO_PTR(u) ((void *)((intptr_t)(u)))
+
+#define close_prot_errno_disarm(fd) \
+	if (fd >= 0) {              \
+		int _e_ = errno;    \
+		close(fd);          \
+		errno = _e_;        \
+		fd = -EBADF;        \
+	}
+
+static void change_mountns(struct __test_metadata *_metadata)
+{
+	int ret;
+
+	ret = unshare(CLONE_NEWNS);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to unshare mount namespace",
+			strerror(errno));
+	}
+
+	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to mount / as private",
+			strerror(errno));
+	}
+}
+
+static int __do_binderfs_test(struct __test_metadata *_metadata)
+{
+	int fd, ret, saved_errno, result = 1;
+	size_t len;
+	ssize_t wret;
+	struct binderfs_device device = { 0 };
+	struct binder_version version = { 0 };
+	char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
+		device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
+	static const char * const binder_features[] = {
+		"oneway_spam_detection",
+		"extended_error",
+	};
+
+	change_mountns(_metadata);
+
+	EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
+		TH_LOG("%s - Failed to create binderfs mountpoint",
+			strerror(errno));
+		goto out;
+	}
+
+	ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
+	EXPECT_EQ(ret, 0) {
+		if (errno == ENODEV)
+			SKIP(goto out, "binderfs missing");
+		TH_LOG("%s - Failed to mount binderfs", strerror(errno));
+		goto rmdir;
+	}
+
+	/* success: binderfs mounted */
+
+	memcpy(device.name, "my-binder", strlen("my-binder"));
+
+	snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
+	fd = open(device_path, O_RDONLY | O_CLOEXEC);
+	EXPECT_GE(fd, 0) {
+		TH_LOG("%s - Failed to open binder-control device",
+			strerror(errno));
+		goto umount;
+	}
+
+	ret = ioctl(fd, BINDER_CTL_ADD, &device);
+	saved_errno = errno;
+	close(fd);
+	errno = saved_errno;
+	EXPECT_GE(ret, 0) {
+		TH_LOG("%s - Failed to allocate new binder device",
+			strerror(errno));
+		goto umount;
+	}
+
+	TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
+		device.major, device.minor, device.name);
+
+	/* success: binder device allocation */
+
+	snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
+	fd = open(device_path, O_CLOEXEC | O_RDONLY);
+	EXPECT_GE(fd, 0) {
+		TH_LOG("%s - Failed to open my-binder device",
+			strerror(errno));
+		goto umount;
+	}
+
+	ret = ioctl(fd, BINDER_VERSION, &version);
+	saved_errno = errno;
+	close(fd);
+	errno = saved_errno;
+	EXPECT_GE(ret, 0) {
+		TH_LOG("%s - Failed to open perform BINDER_VERSION request",
+			strerror(errno));
+		goto umount;
+	}
+
+	TH_LOG("Detected binder version: %d", version.protocol_version);
+
+	/* success: binder transaction with binderfs binder device */
+
+	ret = unlink(device_path);
+	EXPECT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to delete binder device",
+			strerror(errno));
+		goto umount;
+	}
+
+	/* success: binder device removal */
+
+	snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
+	ret = unlink(device_path);
+	EXPECT_NE(ret, 0) {
+		TH_LOG("Managed to delete binder-control device");
+		goto umount;
+	}
+	EXPECT_EQ(errno, EPERM) {
+		TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
+			strerror(errno));
+		goto umount;
+	}
+
+	/* success: binder-control device removal failed as expected */
+
+	for (int i = 0; i < ARRAY_SIZE(binder_features); i++) {
+		snprintf(device_path, sizeof(device_path), "%s/features/%s",
+			 binderfs_mntpt, binder_features[i]);
+		fd = open(device_path, O_CLOEXEC | O_RDONLY);
+		EXPECT_GE(fd, 0) {
+			TH_LOG("%s - Failed to open binder feature: %s",
+				strerror(errno), binder_features[i]);
+			goto umount;
+		}
+		close(fd);
+	}
+
+	/* success: binder feature files found */
+	result = 0;
+
+umount:
+	ret = umount2(binderfs_mntpt, MNT_DETACH);
+	EXPECT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
+	}
+rmdir:
+	ret = rmdir(binderfs_mntpt);
+	EXPECT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
+	}
+out:
+	return result;
+}
+
+static int wait_for_pid(pid_t pid)
+{
+	int status, ret;
+
+again:
+	ret = waitpid(pid, &status, 0);
+	if (ret == -1) {
+		if (errno == EINTR)
+			goto again;
+
+		return -1;
+	}
+
+	if (!WIFEXITED(status))
+		return -1;
+
+	return WEXITSTATUS(status);
+}
+
+static int setid_userns_root(void)
+{
+	if (setuid(0))
+		return -1;
+	if (setgid(0))
+		return -1;
+
+	setfsuid(0);
+	setfsgid(0);
+
+	return 0;
+}
+
+enum idmap_type {
+	UID_MAP,
+	GID_MAP,
+};
+
+static ssize_t read_nointr(int fd, void *buf, size_t count)
+{
+	ssize_t ret;
+again:
+	ret = read(fd, buf, count);
+	if (ret < 0 && errno == EINTR)
+		goto again;
+
+	return ret;
+}
+
+static ssize_t write_nointr(int fd, const void *buf, size_t count)
+{
+	ssize_t ret;
+again:
+	ret = write(fd, buf, count);
+	if (ret < 0 && errno == EINTR)
+		goto again;
+
+	return ret;
+}
+
+static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
+			    size_t buf_size)
+{
+	int fd;
+	int ret;
+	char path[4096];
+
+	if (type == GID_MAP) {
+		int setgroups_fd;
+
+		snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
+		setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
+		if (setgroups_fd < 0 && errno != ENOENT)
+			return -1;
+
+		if (setgroups_fd >= 0) {
+			ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
+			close_prot_errno_disarm(setgroups_fd);
+			if (ret != sizeof("deny") - 1)
+				return -1;
+		}
+	}
+
+	switch (type) {
+	case UID_MAP:
+		ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
+		break;
+	case GID_MAP:
+		ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
+		break;
+	default:
+		return -1;
+	}
+	if (ret < 0 || ret >= sizeof(path))
+		return -E2BIG;
+
+	fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
+	if (fd < 0)
+		return -1;
+
+	ret = write_nointr(fd, buf, buf_size);
+	close_prot_errno_disarm(fd);
+	if (ret != buf_size)
+		return -1;
+
+	return 0;
+}
+
+static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
+{
+	int ret;
+	char buf;
+
+	close_prot_errno_disarm(syncfds[1]);
+
+	ret = unshare(CLONE_NEWUSER);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to unshare user namespace",
+			strerror(errno));
+	}
+
+	ret = write_nointr(syncfds[0], "1", 1);
+	ASSERT_EQ(ret, 1) {
