Merge tag 'tty-3.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull TTY updates from Greg Kroah-Hartman:
 "Here's the big TTY/serial driver pull request for the 3.5-rc1 merge
  window.

  Nothing major in here, just lots of incremental changes from Alan and
  Jiri reworking some tty core things to behave better and to get a more
  solid grasp on some of the nasty tty locking issues.

  There are a few tty and serial driver updates in here as well.

  All of this has been in the linux-next releases for a while with no
  problems.

  Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"

* tag 'tty-3.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (115 commits)
  serial: bfin_uart: Make MMR access compatible with 32 bits bf609 style controller.
  serial: bfin_uart: RTS and CTS MMRs can be either 16-bit width or 32-bit width.
  serial: bfin_uart: narrow the reboot condition in DMA tx interrupt
  serial: bfin_uart: Adapt bf5xx serial driver to bf60x serial4 controller.
  Revert "serial_core: Update buffer overrun statistics."
  tty: hvc_xen: NULL dereference on allocation failure
  tty: Fix LED error return
  tty: Allow uart_register/unregister/register
  tty: move global ldisc idle waitqueue to the individual ldisc
  serial8250-em: Add DT support
  serial8250-em: clk_get() IS_ERR() error handling fix
  serial_core: Update buffer overrun statistics.
  tty: drop the pty lock during hangup
  cris: fix missing tty arg in wait_event_interruptible_tty call
  tty/amiserial: Add missing argument for tty_unlock()
  tty_lock: Localise the lock
  pty: Lock the devpts bits privately
  tty_lock: undo the old tty_lock use on the ctty
  serial8250-em: Emma Mobile UART driver V2
  Add missing call to uart_update_timeout()
  ...

1 files changed, 45 insertions, 15 deletions

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 9ff986c32a21..69adc80c98cd 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -4,29 +4,59 @@
 #include <linux/semaphore.h>
 #include <linux/sched.h>
 
-/*
- * The 'big tty mutex'
- *
- * This mutex is taken and released by tty_lock() and tty_unlock(),
- * replacing the older big kernel lock.
- * It can no longer be taken recursively, and does not get
- * released implicitly while sleeping.
- *
- * Don't use in new code.
- */
-static DEFINE_MUTEX(big_tty_mutex);
+/* Legacy tty mutex glue */
 
 /*
  * Getting the big tty mutex.
  */
-void __lockfunc tty_lock(void)
+
+void __lockfunc tty_lock(struct tty_struct *tty)
 {
-	mutex_lock(&big_tty_mutex);
+	if (tty->magic != TTY_MAGIC) {
+		printk(KERN_ERR "L Bad %p\n", tty);
+		WARN_ON(1);
+		return;
+	}
+	tty_kref_get(tty);
+	mutex_lock(&tty->legacy_mutex);
 }
 EXPORT_SYMBOL(tty_lock);
 
-void __lockfunc tty_unlock(void)
+void __lockfunc tty_unlock(struct tty_struct *tty)
 {
-	mutex_unlock(&big_tty_mutex);
+	if (tty->magic != TTY_MAGIC) {
+		printk(KERN_ERR "U Bad %p\n", tty);
+		WARN_ON(1);
+		return;
+	}
+	mutex_unlock(&tty->legacy_mutex);
+	tty_kref_put(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)
+{
+	if (tty < tty2) {
+		tty_lock(tty);
+		tty_lock(tty2);
+	} else {
+		if (tty2 && tty2 != tty)
+			tty_lock(tty2);
+		tty_lock(tty);
+	}
+}
+EXPORT_SYMBOL(tty_lock_pair);
+
+void __lockfunc tty_unlock_pair(struct tty_struct *tty,
+						struct tty_struct *tty2)
+{
+	tty_unlock(tty);
+	if (tty2 && tty2 != tty)
+		tty_unlock(tty2);
+}
+EXPORT_SYMBOL(tty_unlock_pair);