v4.19.13 snapshot.
diff --git a/arch/um/drivers/harddog_user.c b/arch/um/drivers/harddog_user.c
new file mode 100644
index 0000000..3aa8b0d
--- /dev/null
+++ b/arch/um/drivers/harddog_user.c
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <os.h>
+
+struct dog_data {
+ int stdin_fd;
+ int stdout_fd;
+ int close_me[2];
+};
+
+static void pre_exec(void *d)
+{
+ struct dog_data *data = d;
+
+ dup2(data->stdin_fd, 0);
+ dup2(data->stdout_fd, 1);
+ dup2(data->stdout_fd, 2);
+ close(data->stdin_fd);
+ close(data->stdout_fd);
+ close(data->close_me[0]);
+ close(data->close_me[1]);
+}
+
+int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock)
+{
+ struct dog_data data;
+ int in_fds[2], out_fds[2], pid, n, err;
+ char pid_buf[sizeof("nnnnnnn\0")], c;
+ char *pid_args[] = { "/usr/bin/uml_watchdog", "-pid", pid_buf, NULL };
+ char *mconsole_args[] = { "/usr/bin/uml_watchdog", "-mconsole", NULL,
+ NULL };
+ char **args = NULL;
+
+ err = os_pipe(in_fds, 1, 0);
+ if (err < 0) {
+ printk("harddog_open - os_pipe failed, err = %d\n", -err);
+ goto out;
+ }
+
+ err = os_pipe(out_fds, 1, 0);
+ if (err < 0) {
+ printk("harddog_open - os_pipe failed, err = %d\n", -err);
+ goto out_close_in;
+ }
+
+ data.stdin_fd = out_fds[0];
+ data.stdout_fd = in_fds[1];
+ data.close_me[0] = out_fds[1];
+ data.close_me[1] = in_fds[0];
+
+ if (sock != NULL) {
+ mconsole_args[2] = sock;
+ args = mconsole_args;
+ }
+ else {
+ /* XXX The os_getpid() is not SMP correct */
+ sprintf(pid_buf, "%d", os_getpid());
+ args = pid_args;
+ }
+
+ pid = run_helper(pre_exec, &data, args);
+
+ close(out_fds[0]);
+ close(in_fds[1]);
+
+ if (pid < 0) {
+ err = -pid;
+ printk("harddog_open - run_helper failed, errno = %d\n", -err);
+ goto out_close_out;
+ }
+
+ n = read(in_fds[0], &c, sizeof(c));
+ if (n == 0) {
+ printk("harddog_open - EOF on watchdog pipe\n");
+ helper_wait(pid);
+ err = -EIO;
+ goto out_close_out;
+ }
+ else if (n < 0) {
+ printk("harddog_open - read of watchdog pipe failed, "
+ "err = %d\n", errno);
+ helper_wait(pid);
+ err = n;
+ goto out_close_out;
+ }
+ *in_fd_ret = in_fds[0];
+ *out_fd_ret = out_fds[1];
+ return 0;
+
+ out_close_in:
+ close(in_fds[0]);
+ close(in_fds[1]);
+ out_close_out:
+ close(out_fds[0]);
+ close(out_fds[1]);
+ out:
+ return err;
+}
+
+void stop_watchdog(int in_fd, int out_fd)
+{
+ close(in_fd);
+ close(out_fd);
+}
+
+int ping_watchdog(int fd)
+{
+ int n;
+ char c = '\n';
+
+ n = write(fd, &c, sizeof(c));
+ if (n != sizeof(c)) {
+ printk("ping_watchdog - write failed, ret = %d, err = %d\n",
+ n, errno);
+ if (n < 0)
+ return n;
+ return -EIO;
+ }
+ return 1;
+
+}