+		TH_LOG("write_nointr() failed");
+	}
+
+	ret = read_nointr(syncfds[0], &buf, 1);
+	ASSERT_EQ(ret, 1) {
+		TH_LOG("read_nointr() failed");
+	}
+
+	close_prot_errno_disarm(syncfds[0]);
+
+	ASSERT_EQ(setid_userns_root(), 0) {
+		TH_LOG("setid_userns_root() failed");
+	}
+}
+
+static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
+{
+	int ret;
+	char buf;
+	char id_map[4096];
+
+	close_prot_errno_disarm(syncfds[0]);
+
+	ret = read_nointr(syncfds[1], &buf, 1);
+	ASSERT_EQ(ret, 1) {
+		TH_LOG("read_nointr() failed");
+	}
+
+	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
+	ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("write_id_mapping(UID_MAP) failed");
+	}
+
+	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
+	ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("write_id_mapping(GID_MAP) failed");
+	}
+
+	ret = write_nointr(syncfds[1], "1", 1);
+	ASSERT_EQ(ret, 1) {
+		TH_LOG("write_nointr() failed");
+	}
+
+	close_prot_errno_disarm(syncfds[1]);
+}
+
+struct __test_metadata *_thread_metadata;
+static void *binder_version_thread(void *data)
+{
+	struct __test_metadata *_metadata = _thread_metadata;
+	int fd = PTR_TO_INT(data);
+	struct binder_version version = { 0 };
+	int ret;
+
+	ret = ioctl(fd, BINDER_VERSION, &version);
+	if (ret < 0)
+		TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
+			strerror(errno));
+
+	pthread_exit(data);
+}
+
+/*
+ * Regression test:
+ * 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
+ * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
+ * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
+ */
+TEST(binderfs_stress)
+{
+	int fds[1000];
+	int syncfds[2];
+	pid_t pid;
+	int fd, ret;
+	size_t len;
+	struct binderfs_device device = { 0 };
+	char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
+		device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
+
+	ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to create socket pair", strerror(errno));
+	}
+
+	pid = fork();
+	ASSERT_GE(pid, 0) {
+		TH_LOG("%s - Failed to fork", strerror(errno));
+		close_prot_errno_disarm(syncfds[0]);
+		close_prot_errno_disarm(syncfds[1]);
+	}
+
+	if (pid == 0) {
+		int i, j, k, nthreads;
+		pthread_attr_t attr;
+		pthread_t threads[DEFAULT_THREADS];
+		change_userns(_metadata, syncfds);
+		change_mountns(_metadata);
+
+		ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
+			TH_LOG("%s - Failed to create binderfs mountpoint",
+				strerror(errno));
+		}
+
+		ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
+		ASSERT_EQ(ret, 0) {
+			TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel",
+				strerror(errno));
+		}
+
+		for (int i = 0; i < ARRAY_SIZE(fds); i++) {
+
+			snprintf(device_path, sizeof(device_path),
+				 "%s/binder-control", binderfs_mntpt);
+			fd = open(device_path, O_RDONLY | O_CLOEXEC);
+			ASSERT_GE(fd, 0) {
+				TH_LOG("%s - Failed to open binder-control device",
+					strerror(errno));
+			}
+
+			memset(&device, 0, sizeof(device));
+			snprintf(device.name, sizeof(device.name), "%d", i);
+			ret = ioctl(fd, BINDER_CTL_ADD, &device);
+			close_prot_errno_disarm(fd);
+			ASSERT_EQ(ret, 0) {
+				TH_LOG("%s - Failed to allocate new binder device",
+					strerror(errno));
+			}
+
+			snprintf(device_path, sizeof(device_path), "%s/%d",
+				 binderfs_mntpt, i);
+			fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
+			ASSERT_GE(fds[i], 0) {
+				TH_LOG("%s - Failed to open binder device", strerror(errno));
+			}
+		}
+
+		ret = umount2(binderfs_mntpt, MNT_DETACH);
+		ASSERT_EQ(ret, 0) {
+			TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
+			rmdir(binderfs_mntpt);
+		}
+
+		nthreads = get_nprocs_conf();
+		if (nthreads > DEFAULT_THREADS)
+			nthreads = DEFAULT_THREADS;
+
+		_thread_metadata = _metadata;
+		pthread_attr_init(&attr);
+		for (k = 0; k < ARRAY_SIZE(fds); k++) {
+			for (i = 0; i < nthreads; i++) {
+				ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
+				if (ret) {
+					TH_LOG("%s - Failed to create thread %d",
+						strerror(errno), i);
+					break;
+				}
+			}
+
+			for (j = 0; j < i; j++) {
+				void *fdptr = NULL;
+
+				ret = pthread_join(threads[j], &fdptr);
+				if (ret)
+					TH_LOG("%s - Failed to join thread %d for fd %d",
+						strerror(errno), j, PTR_TO_INT(fdptr));
+			}
+		}
+		pthread_attr_destroy(&attr);
+
+		for (k = 0; k < ARRAY_SIZE(fds); k++)
+			close(fds[k]);
+
+		exit(EXIT_SUCCESS);
+	}
+
+	change_idmaps(_metadata, syncfds, pid);
+
+	ret = wait_for_pid(pid);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("wait_for_pid() failed");
+	}
+}
+
+TEST(binderfs_test_privileged)
+{
+	if (geteuid() != 0)
+		SKIP(return, "Tests are not run as root. Skipping privileged tests");
+
+	if (__do_binderfs_test(_metadata))
+		SKIP(return, "The Android binderfs filesystem is not available");
+}
+
+TEST(binderfs_test_unprivileged)
+{
+	int ret;
+	int syncfds[2];
+	pid_t pid;
+
+	ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("%s - Failed to create socket pair", strerror(errno));
+	}
+
+	pid = fork();
+	ASSERT_GE(pid, 0) {
+		close_prot_errno_disarm(syncfds[0]);
+		close_prot_errno_disarm(syncfds[1]);
+		TH_LOG("%s - Failed to fork", strerror(errno));
+	}
+
+	if (pid == 0) {
+		change_userns(_metadata, syncfds);
+		if (__do_binderfs_test(_metadata))
+			exit(2);
+		exit(EXIT_SUCCESS);
+	}
+
+	change_idmaps(_metadata, syncfds, pid);
+
+	ret = wait_for_pid(pid);
+	if (ret) {
+		if (ret == 2)
+			SKIP(return, "The Android binderfs filesystem is not available");
+		ASSERT_EQ(ret, 0) {
+			TH_LOG("wait_for_pid() failed");
+		}
+	}
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/filesystems/binderfs/config b/tools/testing/selftests/filesystems/binderfs/config
new file mode 100644
index 000000000..7b4fc6ee6
--- /dev/null
+++ b/tools/testing/selftests/filesystems/binderfs/config
@@ -0,0 +1,2 @@
+CONFIG_ANDROID_BINDERFS=y
+CONFIG_ANDROID_BINDER_IPC=y
diff --git a/tools/testing/selftests/filesystems/devpts_pts.c b/tools/testing/selftests/filesystems/devpts_pts.c
new file mode 100644
index 000000000..b1fc9b916
--- /dev/null
+++ b/tools/testing/selftests/filesystems/devpts_pts.c
