Merge tag 'tty-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver updates from Greg KH:
 "Here's the big tty/serial driver update for 3.19-rc1.

  There are a number of TTY core changes/fixes in here from Peter Hurley
  that have all been teted in linux-next for a long time now.  There are
  also the normal serial driver updates as well, full details in the
  changelog below"

* tag 'tty-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (219 commits)
  serial: pxa: hold port.lock when reporting modem line changes
  tty-hvsi_lib: Deletion of an unnecessary check before the function call "tty_kref_put"
  tty: Deletion of unnecessary checks before two function calls
  n_tty: Fix read_buf race condition, increment read_head after pushing data
  serial: of-serial: add PM suspend/resume support
  Revert "serial: of-serial: add PM suspend/resume support"
  Revert "serial: of-serial: fix up PM ops on no_console_suspend and port type"
  serial: 8250: don't attempt a trylock if in sysrq
  serial: core: Add big-endian iotype
  serial: samsung: use port->fifosize instead of hardcoded values
  serial: samsung: prefer to use fifosize from driver data
  serial: samsung: fix style problems
  serial: samsung: wait for transfer completion before clock disable
  serial: icom: fix error return code
  serial: tegra: clean up tty-flag assignments
  serial: Fix io address assign flow with Fintek PCI-to-UART Product
  serial: mxs-auart: fix tx_empty against shift register
  serial: mxs-auart: fix gpio change detection on interrupt
  serial: mxs-auart: Fix mxs_auart_set_ldisc()
  serial: 8250_dw: Use 64-bit access for OCTEON.
  ...

1 files changed, 21 insertions, 28 deletions

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 2e41abebbcba..4486741190c4 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -4,19 +4,23 @@
 #include <linux/semaphore.h>
 #include <linux/sched.h>
 
+/*
+ * Nested tty locks are necessary for releasing pty pairs.
+ * The stable lock order is master pty first, then slave pty.
+ */
+
 /* Legacy tty mutex glue */
 
 enum {
 	TTY_MUTEX_NORMAL,
-	TTY_MUTEX_NESTED,
+	TTY_MUTEX_SLAVE,
 };
 
 /*
  * Getting the big tty mutex.
  */
 
-static void __lockfunc tty_lock_nested(struct tty_struct *tty,
-				       unsigned int subclass)
+void __lockfunc tty_lock(struct tty_struct *tty)
 {
 	if (tty->magic != TTY_MAGIC) {
 		pr_err("L Bad %p\n", tty);
@@ -24,12 +28,7 @@ static void __lockfunc tty_lock_nested(struct tty_struct *tty,
 		return;
 	}
 	tty_kref_get(tty);
-	mutex_lock_nested(&tty->legacy_mutex, subclass);
-}
-
-void __lockfunc tty_lock(struct tty_struct *tty)
-{
-	return tty_lock_nested(tty, TTY_MUTEX_NORMAL);
+	mutex_lock(&tty->legacy_mutex);
 }
 EXPORT_SYMBOL(tty_lock);
 
@@ -45,29 +44,23 @@ void __lockfunc tty_unlock(struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_unlock);
 
-/*
- * Getting the big tty mutex for a pair of ttys with lock ordering
- * On a non pty/tty pair tty2 can be NULL which is just fine.
- */
-void __lockfunc tty_lock_pair(struct tty_struct *tty,
-					struct tty_struct *tty2)
+void __lockfunc tty_lock_slave(struct tty_struct *tty)
 {
-	if (tty < tty2) {
+	if (tty && tty != tty->link) {
+		WARN_ON(!mutex_is_locked(&tty->link->legacy_mutex) ||
+			!tty->driver->type == TTY_DRIVER_TYPE_PTY ||
+			!tty->driver->type == PTY_TYPE_SLAVE);
 		tty_lock(tty);
-		tty_lock_nested(tty2, TTY_MUTEX_NESTED);
-	} else {
-		if (tty2 && tty2 != tty)
-			tty_lock(tty2);
-		tty_lock_nested(tty, TTY_MUTEX_NESTED);
 	}
 }
-EXPORT_SYMBOL(tty_lock_pair);
 
-void __lockfunc tty_unlock_pair(struct tty_struct *tty,
-						struct tty_struct *tty2)
+void __lockfunc tty_unlock_slave(struct tty_struct *tty)
+{
+	if (tty && tty != tty->link)
+		tty_unlock(tty);
+}
+
+void tty_set_lock_subclass(struct tty_struct *tty)
 {
-	tty_unlock(tty);
-	if (tty2 && tty2 != tty)
-		tty_unlock(tty2);
+	lockdep_set_subclass(&tty->legacy_mutex, TTY_MUTEX_SLAVE);
 }
-EXPORT_SYMBOL(tty_unlock_pair);