v4.19.13 snapshot.
diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
new file mode 100644
index 0000000..3fd7c3e
--- /dev/null
+++ b/arch/um/drivers/chan_user.c
@@ -0,0 +1,301 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include "chan_user.h"
+#include <os.h>
+#include <um_malloc.h>
+
+void generic_close(int fd, void *unused)
+{
+ close(fd);
+}
+
+int generic_read(int fd, char *c_out, void *unused)
+{
+ int n;
+
+ n = read(fd, c_out, sizeof(*c_out));
+ if (n > 0)
+ return n;
+ else if (errno == EAGAIN)
+ return 0;
+ else if (n == 0)
+ return -EIO;
+ return -errno;
+}
+
+/* XXX Trivial wrapper around write */
+
+int generic_write(int fd, const char *buf, int n, void *unused)
+{
+ int err;
+
+ err = write(fd, buf, n);
+ if (err > 0)
+ return err;
+ else if (errno == EAGAIN)
+ return 0;
+ else if (err == 0)
+ return -EIO;
+ return -errno;
+}
+
+int generic_window_size(int fd, void *unused, unsigned short *rows_out,
+ unsigned short *cols_out)
+{
+ struct winsize size;
+ int ret;
+
+ if (ioctl(fd, TIOCGWINSZ, &size) < 0)
+ return -errno;
+
+ ret = ((*rows_out != size.ws_row) || (*cols_out != size.ws_col));
+
+ *rows_out = size.ws_row;
+ *cols_out = size.ws_col;
+
+ return ret;
+}
+
+void generic_free(void *data)
+{
+ kfree(data);
+}
+
+int generic_console_write(int fd, const char *buf, int n)
+{
+ sigset_t old, no_sigio;
+ struct termios save, new;
+ int err;
+
+ if (isatty(fd)) {
+ sigemptyset(&no_sigio);
+ sigaddset(&no_sigio, SIGIO);
+ if (sigprocmask(SIG_BLOCK, &no_sigio, &old))
+ goto error;
+
+ CATCH_EINTR(err = tcgetattr(fd, &save));
+ if (err)
+ goto error;
+ new = save;
+ /*
+ * The terminal becomes a bit less raw, to handle \n also as
+ * "Carriage Return", not only as "New Line". Otherwise, the new
+ * line won't start at the first column.
+ */
+ new.c_oflag |= OPOST;
+ CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new));
+ if (err)
+ goto error;
+ }
+ err = generic_write(fd, buf, n, NULL);
+ /*
+ * Restore raw mode, in any case; we *must* ignore any error apart
+ * EINTR, except for debug.
+ */
+ if (isatty(fd)) {
+ CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save));
+ sigprocmask(SIG_SETMASK, &old, NULL);
+ }
+
+ return err;
+error:
+ return -errno;
+}
+
+/*
+ * UML SIGWINCH handling
+ *
+ * The point of this is to handle SIGWINCH on consoles which have host
+ * ttys and relay them inside UML to whatever might be running on the
+ * console and cares about the window size (since SIGWINCH notifies
+ * about terminal size changes).
+ *
+ * So, we have a separate thread for each host tty attached to a UML
+ * device (side-issue - I'm annoyed that one thread can't have
+ * multiple controlling ttys for the purpose of handling SIGWINCH, but
+ * I imagine there are other reasons that doesn't make any sense).
+ *
+ * SIGWINCH can't be received synchronously, so you have to set up to
+ * receive it as a signal. That being the case, if you are going to
+ * wait for it, it is convenient to sit in sigsuspend() and wait for
+ * the signal to bounce you out of it (see below for how we make sure
+ * to exit only on SIGWINCH).
+ */
+
+static void winch_handler(int sig)
+{
+}
+
+struct winch_data {
+ int pty_fd;
+ int pipe_fd;
+};
+
+static int winch_thread(void *arg)
+{
+ struct winch_data *data = arg;
+ sigset_t sigs;
+ int pty_fd, pipe_fd;
+ int count;
+ char c = 1;
+
+ pty_fd = data->pty_fd;
+ pipe_fd = data->pipe_fd;
+ count = write(pipe_fd, &c, sizeof(c));
+ if (count != sizeof(c))
+ printk(UM_KERN_ERR "winch_thread : failed to write "
+ "synchronization byte, err = %d\n", -count);
+
+ /*
+ * We are not using SIG_IGN on purpose, so don't fix it as I thought to
+ * do! If using SIG_IGN, the sigsuspend() call below would not stop on
+ * SIGWINCH.