@@ -0,0 +1,316 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <asm/ioctls.h>
+#include <sys/mount.h>
+#include <sys/wait.h>
+#include "../kselftest.h"
+
+static bool terminal_dup2(int duplicate, int original)
+{
+	int ret;
+
+	ret = dup2(duplicate, original);
+	if (ret < 0)
+		return false;
+
+	return true;
+}
+
+static int terminal_set_stdfds(int fd)
+{
+	int i;
+
+	if (fd < 0)
+		return 0;
+
+	for (i = 0; i < 3; i++)
+		if (!terminal_dup2(fd, (int[]){STDIN_FILENO, STDOUT_FILENO,
+					       STDERR_FILENO}[i]))
+			return -1;
+
+	return 0;
+}
+
+static int login_pty(int fd)
+{
+	int ret;
+
+	setsid();
+
+	ret = ioctl(fd, TIOCSCTTY, NULL);
+	if (ret < 0)
+		return -1;
+
+	ret = terminal_set_stdfds(fd);
+	if (ret < 0)
+		return -1;
+
+	if (fd > STDERR_FILENO)
+		close(fd);
+
+	return 0;
+}
+
+static int wait_for_pid(pid_t pid)
+{
+	int status, ret;
+
+again:
+	ret = waitpid(pid, &status, 0);
+	if (ret == -1) {
+		if (errno == EINTR)
+			goto again;
+		return -1;
+	}
+	if (ret != pid)
+		goto again;
+
+	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+		return -1;
+
+	return 0;
+}
+
+static int resolve_procfd_symlink(int fd, char *buf, size_t buflen)
+{
+	int ret;
+	char procfd[4096];
+
+	ret = snprintf(procfd, 4096, "/proc/self/fd/%d", fd);
+	if (ret < 0 || ret >= 4096)
+		return -1;
+
+	ret = readlink(procfd, buf, buflen);
+	if (ret < 0 || (size_t)ret >= buflen)
+		return -1;
+
+	buf[ret] = '\0';
+
+	return 0;
+}
+
+static int do_tiocgptpeer(char *ptmx, char *expected_procfd_contents)
+{
+	int ret;
+	int master = -1, slave = -1, fret = -1;
+
+	master = open(ptmx, O_RDWR | O_NOCTTY | O_CLOEXEC);
+	if (master < 0) {
+		fprintf(stderr, "Failed to open \"%s\": %s\n", ptmx,
+			strerror(errno));
+		return -1;
+	}
+
+	/*
+	 * grantpt() makes assumptions about /dev/pts/ so ignore it. It's also
+	 * not really needed.
+	 */
+	ret = unlockpt(master);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to unlock terminal\n");
+		goto do_cleanup;
+	}
+
+#ifdef TIOCGPTPEER
+	slave = ioctl(master, TIOCGPTPEER, O_RDWR | O_NOCTTY | O_CLOEXEC);
+#endif
+	if (slave < 0) {
+		if (errno == EINVAL) {
+			fprintf(stderr, "TIOCGPTPEER is not supported. "
+					"Skipping test.\n");
+			fret = KSFT_SKIP;
+		} else {
+			fprintf(stderr,
+				"Failed to perform TIOCGPTPEER ioctl\n");
+			fret = EXIT_FAILURE;
+		}
+		goto do_cleanup;
+	}
+
+	pid_t pid = fork();
+	if (pid < 0)
+		goto do_cleanup;
+
+	if (pid == 0) {
+		char buf[4096];
+
+		ret = login_pty(slave);
+		if (ret < 0) {
+			fprintf(stderr, "Failed to setup terminal\n");
+			_exit(EXIT_FAILURE);
+		}
+
+		ret = resolve_procfd_symlink(STDIN_FILENO, buf, sizeof(buf));
+		if (ret < 0) {
+			fprintf(stderr, "Failed to retrieve pathname of pts "
+					"slave file descriptor\n");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (strncmp(expected_procfd_contents, buf,
+			    strlen(expected_procfd_contents)) != 0) {
+			fprintf(stderr, "Received invalid contents for "
+					"\"/proc/<pid>/fd/%d\" symlink: %s\n",
+					STDIN_FILENO, buf);
+			_exit(-1);
+		}
+
+		fprintf(stderr, "Contents of \"/proc/<pid>/fd/%d\" "
+				"symlink are valid: %s\n", STDIN_FILENO, buf);
+
+		_exit(EXIT_SUCCESS);
+	}
+
+	ret = wait_for_pid(pid);
+	if (ret < 0)
+		goto do_cleanup;
+
+	fret = EXIT_SUCCESS;
+
+do_cleanup:
+	if (master >= 0)
+		close(master);
+	if (slave >= 0)
+		close(slave);
+
+	return fret;
+}
+
+static int verify_non_standard_devpts_mount(void)
+{
+	char *mntpoint;
+	int ret = -1;
+	char devpts[] = P_tmpdir "/devpts_fs_XXXXXX";
+	char ptmx[] = P_tmpdir "/devpts_fs_XXXXXX/ptmx";
+
+	ret = umount("/dev/pts");
+	if (ret < 0) {
+		fprintf(stderr, "Failed to unmount \"/dev/pts\": %s\n",
+				strerror(errno));
+		return -1;
+	}
+
+	(void)umount("/dev/ptmx");
+
+	mntpoint = mkdtemp(devpts);
+	if (!mntpoint) {
+		fprintf(stderr, "Failed to create temporary mountpoint: %s\n",
+				 strerror(errno));
+		return -1;
+	}
+
+	ret = mount("devpts", mntpoint, "devpts", MS_NOSUID | MS_NOEXEC,
+		    "newinstance,ptmxmode=0666,mode=0620,gid=5");
+	if (ret < 0) {
+		fprintf(stderr, "Failed to mount devpts fs to \"%s\" in new "
+				"mount namespace: %s\n", mntpoint,
+				strerror(errno));
+		unlink(mntpoint);
+		return -1;
+	}
+
+	ret = snprintf(ptmx, sizeof(ptmx), "%s/ptmx", devpts);
+	if (ret < 0 || (size_t)ret >= sizeof(ptmx)) {
+		unlink(mntpoint);
+		return -1;
+	}
+
+	ret = do_tiocgptpeer(ptmx, mntpoint);
+	unlink(mntpoint);
+	if (ret < 0)
+		return -1;
+
+	return 0;
+}
+
+static int verify_ptmx_bind_mount(void)
+{
+	int ret;
+
+	ret = mount("/dev/pts/ptmx", "/dev/ptmx", NULL, MS_BIND, NULL);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
+				"\"/dev/ptmx\" mount namespace\n");
+		return -1;
+	}
+
+	ret = do_tiocgptpeer("/dev/ptmx", "/dev/pts/");
+	if (ret < 0)
+		return -1;
+
+	return 0;
+}
+
+static int verify_invalid_ptmx_bind_mount(void)
+{
+	int ret;
+	char mntpoint_fd;
+	char ptmx[] = P_tmpdir "/devpts_ptmx_XXXXXX";
+
+	mntpoint_fd = mkstemp(ptmx);
+	if (mntpoint_fd < 0) {
+		fprintf(stderr, "Failed to create temporary directory: %s\n",
+				 strerror(errno));
+		return -1;
+	}
+
+	ret = mount("/dev/pts/ptmx", ptmx, NULL, MS_BIND, NULL);
+	close(mntpoint_fd);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
+				"\"%s\" mount namespace\n", ptmx);
+		return -1;
+	}
+
+	ret = do_tiocgptpeer(ptmx, "/dev/pts/");
+	if (ret == 0)
+		return -1;
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	if (!isatty(STDIN_FILENO)) {
+		fprintf(stderr, "Standard input file descriptor is not attached "
+				"to a terminal. Skipping test\n");
+		exit(KSFT_SKIP);
+	}
+
+	ret = unshare(CLONE_NEWNS);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to unshare mount namespace\n");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to make \"/\" MS_PRIVATE in new mount "
+				"namespace\n");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = verify_ptmx_bind_mount();
+	if (ret < 0)
+		exit(EXIT_FAILURE);
+
+	ret = verify_invalid_ptmx_bind_mount();
+	if (ret < 0)
+		exit(EXIT_FAILURE);
+
+	ret = verify_non_standard_devpts_mount();
+	if (ret < 0)
+		exit(EXIT_FAILURE);
+
+	exit(EXIT_SUCCESS);
+}
diff --git a/tools/testing/selftests/filesystems/dnotify_test.c b/tools/testing/selftests/filesystems/dnotify_test.c
