---

yaml
---
r: 325622
b: refs/heads/master
c: d155255
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 373f5aedbc6fb73d30f00eeb0dc7313ecfede908
+refs/heads/master: d155255a344c417acad74156654295a2964e6b81

trunk/drivers/tty/pty.c

@@ -282,6 +282,17 @@ int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 	return 0;
 }
 
+/**
+ *	pty_common_install		-	set up the pty pair
+ *	@driver: the pty driver
+ *	@tty: the tty being instantiated
+ *	@bool: legacy, true if this is BSD style
+ *
+ *	Perform the initial set up for the tty/pty pair. Called from the
+ *	tty layer when the port is first opened.
+ *
+ *	Locking: the caller must hold the tty_mutex
+ */
 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 		bool legacy)
 {
@@ -364,6 +375,14 @@ static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 	return pty_common_install(driver, tty, true);
 }
 
+static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct tty_struct *pair = tty->link;
+	driver->ttys[tty->index] = NULL;
+	if (pair)
+		pair->driver->ttys[pair->index] = NULL;
+}
+
 static int pty_bsd_ioctl(struct tty_struct *tty,
 			 unsigned int cmd, unsigned long arg)
 {
@@ -395,7 +414,8 @@ static const struct tty_operations master_pty_ops_bsd = {
 	.set_termios = pty_set_termios,
 	.ioctl = pty_bsd_ioctl,
 	.cleanup = pty_cleanup,
-	.resize = pty_resize
+	.resize = pty_resize,
+	.remove = pty_remove
 };
 
 static const struct tty_operations slave_pty_ops_bsd = {
@@ -409,7 +429,8 @@ static const struct tty_operations slave_pty_ops_bsd = {
 	.unthrottle = pty_unthrottle,
 	.set_termios = pty_set_termios,
 	.cleanup = pty_cleanup,
-	.resize = pty_resize
+	.resize = pty_resize,
+	.remove = pty_remove
 };
 
 static void __init legacy_pty_init(void)

trunk/drivers/tty/tty_io.c

@@ -1465,7 +1465,6 @@ EXPORT_SYMBOL(tty_free_termios);
  *	in use. It also gets called when setup of a device fails.
  *
  *	Locking:
- *		tty_mutex - sometimes only
  *		takes the file list lock internally when working on the list
  *	of ttys that the driver keeps.
  *
@@ -1526,17 +1525,16 @@ EXPORT_SYMBOL(tty_kref_put);
  *	and decrement the refcount of the backing module.
  *
  *	Locking:
- *		tty_mutex - sometimes only
+ *		tty_mutex
  *		takes the file list lock internally when working on the list
  *	of ttys that the driver keeps.
- *		FIXME: should we require tty_mutex is held here ??
  *
  */
 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);
-
+	WARN_ON(!mutex_is_locked(&tty_mutex));
 	if (tty->ops->shutdown)
 		tty->ops->shutdown(tty);
 	tty_free_termios(tty);
@@ -1708,6 +1706,9 @@ int tty_release(struct inode *inode, struct file *filp)
 	 * The closing flags are now consistent with the open counts on
 	 * both sides, and we've completed the last operation that could
 	 * block, so it's safe to proceed with closing.
+	 *
+	 * We must *not* drop the tty_mutex until we ensure that a further
+	 * entry into tty_open can not pick up this tty.
 	 */
 	if (pty_master) {
 		if (--o_tty->count < 0) {
@@ -1759,12 +1760,13 @@ int tty_release(struct inode *inode, struct file *filp)
 	}
 
 	mutex_unlock(&tty_mutex);
+	tty_unlock();
+	/* At this point the TTY_CLOSING flag should ensure a dead tty
+	   cannot be re-opened by a racing opener */
 
 	/* check whether both sides are closing ... */
-	if (!tty_closing || (o_tty && !o_tty_closing)) {
-		tty_unlock();
+	if (!tty_closing || (o_tty && !o_tty_closing))
 		return 0;
-	}
 
 #ifdef TTY_DEBUG_HANGUP
 	printk(KERN_DEBUG "%s: freeing tty structure...\n", __func__);
@@ -1777,12 +1779,14 @@ int tty_release(struct inode *inode, struct file *filp)
 	 * The release_tty function takes care of the details of clearing
 	 * the slots and preserving the termios structure.
 	 */
+	mutex_lock(&tty_mutex);
 	release_tty(tty, idx);
+	mutex_unlock(&tty_mutex);
 
 	/* Make this pty number available for reallocation */
 	if (devpts)
 		devpts_kill_index(inode, idx);
-	tty_unlock();
+
 	return 0;
 }
 

trunk/drivers/tty/tty_ldisc.c

@@ -912,7 +912,6 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 	 * race with the set_ldisc code path.
 	 */
 
-	tty_unlock();
 	tty_ldisc_halt(tty);
 	tty_ldisc_flush_works(tty);
 	tty_lock();
@@ -930,6 +929,8 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 	tty_set_termios_ldisc(tty, N_TTY);
 	mutex_unlock(&tty->ldisc_mutex);
 
+	tty_unlock();
+
 	/* This will need doing differently if we need to lock */
 	if (o_tty)
 		tty_ldisc_release(o_tty, NULL);