+ */
+
+ signal(SIGWINCH, winch_handler);
+ sigfillset(&sigs);
+ /* Block all signals possible. */
+ if (sigprocmask(SIG_SETMASK, &sigs, NULL) < 0) {
+ printk(UM_KERN_ERR "winch_thread : sigprocmask failed, "
+ "errno = %d\n", errno);
+ exit(1);
+ }
+ /* In sigsuspend(), block anything else than SIGWINCH. */
+ sigdelset(&sigs, SIGWINCH);
+
+ if (setsid() < 0) {
+ printk(UM_KERN_ERR "winch_thread : setsid failed, errno = %d\n",
+ errno);
+ exit(1);
+ }
+
+ if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) {
+ printk(UM_KERN_ERR "winch_thread : TIOCSCTTY failed on "
+ "fd %d err = %d\n", pty_fd, errno);
+ exit(1);
+ }
+
+ if (tcsetpgrp(pty_fd, os_getpid()) < 0) {
+ printk(UM_KERN_ERR "winch_thread : tcsetpgrp failed on "
+ "fd %d err = %d\n", pty_fd, errno);
+ exit(1);
+ }
+
+ /*
+ * These are synchronization calls between various UML threads on the
+ * host - since they are not different kernel threads, we cannot use
+ * kernel semaphores. We don't use SysV semaphores because they are
+ * persistent.
+ */
+ count = read(pipe_fd, &c, sizeof(c));
+ if (count != sizeof(c))
+ printk(UM_KERN_ERR "winch_thread : failed to read "
+ "synchronization byte, err = %d\n", errno);
+
+ while(1) {
+ /*
+ * This will be interrupted by SIGWINCH only, since
+ * other signals are blocked.
+ */
+ sigsuspend(&sigs);
+
+ count = write(pipe_fd, &c, sizeof(c));
+ if (count != sizeof(c))
+ printk(UM_KERN_ERR "winch_thread : write failed, "
+ "err = %d\n", errno);
+ }
+}
+
+static int winch_tramp(int fd, struct tty_port *port, int *fd_out,
+ unsigned long *stack_out)
+{
+ struct winch_data data;
+ int fds[2], n, err;
+ char c;
+
+ err = os_pipe(fds, 1, 1);
+ if (err < 0) {
+ printk(UM_KERN_ERR "winch_tramp : os_pipe failed, err = %d\n",
+ -err);
+ goto out;
+ }
+
+ data = ((struct winch_data) { .pty_fd = fd,
+ .pipe_fd = fds[1] } );
+ /*
+ * CLONE_FILES so this thread doesn't hold open files which are open
+ * now, but later closed in a different thread. This is a
+ * problem with /dev/net/tun, which if held open by this
+ * thread, prevents the TUN/TAP device from being reused.
+ */
+ err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);
+ if (err < 0) {
+ printk(UM_KERN_ERR "fork of winch_thread failed - errno = %d\n",
+ -err);
+ goto out_close;
+ }
+
+ *fd_out = fds[0];
+ n = read(fds[0], &c, sizeof(c));
+ if (n != sizeof(c)) {
+ printk(UM_KERN_ERR "winch_tramp : failed to read "
+ "synchronization byte\n");
+ printk(UM_KERN_ERR "read failed, err = %d\n", errno);
+ printk(UM_KERN_ERR "fd %d will not support SIGWINCH\n", fd);
+ err = -EINVAL;
+ goto out_close;
+ }
+
+ if (os_set_fd_block(*fd_out, 0)) {
+ printk(UM_KERN_ERR "winch_tramp: failed to set thread_fd "
+ "non-blocking.\n");
+ goto out_close;
+ }
+
+ return err;
+
+ out_close:
+ close(fds[1]);
+ close(fds[0]);
+ out:
+ return err;
+}
+
+void register_winch(int fd, struct tty_port *port)
+{
+ unsigned long stack;
+ int pid, thread, count, thread_fd = -1;
+ char c = 1;
+
+ if (!isatty(fd))
+ return;
+
+ pid = tcgetpgrp(fd);
+ if (is_skas_winch(pid, fd, port)) {
+ register_winch_irq(-1, fd, -1, port, 0);
+ return;
+ }
+
+ if (pid == -1) {
+ thread = winch_tramp(fd, port, &thread_fd, &stack);
+ if (thread < 0)
+ return;
+
+ register_winch_irq(thread_fd, fd, thread, port, stack);
+
+ count = write(thread_fd, &c, sizeof(c));
+ if (count != sizeof(c))
+ printk(UM_KERN_ERR "register_winch : failed to write "
+ "synchronization byte, err = %d\n", errno);
+ }
+}