new file mode 100644
index 000000000..c0a9b2d33
--- /dev/null
+++ b/tools/testing/selftests/filesystems/dnotify_test.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE	/* needed to get the defines */
+#include <fcntl.h>	/* in glibc 2.2 this has the needed
+				   values defined */
+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static volatile int event_fd;
+
+static void handler(int sig, siginfo_t *si, void *data)
+{
+	event_fd = si->si_fd;
+}
+
+int main(void)
+{
+	struct sigaction act;
+	int fd;
+
+	act.sa_sigaction = handler;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = SA_SIGINFO;
+	sigaction(SIGRTMIN + 1, &act, NULL);
+
+	fd = open(".", O_RDONLY);
+	fcntl(fd, F_SETSIG, SIGRTMIN + 1);
+	fcntl(fd, F_NOTIFY, DN_MODIFY|DN_CREATE|DN_MULTISHOT);
+	/* we will now be notified if any of the files
+	   in "." is modified or new files are created */
+	while (1) {
+		pause();
+		printf("Got event on fd=%d\n", event_fd);
+	}
+}
diff --git a/tools/testing/selftests/filesystems/epoll/.gitignore b/tools/testing/selftests/filesystems/epoll/.gitignore
new file mode 100644
index 000000000..909015725
--- /dev/null
+++ b/tools/testing/selftests/filesystems/epoll/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+epoll_wakeup_test
diff --git a/tools/testing/selftests/filesystems/epoll/Makefile b/tools/testing/selftests/filesystems/epoll/Makefile
new file mode 100644
index 000000000..0788a7dc8
--- /dev/null
+++ b/tools/testing/selftests/filesystems/epoll/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += $(KHDR_INCLUDES)
+LDLIBS += -lpthread
+TEST_GEN_PROGS := epoll_wakeup_test
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
new file mode 100644
index 000000000..65ede5063
--- /dev/null
+++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
@@ -0,0 +1,3496 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <asm/unistd.h>
+#include <linux/time_types.h>
+#include <poll.h>
+#include <unistd.h>
+#include <assert.h>
+#include <signal.h>
+#include <pthread.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
+#include <sys/eventfd.h>
+#include "../../kselftest_harness.h"
+
+struct epoll_mtcontext
+{
+	int efd[3];
+	int sfd[4];
+	volatile int count;
+
+	pthread_t main;
+	pthread_t waiter;
+};
+
+#ifndef __NR_epoll_pwait2
+#define __NR_epoll_pwait2 -1
+#endif
+
+static inline int sys_epoll_pwait2(int fd, struct epoll_event *events,
+				   int maxevents,
+				   const struct __kernel_timespec *timeout,
+				   const sigset_t *sigset, size_t sigsetsize)
+{
+	return syscall(__NR_epoll_pwait2, fd, events, maxevents, timeout,
+		       sigset, sigsetsize);
+}
+
+static void signal_handler(int signum)
+{
+}
+
+static void kill_timeout(struct epoll_mtcontext *ctx)
+{
+	usleep(1000000);
+	pthread_kill(ctx->main, SIGUSR1);
+	pthread_kill(ctx->waiter, SIGUSR1);
+}
+
+static void *waiter_entry1a(void *data)
+{
+	struct epoll_event e;
+	struct epoll_mtcontext *ctx = data;
+
+	if (epoll_wait(ctx->efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx->count, 1);
+
+	return NULL;
+}
+
+static void *waiter_entry1ap(void *data)
+{
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext *ctx = data;
+
+	pfd.fd = ctx->efd[0];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx->efd[0], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx->count, 1);
+	}
+
+	return NULL;
+}
+
+static void *waiter_entry1o(void *data)
+{
+	struct epoll_event e;
+	struct epoll_mtcontext *ctx = data;
+
+	if (epoll_wait(ctx->efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx->count, 1);
+
+	return NULL;
+}
+
+static void *waiter_entry1op(void *data)
+{
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext *ctx = data;
+
+	pfd.fd = ctx->efd[0];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx->efd[0], &e, 1, 0) > 0)
+			__sync_fetch_and_or(&ctx->count, 1);
+	}
+
+	return NULL;
+}
+
+static void *waiter_entry2a(void *data)
+{
+	struct epoll_event events[2];
+	struct epoll_mtcontext *ctx = data;
+
+	if (epoll_wait(ctx->efd[0], events, 2, -1) > 0)
+		__sync_fetch_and_add(&ctx->count, 1);
+
+	return NULL;
+}
+
+static void *waiter_entry2ap(void *data)
+{
+	struct pollfd pfd;
+	struct epoll_event events[2];
+	struct epoll_mtcontext *ctx = data;
+
+	pfd.fd = ctx->efd[0];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx->efd[0], events, 2, 0) > 0)
+			__sync_fetch_and_add(&ctx->count, 1);
+	}
+
+	return NULL;
+}
+
+static void *emitter_entry1(void *data)
+{
+	struct epoll_mtcontext *ctx = data;
+
+	usleep(100000);
+	write(ctx->sfd[1], "w", 1);
+
+	kill_timeout(ctx);
+
+	return NULL;
+}
+
+static void *emitter_entry2(void *data)
+{
+	struct epoll_mtcontext *ctx = data;
+
+	usleep(100000);
+	write(ctx->sfd[1], "w", 1);
+	write(ctx->sfd[3], "w", 1);
+
+	kill_timeout(ctx);
+
+	return NULL;
+}
+
+/*
+ *          t0
+ *           | (ew)
+ *          e0
+ *           | (lt)
+ *          s0
+ */
+TEST(epoll1)
+{
+	int efd;
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (ew)
+ *          e0
+ *           | (et)
+ *          s0
+ */
+TEST(epoll2)
+{
+	int efd;
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd, &e, 1, 0), 0);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        s0    s2
+ */
+TEST(epoll3)
+{
+	int efd;
+	int sfd[4];
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *     (et) /  \ (et)
+ *        s0    s2
+ */
+TEST(epoll4)
+{
+	int efd;
+	int sfd[4];
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 0);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (lt)
+ *          s0
+ */
+TEST(epoll5)
+{
+	int efd;
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	ASSERT_EQ(poll(&pfd, 1, 0), 1);
+	ASSERT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	ASSERT_EQ(poll(&pfd, 1, 0), 1);
+	ASSERT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (et)
+ *          s0
+ */
+TEST(epoll6)
+{
+	int efd;
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	ASSERT_EQ(poll(&pfd, 1, 0), 1);
+	ASSERT_EQ(epoll_wait(efd, &e, 1, 0), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	ASSERT_EQ(poll(&pfd, 1, 0), 0);
+	ASSERT_EQ(epoll_wait(efd, &e, 1, 0), 0);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *           t0
