Fix epoll_ctl not waking up epoll_wait

Co-authored-by: rduan@apache.org

src/libos/src/net/io_multiplexing/epoll/epoll_file.rs

@@ -312,9 +312,6 @@ impl EpollFile {
 
             let new_ep_inner = EpollEntryInner { event, flags };
             let mut old_ep_inner = ep_entry.inner.lock().unwrap();
-            if *old_ep_inner == new_ep_inner {
-                return Ok(());
-            }
             *old_ep_inner = new_ep_inner;
             drop(old_ep_inner);
 

test/Makefile

@@ -22,7 +22,7 @@ TESTS ?= env empty hello_world malloc mmap file fs_perms getpid spawn sched pipe
 	truncate readdir mkdir open stat link symlink chmod chown tls pthread system_info rlimit \
 	server server_epoll unix_socket cout hostfs cpuid rdtsc device sleep exit_group posix_flock \
 	ioctl fcntl eventfd emulate_syscall access signal sysinfo prctl rename procfs wait \
-	spawn_attribute exec statfs random umask pgrp vfork mount flock utimes shm
+	spawn_attribute exec statfs random umask pgrp vfork mount flock utimes shm epoll
 # Benchmarks: need to be compiled and run by bench-% target
 BENCHES := spawn_and_exit_latency pipe_throughput unix_socket_throughput
 

test/epoll/Makefile

@@ -0,0 +1,5 @@
+include ../test_common.mk
+
+EXTRA_C_FLAGS :=
+EXTRA_LINK_FLAGS := -lpthread
+BIN_ARGS :=

test/epoll/main.c

@@ -0,0 +1,177 @@
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <poll.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <spawn.h>
+#include <string.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <pthread.h>
+#include "test.h"
+
+// ============================================================================
+// Helper definition
+// ============================================================================
+
+#define MAXEVENTS 64
+#define TEST_DATA 678
+
+struct thread_arg {
+    pthread_t tid;
+    int fd;
+    uint64_t data;
+};
+
+// ============================================================================
+// Helper functions
+// ============================================================================
+
+static void *thread_child(void *arg) {
+    struct thread_arg *child_arg = arg;
+
+    printf("epoll_wait 1...\n");
+    struct epoll_event events[MAXEVENTS] = {0};
+    int nfds = epoll_wait(child_arg->fd, events, MAXEVENTS, -1);
+    if (nfds < 0) {
+        return (void *) -1;
+    }
+    printf("epoll_wait 1 success.\n");
+
+    sleep(1);
+
+    printf("epoll_wait 2...\n");
+    nfds = epoll_wait(child_arg->fd, events, MAXEVENTS, -1);
+    if (nfds < 0) {
+        return (void *) -1;
+    }
+    printf("epoll_wait 2 success.\n");
+    return NULL;
+}
+
+int create_child(struct thread_arg *arg) {
+    pthread_attr_t attr;
+    if (pthread_attr_init(&attr) != 0) {
+        THROW_ERROR("failed to initialize attribute");
+    }
+
+    if (pthread_create(&(arg->tid), &attr, &thread_child, arg) != 0) {
+        if (pthread_attr_destroy(&attr) != 0) {
+            THROW_ERROR("failed to destroy attr");
+        }
+        THROW_ERROR("failed to create the thread");
+    }
+
+    if (pthread_attr_destroy(&attr) != 0) {
+        THROW_ERROR("failed to destroy attr");
+    }
+
+    return 0;
+}
+
+// This test intends to test that the epoll_wait can be waken epoll_ctl
+int test_epoll_ctl_main(int end_fd_1, int end_fd_2) {
+    uint64_t data = TEST_DATA;
+    struct thread_arg child_arg;
+
+    int epfd = epoll_create1(0);
+    if (epfd == -1) {
+        THROW_ERROR("epoll_create failed");
+    }
+
+    // watch for end_fd_1
+    struct epoll_event event;
+    event.data.fd = end_fd_1;
+    event.events = EPOLLIN | EPOLLET;
+    int ret = epoll_ctl(epfd, EPOLL_CTL_ADD, end_fd_1, &event);
+    if (ret == -1) {
+        close(epfd);
+        THROW_ERROR("epoll_ctl add failed");
+    }
+
+    // write to end_fd_2
+    int write_size = write(end_fd_2, &data, sizeof(data));
+    if (write_size < 0) {
+        THROW_ERROR("failed to write an eventfd");
+    }
+
+    child_arg.data = 0;
+    child_arg.fd = epfd;
+    child_arg.tid = 0;
+    if (create_child(&child_arg) != 0) {
+        close(epfd);
+        THROW_ERROR("failed to create children");
+    }
+
+    // wait for child thread to start second time epoll_wait
+    sleep(3);
+
+    printf("second time epoll ctl\n");
+    ret = epoll_ctl(epfd, EPOLL_CTL_MOD, end_fd_1, &event);
+    if (ret == -1) {
+        close(epfd);
+        THROW_ERROR("epoll_ctl mod failed");
+    }
+
+    pthread_join(child_arg.tid, NULL);
+    close(epfd);
+
+    return 0;
+}
+
+// ============================================================================
+// Test cases for anonymous mmap
+// ============================================================================
+
+int test_epoll_ctl_uds() {
+    int sockets[2];
+
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) < 0) {
+        THROW_ERROR("opening stream socket pair");
+    }
+
+    int ret = test_epoll_ctl_main(sockets[0], sockets[1]);
+    close(sockets[0]);
+    close(sockets[1]);
+
+    if (ret < 0) {
+        THROW_ERROR("epoll ctl test eventfd failure");
+    }
+
+    return 0;
+}
+
+int test_epoll_ctl_eventfd() {
+    int event_fd = eventfd(0, EFD_NONBLOCK);
+    if (event_fd < 0) {
+        THROW_ERROR("failed to create an eventfd");
+    }
+
+    int ret = test_epoll_ctl_main(event_fd, event_fd);
+    close(event_fd);
+
+    if (ret < 0) {
+        THROW_ERROR("epoll ctl test eventfd failure");
+    }
+    return 0;
+}
+
+// ============================================================================
+// Test suite main
+// ============================================================================
+
+static test_case_t test_cases[] = {
+    TEST_CASE(test_epoll_ctl_eventfd),
+    TEST_CASE(test_epoll_ctl_uds),
+};
+
+int main() {
+    return test_suite_run(test_cases, ARRAY_SIZE(test_cases));
+}