tty: Move the handling of the tty release logic

Now that we don't have tty->termios tied to drivers->tty we can untangle
the logic here. In addition we can push the removal logic out of the
destructor path.

At that point we can think about sorting out tty_port and console and all
the other ugly hangovers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 31 insertions, 41 deletions

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 5ad7ccc49f7..60c08ce8378 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -527,12 +527,6 @@ static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
         return tty;
 }
 
-static void pty_unix98_shutdown(struct tty_struct *tty)
-{
-        tty_driver_remove_tty(tty->driver, tty);
-        /* We have our own method as we don't use the tty index */
-}
-
 /* We have no need to install and remove our tty objects as devpts does all
    the work for us */
 
@@ -558,9 +552,8 @@ static const struct tty_operations ptm_unix98_ops = {
         .unthrottle = pty_unthrottle,
         .set_termios = pty_set_termios,
         .ioctl = pty_unix98_ioctl,
-        .shutdown = pty_unix98_shutdown,
-        .cleanup = pty_cleanup,
-        .resize = pty_resize
+        .resize = pty_resize,
+        .cleanup = pty_cleanup
 };
 
 static const struct tty_operations pty_unix98_ops = {
@@ -575,7 +568,6 @@ static const struct tty_operations pty_unix98_ops = {
         .chars_in_buffer = pty_chars_in_buffer,
         .unthrottle = pty_unthrottle,
         .set_termios = pty_set_termios,
-        .shutdown = pty_unix98_shutdown,
         .cleanup = pty_cleanup,
 };
 
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index cfd12da8121..be18d60ddf4 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1249,16 +1249,16 @@ int tty_init_termios(struct tty_struct *tty)
         struct ktermios *tp;
         int idx = tty->index;
 
-        tp = tty->driver->termios[idx];
-        if (tp == NULL) {
-                tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
-                if (tp == NULL)
-                        return -ENOMEM;
-                *tp = tty->driver->init_termios;
-                tty->driver->termios[idx] = tp;
+        if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
+                tty->termios = tty->driver->init_termios;
+        else {
+                /* Check for lazy saved data */
+                tp = tty->driver->termios[idx];
+                if (tp != NULL)
+                        tty->termios = *tp;
+                else
+                        tty->termios = tty->driver->init_termios;
         }
-        tty->termios = *tp;
-
         /* Compatibility until drivers always set this */
         tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
         tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
@@ -1437,24 +1437,24 @@ void tty_free_termios(struct tty_struct *tty)
 {
         struct ktermios *tp;
         int idx = tty->index;
-        /* Kill this flag and push into drivers for locking etc */
-        if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
-                /* FIXME: Locking on ->termios array */
-                tp = tty->driver->termios[idx];
-                tty->driver->termios[idx] = NULL;
-                kfree(tp);
+
+        /* If the port is going to reset then it has no termios to save */
+        if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
+                return;
+
+        /* Stash the termios data */
+        tp = tty->driver->termios[idx];
+        if (tp == NULL) {
+                tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+                if (tp == NULL) {
+                        pr_warn("tty: no memory to save termios state.\n");
+                        return;
+                }
         }
-        else
-                *tty->driver->termios[idx] = tty->termios;
+        *tp = tty->termios;
 }
 EXPORT_SYMBOL(tty_free_termios);
 
-void tty_shutdown(struct tty_struct *tty)
-{
-        tty_driver_remove_tty(tty->driver, tty);
-        tty_free_termios(tty);
-}
-EXPORT_SYMBOL(tty_shutdown);
 
 /**
  *      release_one_tty         -       release tty structure memory
@@ -1498,11 +1498,6 @@ static void queue_release_one_tty(struct kref *kref)
 {
         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
 
-        if (tty->ops->shutdown)
-                tty->ops->shutdown(tty);
-        else
-                tty_shutdown(tty);
-
         /* The hangup queue is now free so we can reuse it rather than
            waste a chunk of memory for each port */
         INIT_WORK(&tty->hangup_work, release_one_tty);
@@ -1542,6 +1537,11 @@ static void release_tty(struct tty_struct *tty, int idx)
         /* This should always be true but check for the moment */
         WARN_ON(tty->index != idx);
 
+        if (tty->ops->shutdown)
+                tty->ops->shutdown(tty);
+        tty_free_termios(tty);
+        tty_driver_remove_tty(tty->driver, tty);
+
         if (tty->link)
                 tty_kref_put(tty->link);
         tty_kref_put(tty);
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index dbceaeb2c3e..e07ded30fc7 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2850,7 +2850,6 @@ static void con_shutdown(struct tty_struct *tty)
         console_lock();
         vc->port.tty = NULL;
         console_unlock();
-        tty_shutdown(tty);
 }
 
 static int default_italic_color    = 2; // green (ASCII)
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 5fe21357b55..aa4b0d77599 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -305,8 +305,7 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
  * Do the resource freeing and refcount dropping for the port.
  * Avoid freeing the console.
  *
- * Called asynchronously after the last tty kref is dropped,
- * and the tty layer has already done the tty_shutdown(tty);
+ * Called asynchronously after the last tty kref is dropped.
  */
 static void serial_cleanup(struct tty_struct *tty)
 {