+ *            | (p)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        s0    s2
+ */
+
+TEST(epoll7)
+{
+	int efd;
+	int sfd[4];
+	struct pollfd pfd;
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *           t0
+ *            | (p)
+ *           e0
+ *     (et) /  \ (et)
+ *        s0    s2
+ */
+TEST(epoll8)
+{
+	int efd;
+	int sfd[4];
+	struct pollfd pfd;
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 2);
+
+	pfd.fd = efd;
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 0);
+	EXPECT_EQ(epoll_wait(efd, events, 2, 0), 0);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll9)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (et)
+ *           s0
+ */
+TEST(epoll10)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        s0    s2
+ */
+TEST(epoll11)
+{
+	pthread_t emitter;
+	struct epoll_event events[2];
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[2], events), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry2a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], events, 2, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *     (et) /  \ (et)
+ *        s0    s2
+ */
+TEST(epoll12)
+{
+	pthread_t emitter;
+	struct epoll_event events[2];
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[2], events), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], events, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll13)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (et)
+ *           s0
+ */
+TEST(epoll14)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        s0    s2
+ */
+TEST(epoll15)
+{
+	pthread_t emitter;
+	struct epoll_event events[2];
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[2], events), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry2ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], events, 2, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *     (et) /  \ (et)
+ *        s0    s2
+ */
+TEST(epoll16)
+{
+	pthread_t emitter;
+	struct epoll_event events[2];
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[2], events), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], events, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *          t0
+ *           | (ew)
+ *          e0
+ *           | (lt)
+ *          e1
+ *           | (lt)
+ *          s0
+ */
+TEST(epoll17)
+{
+	int efd[2];
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (ew)
+ *          e0
+ *           | (lt)
+ *          e1
+ *           | (et)
+ *          s0
+ */
+TEST(epoll18)
+{
+	int efd[2];
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll19)
+{
+	int efd[2];
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll20)
+{
+	int efd[2];
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (lt)
+ *          e1
+ *           | (lt)
+ *          s0
+ */
+TEST(epoll21)
+{
+	int efd[2];
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (lt)
+ *          e1
+ *           | (et)
+ *          s0
+ */
+TEST(epoll22)
+{
+	int efd[2];
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (et)
+ *          e1
+ *           | (lt)
+ *          s0
+ */
+TEST(epoll23)
+{
+	int efd[2];
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 0);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *          t0
+ *           | (p)
+ *          e0
+ *           | (et)
+ *          e1
+ *           | (et)
+ *          s0
+ */
+TEST(epoll24)
+{
+	int efd[2];
+	int sfd[2];
+	struct pollfd pfd;
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 0);
+	EXPECT_EQ(epoll_wait(efd[0], &e, 1, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll25)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll26)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll27)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll28)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll29)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll30)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll31)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *            | (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll32)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 1);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (ew)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll33)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (ew)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll34)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1o, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (ew)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll35)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (ew)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll36)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1o, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (ew)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll37)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (ew)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll38)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1o, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_or(&ctx.count, 2);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (ew)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll39)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (ew)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll40)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1o, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_or(&ctx.count, 2);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (p)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll41)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (p)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll42)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1op, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (p)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll43)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *    (ew) |    | (p)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll44)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1op, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (p)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll45)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (p)
