Fix exit_group not interrupt wait4

src/libos/src/process/do_exit.rs

@@ -19,6 +19,15 @@ pub fn do_exit_group(status: i32, curr_user_ctxt: &mut CpuContext) -> Result<isi
     } else {
         let term_status = TermStatus::Exited(status as u8);
         current!().process().force_exit(term_status);
+
+        // wake all child threads which are waiting
+        let _ = current!()
+            .process()
+            .inner()
+            .waiting_children_mut()
+            .unwrap()
+            .del_and_wake_all_waiters();
+
         exit_thread(term_status);
         Ok(0)
     }

src/libos/src/process/do_wait4.rs

@@ -88,11 +88,14 @@ pub fn do_wait4(child_filter: &ProcessFilter, options: WaitOptions) -> Result<(p
     // without risking missing events from the process's children.
     drop(process_inner);
     // Wait until a child has interesting events
-    let zombie_pid = waiter.sleep_until_woken_with_result();
-
-    let mut process_inner = process.inner();
-    let exit_status = free_zombie_child(process_inner, zombie_pid);
-    Ok((zombie_pid, exit_status))
+    if let Some(zombie_pid) = waiter.sleep_until_woken_with_result() {
+        let mut process_inner = process.inner();
+        let exit_status = free_zombie_child(process_inner, zombie_pid);
+        Ok((zombie_pid, exit_status))
+    } else {
+        // The wait is interrupted
+        return_errno!(EINTR, "wait is interrupted and not get any children");
+    }
 }
 
 fn free_zombie_child(mut parent_inner: SgxMutexGuard<ProcessInner>, zombie_pid: pid_t) -> i32 {

src/libos/src/process/wait.rs

@@ -51,14 +51,14 @@ where
         self.inner.lock().unwrap().data
     }
 
-    pub fn sleep_until_woken_with_result(self) -> R {
+    pub fn sleep_until_woken_with_result(self) -> Option<R> {
         while !self.inner.lock().unwrap().is_woken {
             unsafe {
                 wait_event(self.thread);
             }
         }
 
-        self.inner.lock().unwrap().result.unwrap()
+        self.inner.lock().unwrap().result
     }
 }
 
@@ -114,4 +114,17 @@ where
         set_event(del_waiter.thread);
         1
     }
+
+    pub fn del_and_wake_all_waiters(&mut self) -> usize {
+        let mut waiters = &mut self.waiters;
+        let ret = waiters.len();
+        waiters.drain(..).for_each(|waiter| {
+            let mut waiter_inner = waiter.inner.lock().unwrap();
+            waiter_inner.is_woken = true;
+            waiter_inner.result = None;
+            set_event(waiter.thread);
+        });
+
+        ret
+    }
 }

test/client/main.c

@@ -9,6 +9,7 @@
 #include <arpa/inet.h>
 #include <spawn.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 #include "test.h"
 
@@ -159,6 +160,28 @@ int client_connectionless_sendmsg(char *buf) {
     return ret;
 }
 
+int blocking_recvfrom(int server_fd, char *buf, int buf_size) {
+    int flags = fcntl(server_fd, F_GETFL, 0);
+    if (flags == -1) {
+        THROW_ERROR("fnctl failed");
+    }
+    flags = flags & ~O_NONBLOCK;
+    fcntl(server_fd, F_SETFL, flags);
+    if (flags == -1) {
+        THROW_ERROR("fnctl failed");
+    }
+
+    // wait for server to exit and the remote end is closed
+    sleep(1);
+    printf("client blocking recvfrom\n");
+    int ret = recvfrom(server_fd, buf, buf_size, 0, NULL, 0);
+    if (ret >= 0 || errno != ECONNRESET) {
+        THROW_ERROR("recvfrom failed");
+    }
+
+    return 0;
+}
+
 int main(int argc, const char *argv[]) {
     if (argc != 3) {
         THROW_ERROR("usage: ./client <ipaddress> <port>\n");
@@ -190,6 +213,17 @@ int main(int argc, const char *argv[]) {
         case 8804:
             ret = client_connectionless_sendmsg(DEFAULT_MSG);
             break;
+        case 8888:
+            neogotiate_msg(server_fd, buf, buf_size);
+            ret = client_sendmsg(server_fd, buf);
+            if (ret < 0) {
+                THROW_ERROR("client sendmsg failed");
+            }
+            ret = blocking_recvfrom(server_fd, buf, buf_size);
+            if (ret < 0) {
+                THROW_ERROR("client blocking recvfrom failed");
+            }
+            break;
         default:
             ret = client_send(server_fd, DEFAULT_MSG);
     }

test/server/Makefile

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

test/server/main.c

@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
@@ -11,6 +12,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <pthread.h>
 
