+/**
+ * ptm_unix98_lookup - find a pty master
+ * @driver: ptm driver
+ * @idx: tty index
+ *
+ * Look up a pty master device. Called under the tty_mutex for now.
+ * This provides our locking.
+ */
+
+static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
+ struct inode *ptm_inode, int idx)
+{
+ struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
+ if (tty)
+ tty = tty->link;
+ return tty;
+}
+
+/**
+ * pts_unix98_lookup - find a pty slave
+ * @driver: pts driver
+ * @idx: tty index
+ *
+ * Look up a pty master device. Called under the tty_mutex for now.
+ * This provides our locking.
+ */
+
+static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
+ struct inode *pts_inode, int idx)
+{
+ struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
+ /* Master must be open before slave */
+ if (!tty)
+ return ERR_PTR(-EIO);
+ return tty;
+}
+
+static void pty_unix98_shutdown(struct tty_struct *tty)
+{
+ /* We have our own method as we don't use the tty index */
+ kfree(tty->termios);
+}
+
+/* We have no need to install and remove our tty objects as devpts does all
+ the work for us */
+
+static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ struct tty_struct *o_tty;
+ int idx = tty->index;
+
+ o_tty = alloc_tty_struct();
+ if (!o_tty)
+ return -ENOMEM;
+ if (!try_module_get(driver->other->owner)) {
+ /* This cannot in fact currently happen */
+ free_tty_struct(o_tty);
+ return -ENOMEM;
+ }
+ initialize_tty_struct(o_tty, driver->other, idx);
+
+ tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
+ if (tty->termios == NULL)
+ goto free_mem_out;
+ *tty->termios = driver->init_termios;
+ tty->termios_locked = tty->termios + 1;
+
+ o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
+ if (o_tty->termios == NULL)
+ goto free_mem_out;
+ *o_tty->termios = driver->other->init_termios;
+ o_tty->termios_locked = o_tty->termios + 1;
+
+ tty_driver_kref_get(driver->other);
+ if (driver->subtype == PTY_TYPE_MASTER)
+ o_tty->count++;
+ /* Establish the links in both directions */
+ tty->link = o_tty;
+ o_tty->link = tty;
+ /*
+ * All structures have been allocated, so now we install them.
+ * Failures after this point use release_tty to clean up, so
+ * there's no need to null out the local pointers.
+ */
+ tty_driver_kref_get(driver);
+ tty->count++;
+ pty_count++;
+ return 0;
+free_mem_out:
+ kfree(o_tty->termios);
+ module_put(o_tty->driver->owner);
+ free_tty_struct(o_tty);
+ kfree(tty->termios);
+ return -ENOMEM;
+}
+
+static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
+{
+ pty_count--;
+}
+
+static const struct tty_operations ptm_unix98_ops = {
+ .lookup = ptm_unix98_lookup,
+ .install = pty_unix98_install,
+ .remove = pty_unix98_remove,
+ .open = pty_open,
+ .close = pty_close,
+ .write = pty_write,
+ .write_room = pty_write_room,
+ .flush_buffer = pty_flush_buffer,
+ .chars_in_buffer = pty_chars_in_buffer,
+ .unthrottle = pty_unthrottle,
+ .set_termios = pty_set_termios,
+ .ioctl = pty_unix98_ioctl,
+ .shutdown = pty_unix98_shutdown,
+ .resize = pty_resize
+};
+
+static const struct tty_operations pty_unix98_ops = {
+ .lookup = pts_unix98_lookup,
+ .install = pty_unix98_install,
+ .remove = pty_unix98_remove,
+ .open = pty_open,
+ .close = pty_close,
+ .write = pty_write,
+ .write_room = pty_write_room,
+ .flush_buffer = pty_flush_buffer,
+ .chars_in_buffer = pty_chars_in_buffer,
+ .unthrottle = pty_unthrottle,
+ .set_termios = pty_set_termios,
+ .shutdown = pty_unix98_shutdown
+};
+
+/**
+ * ptmx_open - open a unix 98 pty master
+ * @inode: inode of device file
+ * @filp: file pointer to tty
+ *
+ * Allocate a unix98 pty master device from the ptmx driver.
+ *
+ * Locking: tty_mutex protects the init_dev work. tty->count should
+ * protect the rest.
+ * allocated_ptys_lock handles the list of free pty numbers
+ */
+
+static int __ptmx_open(struct inode *inode, struct file *filp)
+{
+ struct tty_struct *tty;
+ int retval;
+ int index;
+
+ nonseekable_open(inode, filp);
+
+ /* find a device that is not in use. */
+ index = devpts_new_index(inode);
+ if (index < 0)
+ return index;
+
+ mutex_lock(&tty_mutex);
+ tty = tty_init_dev(ptm_driver, index, 1);
+ mutex_unlock(&tty_mutex);
+
+ if (IS_ERR(tty)) {
+ retval = PTR_ERR(tty);
+ goto out;
+ }
+
+ set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
+ filp->private_data = tty;
+ file_move(filp, &tty->tty_files);
+
+ retval = devpts_pty_new(inode, tty->link);
+ if (retval)
+ goto out1;
+
+ retval = ptm_driver->ops->open(tty, filp);
+ if (!retval)
+ return 0;
+out1:
+ tty_release_dev(filp);
+ return retval;
+out:
+ devpts_kill_index(inode, index);
+ return retval;
+}
+
+static int ptmx_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ lock_kernel();
+ ret = __ptmx_open(inode, filp);
+ unlock_kernel();
+ return ret;
+}
+
+static struct file_operations ptmx_fops;
+