+ *         |   e0
+ *          \  / (lt)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll46)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1op, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (p)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll47)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	pfd.fd = ctx.efd[1];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[1], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *        t0   t1
+ *     (p) |    | (p)
+ *         |   e0
+ *          \  / (et)
+ *           e1
+ *            | (et)
+ *           s0
+ */
+TEST(epoll48)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1op, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry1, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[1], &e, 1, -1) > 0)
+		__sync_fetch_and_or(&ctx.count, 2);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_TRUE((ctx.count == 2) || (ctx.count == 3));
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll49)
+{
+	int efd[3];
+	int sfd[4];
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	efd[2] = epoll_create(1);
+	ASSERT_GE(efd[2], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[2], EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(efd[2]);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *           t0
+ *            | (ew)
+ *           e0
+ *     (et) /  \ (et)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll50)
+{
+	int efd[3];
+	int sfd[4];
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	efd[2] = epoll_create(1);
+	ASSERT_GE(efd[2], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[2], EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(efd[2]);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *           t0
+ *            | (p)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll51)
+{
+	int efd[3];
+	int sfd[4];
+	struct pollfd pfd;
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	efd[2] = epoll_create(1);
+	ASSERT_GE(efd[2], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[2], EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(efd[2]);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *           t0
+ *            | (p)
+ *           e0
+ *     (et) /  \ (et)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll52)
+{
+	int efd[3];
+	int sfd[4];
+	struct pollfd pfd;
+	struct epoll_event events[2];
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &sfd[2]), 0);
+
+	efd[0] = epoll_create(1);
+	ASSERT_GE(efd[0], 0);
+
+	efd[1] = epoll_create(1);
+	ASSERT_GE(efd[1], 0);
+
+	efd[2] = epoll_create(1);
+	ASSERT_GE(efd[2], 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[1], EPOLL_CTL_ADD, sfd[0], events), 0);
+
+	events[0].events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd[2], EPOLL_CTL_ADD, sfd[2], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[1], events), 0);
+
+	events[0].events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd[0], EPOLL_CTL_ADD, efd[2], events), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+	ASSERT_EQ(write(sfd[3], "w", 1), 1);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 1);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 2);
+
+	pfd.fd = efd[0];
+	pfd.events = POLLIN;
+	EXPECT_EQ(poll(&pfd, 1, 0), 0);
+	EXPECT_EQ(epoll_wait(efd[0], events, 2, 0), 0);
+
+	close(efd[0]);
+	close(efd[1]);
+	close(efd[2]);
+	close(sfd[0]);
+	close(sfd[1]);
+	close(sfd[2]);
+	close(sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll53)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *     (et) /  \ (et)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll54)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll55)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (p)
+ *           e0
+ *     (et) /  \ (et)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll56)
+{
+	pthread_t emitter;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	if (epoll_wait(ctx.efd[0], &e, 1, -1) > 0)
+		__sync_fetch_and_add(&ctx.count, 1);
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *      (p) \  / (p)
+ *           e0
+ *     (lt) /  \ (lt)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll57)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	pfd.fd = ctx.efd[0];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[0], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+/*
+ *        t0    t1
+ *      (p) \  / (p)
+ *           e0
+ *     (et) /  \ (et)
+ *        e1    e2
+ *    (lt) |     | (lt)
+ *        s0    s2
+ */
+TEST(epoll58)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[0]), 0);
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, &ctx.sfd[2]), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.efd[1] = epoll_create(1);
+	ASSERT_GE(ctx.efd[1], 0);
+
+	ctx.efd[2] = epoll_create(1);
+	ASSERT_GE(ctx.efd[2], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[1], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[2], EPOLL_CTL_ADD, ctx.sfd[2], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[1], &e), 0);
+
+	e.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.efd[2], &e), 0);
+
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&ctx.waiter, NULL, waiter_entry1ap, &ctx), 0);
+	ASSERT_EQ(pthread_create(&emitter, NULL, emitter_entry2, &ctx), 0);
+
+	pfd.fd = ctx.efd[0];
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, -1) > 0) {
+		if (epoll_wait(ctx.efd[0], &e, 1, 0) > 0)
+			__sync_fetch_and_add(&ctx.count, 1);
+	}
+
+	ASSERT_EQ(pthread_join(ctx.waiter, NULL), 0);
+	EXPECT_EQ(ctx.count, 2);
+
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+
+	close(ctx.efd[0]);
+	close(ctx.efd[1]);
+	close(ctx.efd[2]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+	close(ctx.sfd[2]);
+	close(ctx.sfd[3]);
+}
+
+static void *epoll59_thread(void *ctx_)
+{
+	struct epoll_mtcontext *ctx = ctx_;
+	struct epoll_event e;
+	int i;
+
+	for (i = 0; i < 100000; i++) {
+		while (ctx->count == 0)
+			;
+
+		e.events = EPOLLIN | EPOLLERR | EPOLLET;
+		epoll_ctl(ctx->efd[0], EPOLL_CTL_MOD, ctx->sfd[0], &e);
+		ctx->count = 0;
+	}
+
+	return NULL;
+}
+
+/*
+ *        t0
+ *      (p) \