 #include "test.h"
 
@@ -209,6 +211,14 @@ int wait_for_child_exit(int child_pid) {
     return 0;
 }
 
+static void *thread_wait_func(void *_arg) {
+    pid_t *client_pid = _arg;
+
+    waitpid(*client_pid, NULL, 0);
+
+    return NULL;
+}
+
 int test_read_write() {
     int ret = 0;
     int child_pid = 0;
@@ -403,6 +413,93 @@ int test_poll() {
     return 0;
 }
 
+// This is a testcase mocking pyspark exit procedure. Client process is receiving and blocking.
+// One of server process' child thread waits for the client to exit and the main thread calls exit_group.
+static int test_exit_group() {
+    int port = 8888;
+    int pipes[2];
+    int ret = 0;
+    int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
+    if (listen_fd < 0) {
+        THROW_ERROR("create socket error");
+    }
+
+    ret = pipe2(pipes, 0);
+    if (ret < 0) {
+        THROW_ERROR("error happens");
+    }
+
+    printf("pipe fd = %d, %d\n", pipes[0], pipes[1]);
+
+    int child_pid = vfork();
+    if (child_pid == 0) {
+        ret = close(pipes[1]);
+        if (ret < 0) {
+            THROW_ERROR("error happens");
+        }
+        ret = dup2(pipes[0], 0);
+        if (ret < 0) {
+            THROW_ERROR("error happens");
+        }
+
+        ret = close(pipes[0]);
+        if (ret < 0) {
+            THROW_ERROR("error happens");
+        }
+
+        char port_string[8];
+        sprintf(port_string, "%d", port);
+        char *client_argv[] = {"client", "127.0.0.1", port_string, NULL};
+        printf("exec child\n");
+        execve("/bin/client", client_argv, NULL);
+    }
+
+    printf("return to parent\n");
+    close(pipes[0]);
+
+    int reuse = 1;
+    if (setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0) {
+        THROW_ERROR("setsockopt port to reuse failed");
+    }
+
+    struct sockaddr_in servaddr;
+    memset(&servaddr, 0, sizeof(servaddr));
+    servaddr.sin_family = AF_INET;
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+    servaddr.sin_port = htons(port);
+    ret = bind(listen_fd, (struct sockaddr *) &servaddr, sizeof(servaddr));
+    if (ret < 0) {
+        close(listen_fd);
+        THROW_ERROR("bind socket failed");
+    }
+
+    ret = listen(listen_fd, 5);
+    if (ret < 0) {
+        close(listen_fd);
+        THROW_ERROR("listen socket error");
+    }
+
+    int connected_fd = accept(listen_fd, (struct sockaddr *) NULL, NULL); // 4
+    if (connected_fd < 0) {
+        close(listen_fd);
+        THROW_ERROR("accept socket error");
+    }
+
+    if (neogotiate_msg(connected_fd) < 0) {
+        THROW_ERROR("neogotiate failed");
+    }
+
+    pthread_t tid;
+    ret = pthread_create(&tid, NULL, thread_wait_func, &child_pid);
+    if (ret != 0) {
+        THROW_ERROR("create child error");
+    }
+
+    // Wait a while here for client to call recvfrom and blocking
+    sleep(2);
+    return 0;
+}
+
 static test_case_t test_cases[] = {
     TEST_CASE(test_read_write),
     TEST_CASE(test_send_recv),
@@ -414,6 +511,7 @@ static test_case_t test_cases[] = {
     TEST_CASE(test_fcntl_setfl_and_getfl),
     TEST_CASE(test_poll),
     TEST_CASE(test_poll_events_unchanged),
+    TEST_CASE(test_exit_group),
 };
 
 int main(int argc, const char *argv[]) {