+ *           e0
+ *     (et) /
+ *        e0
+ *
+ * Based on https://bugzilla.kernel.org/show_bug.cgi?id=205933
+ */
+TEST(epoll59)
+{
+	pthread_t emitter;
+	struct pollfd pfd;
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+	int i, ret;
+
+	signal(SIGUSR1, signal_handler);
+
+	ctx.efd[0] = epoll_create1(0);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	ctx.sfd[0] = eventfd(1, 0);
+	ASSERT_GE(ctx.sfd[0], 0);
+
+	e.events = EPOLLIN | EPOLLERR | EPOLLET;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	ASSERT_EQ(pthread_create(&emitter, NULL, epoll59_thread, &ctx), 0);
+
+	for (i = 0; i < 100000; i++) {
+		ret = epoll_wait(ctx.efd[0], &e, 1, 1000);
+		ASSERT_GT(ret, 0);
+
+		while (ctx.count != 0)
+			;
+		ctx.count = 1;
+	}
+	if (pthread_tryjoin_np(emitter, NULL) < 0) {
+		pthread_kill(emitter, SIGUSR1);
+		pthread_join(emitter, NULL);
+	}
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+}
+
+enum {
+	EPOLL60_EVENTS_NR = 10,
+};
+
+struct epoll60_ctx {
+	volatile int stopped;
+	int ready;
+	int waiters;
+	int epfd;
+	int evfd[EPOLL60_EVENTS_NR];
+};
+
+static void *epoll60_wait_thread(void *ctx_)
+{
+	struct epoll60_ctx *ctx = ctx_;
+	struct epoll_event e;
+	sigset_t sigmask;
+	uint64_t v;
+	int ret;
+
+	/* Block SIGUSR1 */
+	sigemptyset(&sigmask);
+	sigaddset(&sigmask, SIGUSR1);
+	sigprocmask(SIG_SETMASK, &sigmask, NULL);
+
+	/* Prepare empty mask for epoll_pwait() */
+	sigemptyset(&sigmask);
+
+	while (!ctx->stopped) {
+		/* Mark we are ready */
+		__atomic_fetch_add(&ctx->ready, 1, __ATOMIC_ACQUIRE);
+
+		/* Start when all are ready */
+		while (__atomic_load_n(&ctx->ready, __ATOMIC_ACQUIRE) &&
+		       !ctx->stopped);
+
+		/* Account this waiter */
+		__atomic_fetch_add(&ctx->waiters, 1, __ATOMIC_ACQUIRE);
+
+		ret = epoll_pwait(ctx->epfd, &e, 1, 2000, &sigmask);
+		if (ret != 1) {
+			/* We expect only signal delivery on stop */
+			assert(ret < 0 && errno == EINTR && "Lost wakeup!\n");
+			assert(ctx->stopped);
+			break;
+		}
+
+		ret = read(e.data.fd, &v, sizeof(v));
+		/* Since we are on ET mode, thus each thread gets its own fd. */
+		assert(ret == sizeof(v));
+
+		__atomic_fetch_sub(&ctx->waiters, 1, __ATOMIC_RELEASE);
+	}
+
+	return NULL;
+}
+
+static inline unsigned long long msecs(void)
+{
+	struct timespec ts;
+	unsigned long long msecs;
+
+	clock_gettime(CLOCK_REALTIME, &ts);
+	msecs = ts.tv_sec * 1000ull;
+	msecs += ts.tv_nsec / 1000000ull;
+
+	return msecs;
+}
+
+static inline int count_waiters(struct epoll60_ctx *ctx)
+{
+	return __atomic_load_n(&ctx->waiters, __ATOMIC_ACQUIRE);
+}
+
+TEST(epoll60)
+{
+	struct epoll60_ctx ctx = { 0 };
+	pthread_t waiters[ARRAY_SIZE(ctx.evfd)];
+	struct epoll_event e;
+	int i, n, ret;
+
+	signal(SIGUSR1, signal_handler);
+
+	ctx.epfd = epoll_create1(0);
+	ASSERT_GE(ctx.epfd, 0);
+
+	/* Create event fds */
+	for (i = 0; i < ARRAY_SIZE(ctx.evfd); i++) {
+		ctx.evfd[i] = eventfd(0, EFD_NONBLOCK);
+		ASSERT_GE(ctx.evfd[i], 0);
+
+		e.events = EPOLLIN | EPOLLET;
+		e.data.fd = ctx.evfd[i];
+		ASSERT_EQ(epoll_ctl(ctx.epfd, EPOLL_CTL_ADD, ctx.evfd[i], &e), 0);
+	}
+
+	/* Create waiter threads */
+	for (i = 0; i < ARRAY_SIZE(waiters); i++)
+		ASSERT_EQ(pthread_create(&waiters[i], NULL,
+					 epoll60_wait_thread, &ctx), 0);
+
+	for (i = 0; i < 300; i++) {
+		uint64_t v = 1, ms;
+
+		/* Wait for all to be ready */
+		while (__atomic_load_n(&ctx.ready, __ATOMIC_ACQUIRE) !=
+		       ARRAY_SIZE(ctx.evfd))
+			;
+
+		/* Steady, go */
+		__atomic_fetch_sub(&ctx.ready, ARRAY_SIZE(ctx.evfd),
+				   __ATOMIC_ACQUIRE);
+
+		/* Wait all have gone to kernel */
+		while (count_waiters(&ctx) != ARRAY_SIZE(ctx.evfd))
+			;
+
+		/* 1ms should be enough to schedule away */
+		usleep(1000);
+
+		/* Quickly signal all handles at once */
+		for (n = 0; n < ARRAY_SIZE(ctx.evfd); n++) {
+			ret = write(ctx.evfd[n], &v, sizeof(v));
+			ASSERT_EQ(ret, sizeof(v));
+		}
+
+		/* Busy loop for 1s and wait for all waiters to wake up */
+		ms = msecs();
+		while (count_waiters(&ctx) && msecs() < ms + 1000)
+			;
+
+		ASSERT_EQ(count_waiters(&ctx), 0);
+	}
+	ctx.stopped = 1;
+	/* Stop waiters */
+	for (i = 0; i < ARRAY_SIZE(waiters); i++)
+		ret = pthread_kill(waiters[i], SIGUSR1);
+	for (i = 0; i < ARRAY_SIZE(waiters); i++)
+		pthread_join(waiters[i], NULL);
+
+	for (i = 0; i < ARRAY_SIZE(waiters); i++)
+		close(ctx.evfd[i]);
+	close(ctx.epfd);
+}
+
+struct epoll61_ctx {
+	int epfd;
+	int evfd;
+};
+
+static void *epoll61_write_eventfd(void *ctx_)
+{
+	struct epoll61_ctx *ctx = ctx_;
+	int64_t l = 1;
+
+	usleep(10950);
+	write(ctx->evfd, &l, sizeof(l));
+	return NULL;
+}
+
+static void *epoll61_epoll_with_timeout(void *ctx_)
+{
+	struct epoll61_ctx *ctx = ctx_;
+	struct epoll_event events[1];
+	int n;
+
+	n = epoll_wait(ctx->epfd, events, 1, 11);
+	/*
+	 * If epoll returned the eventfd, write on the eventfd to wake up the
+	 * blocking poller.
+	 */
+	if (n == 1) {
+		int64_t l = 1;
+
+		write(ctx->evfd, &l, sizeof(l));
+	}
+	return NULL;
+}
+
+static void *epoll61_blocking_epoll(void *ctx_)
+{
+	struct epoll61_ctx *ctx = ctx_;
+	struct epoll_event events[1];
+
+	epoll_wait(ctx->epfd, events, 1, -1);
+	return NULL;
+}
+
+TEST(epoll61)
+{
+	struct epoll61_ctx ctx;
+	struct epoll_event ev;
+	int i, r;
+
+	ctx.epfd = epoll_create1(0);
+	ASSERT_GE(ctx.epfd, 0);
+	ctx.evfd = eventfd(0, EFD_NONBLOCK);
+	ASSERT_GE(ctx.evfd, 0);
+
+	ev.events = EPOLLIN | EPOLLET | EPOLLERR | EPOLLHUP;
+	ev.data.ptr = NULL;
+	r = epoll_ctl(ctx.epfd, EPOLL_CTL_ADD, ctx.evfd, &ev);
+	ASSERT_EQ(r, 0);
+
+	/*
+	 * We are testing a race.  Repeat the test case 1000 times to make it
+	 * more likely to fail in case of a bug.
+	 */
+	for (i = 0; i < 1000; i++) {
+		pthread_t threads[3];
+		int n;
+
+		/*
+		 * Start 3 threads:
+		 * Thread 1 sleeps for 10.9ms and writes to the evenfd.
+		 * Thread 2 calls epoll with a timeout of 11ms.
+		 * Thread 3 calls epoll with a timeout of -1.
+		 *
+		 * The eventfd write by Thread 1 should either wakeup Thread 2
+		 * or Thread 3.  If it wakes up Thread 2, Thread 2 writes on the
+		 * eventfd to wake up Thread 3.
+		 *
+		 * If no events are missed, all three threads should eventually
+		 * be joinable.
+		 */
+		ASSERT_EQ(pthread_create(&threads[0], NULL,
+					 epoll61_write_eventfd, &ctx), 0);
+		ASSERT_EQ(pthread_create(&threads[1], NULL,
+					 epoll61_epoll_with_timeout, &ctx), 0);
+		ASSERT_EQ(pthread_create(&threads[2], NULL,
+					 epoll61_blocking_epoll, &ctx), 0);
+
+		for (n = 0; n < ARRAY_SIZE(threads); ++n)
+			ASSERT_EQ(pthread_join(threads[n], NULL), 0);
+	}
+
+	close(ctx.epfd);
+	close(ctx.evfd);
+}
+
+/* Equivalent to basic test epoll1, but exercising epoll_pwait2. */
+TEST(epoll62)
+{
+	int efd;
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ASSERT_EQ(write(sfd[1], "w", 1), 1);
+
+	EXPECT_EQ(sys_epoll_pwait2(efd, &e, 1, NULL, NULL, 0), 1);
+	EXPECT_EQ(sys_epoll_pwait2(efd, &e, 1, NULL, NULL, 0), 1);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/* Epoll_pwait2 basic timeout test. */
+TEST(epoll63)
+{
+	const int cfg_delay_ms = 10;
+	unsigned long long tdiff;
+	struct __kernel_timespec ts;
+	int efd;
+	int sfd[2];
+	struct epoll_event e;
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sfd), 0);
+
+	efd = epoll_create(1);
+	ASSERT_GE(efd, 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, sfd[0], &e), 0);
+
+	ts.tv_sec = 0;
+	ts.tv_nsec = cfg_delay_ms * 1000 * 1000;
+
+	tdiff = msecs();
+	EXPECT_EQ(sys_epoll_pwait2(efd, &e, 1, &ts, NULL, 0), 0);
+	tdiff = msecs() - tdiff;
+
+	EXPECT_GE(tdiff, cfg_delay_ms);
+
+	close(efd);
+	close(sfd[0]);
+	close(sfd[1]);
+}
+
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll64)
+{
+	pthread_t waiter[2];
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	/*
+	 * main will act as the emitter once both waiter threads are
+	 * blocked and expects to both be awoken upon the ready event.
+	 */
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&waiter[0], NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&waiter[1], NULL, waiter_entry1a, &ctx), 0);
+
+	usleep(100000);
+	ASSERT_EQ(write(ctx.sfd[1], "w", 1), 1);
+
+	ASSERT_EQ(pthread_join(waiter[0], NULL), 0);
+	ASSERT_EQ(pthread_join(waiter[1], NULL), 0);
+
+	EXPECT_EQ(ctx.count, 2);
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/filesystems/fat/.gitignore b/tools/testing/selftests/filesystems/fat/.gitignore
new file mode 100644
index 000000000..b89920ed8
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+rename_exchange
diff --git a/tools/testing/selftests/filesystems/fat/Makefile b/tools/testing/selftests/filesystems/fat/Makefile
new file mode 100644
index 000000000..902033f6e
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_PROGS := run_fat_tests.sh
+TEST_GEN_PROGS_EXTENDED := rename_exchange
+CFLAGS += -O2 -g -Wall $(KHDR_INCLUDES)
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/filesystems/fat/config b/tools/testing/selftests/filesystems/fat/config
new file mode 100644
index 000000000..6cf95e787
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/config
@@ -0,0 +1,2 @@
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_VFAT_FS=y
diff --git a/tools/testing/selftests/filesystems/fat/rename_exchange.c b/tools/testing/selftests/filesystems/fat/rename_exchange.c
new file mode 100644
index 000000000..e488ad354
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/rename_exchange.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Program that atomically exchanges two paths using
+ * the renameat2() system call RENAME_EXCHANGE flag.
+ *
+ * Copyright 2022 Red Hat Inc.
+ * Author: Javier Martinez Canillas <javierm@redhat.com>
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void print_usage(const char *program)
+{
+	printf("Usage: %s [oldpath] [newpath]\n", program);
+	printf("Atomically exchange oldpath and newpath\n");
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	if (argc != 3) {
+		print_usage(argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	ret = renameat2(AT_FDCWD, argv[1], AT_FDCWD, argv[2], RENAME_EXCHANGE);
+	if (ret) {
+		perror("rename exchange failed");
+		exit(EXIT_FAILURE);
+	}
+
+	exit(EXIT_SUCCESS);
+}
diff --git a/tools/testing/selftests/filesystems/fat/run_fat_tests.sh b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh
new file mode 100755
index 000000000..7f35dc3d1
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh
@@ -0,0 +1,82 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Run filesystem operations tests on an 1 MiB disk image that is formatted with
+# a vfat filesystem and mounted in a temporary directory using a loop device.
+#
+# Copyright 2022 Red Hat Inc.
+# Author: Javier Martinez Canillas <javierm@redhat.com>
+
+set -e
+set -u
+set -o pipefail
+
+BASE_DIR="$(dirname $0)"
+TMP_DIR="$(mktemp -d /tmp/fat_tests_tmp.XXXX)"
+IMG_PATH="${TMP_DIR}/fat.img"
+MNT_PATH="${TMP_DIR}/mnt"
+
+cleanup()
+{
+    mountpoint -q "${MNT_PATH}" && unmount_image
+    rm -rf "${TMP_DIR}"
+}
+trap cleanup SIGINT SIGTERM EXIT
+
+create_loopback()
+{
+    touch "${IMG_PATH}"
+    chattr +C "${IMG_PATH}" >/dev/null 2>&1 || true
+
+    truncate -s 1M "${IMG_PATH}"
+    mkfs.vfat "${IMG_PATH}" >/dev/null 2>&1
+}
+
+mount_image()
+{
+    mkdir -p "${MNT_PATH}"
+    sudo mount -o loop "${IMG_PATH}" "${MNT_PATH}"
+}
+
+rename_exchange_test()
+{
+    local rename_exchange="${BASE_DIR}/rename_exchange"
+    local old_path="${MNT_PATH}/old_file"
+    local new_path="${MNT_PATH}/new_file"
+
+    echo old | sudo tee "${old_path}" >/dev/null 2>&1
+    echo new | sudo tee "${new_path}" >/dev/null 2>&1
+    sudo "${rename_exchange}" "${old_path}" "${new_path}" >/dev/null 2>&1
+    sudo sync -f "${MNT_PATH}"
+    grep new "${old_path}" >/dev/null 2>&1
+    grep old "${new_path}" >/dev/null 2>&1
+}
+
+rename_exchange_subdir_test()
+{
+    local rename_exchange="${BASE_DIR}/rename_exchange"
+    local dir_path="${MNT_PATH}/subdir"
+    local old_path="${MNT_PATH}/old_file"
+    local new_path="${dir_path}/new_file"
+
+    sudo mkdir -p "${dir_path}"
+    echo old | sudo tee "${old_path}" >/dev/null 2>&1
+    echo new | sudo tee "${new_path}" >/dev/null 2>&1
+    sudo "${rename_exchange}" "${old_path}" "${new_path}" >/dev/null 2>&1
+    sudo sync -f "${MNT_PATH}"
+    grep new "${old_path}" >/dev/null 2>&1
+    grep old "${new_path}" >/dev/null 2>&1
+}
+
+unmount_image()
+{
+    sudo umount "${MNT_PATH}" &> /dev/null
+}
+
+create_loopback
+mount_image
+rename_exchange_test
+rename_exchange_subdir_test
+unmount_image
+
+exit 0