Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (68 commits)
  U6715 16550A serial driver support
  Char: nozomi, set tty->driver_data appropriately
  Char: nozomi, fix tty->count counting
  serial: max3107: Fix gpiolib support
  hsu: call PCI pm hooks in suspend/resume function
  hsu: some code cleanup
  hsu: add a periodic timer to check dma rx channel
  hsu: driver for Medfield High Speed UART device
  mxser: remove unnesesary NULL check
  serial: add support for OX16PCI958 card
  serial: 68328serial.c: remove dead (ALMA_ANS | DRAGONIXVZ | M68EZ328ADS)
  timbuart: use __devinit and __devexit macros for probe and remove
  serial: MMIO32 support for 8250_early.c
  serial: mcf: don't take spinlocks in already protected functions
  serial: general fixes in the serial_rs485 structure
  serial: fix missing bit coverage of ASYNC_FLAGS
  serial: "altera_uart: simplify altera_uart_console_putc()" checkpatch fixes
  serial: crisv10: formatting of pointers in printk()
  vt: Fix warning: statement with no effect due to vt_kern.h
  tty_io: remove casts from void*
  ...

1 files changed, 47 insertions, 0 deletions

diff --git a/drivers/char/tty_mutex.c b/drivers/char/tty_mutex.c
new file mode 100644
index 000000000000..133697540c73
--- /dev/null
+++ b/drivers/char/tty_mutex.c
@@ -0,0 +1,47 @@
+/*
+ * drivers/char/tty_lock.c
+ */
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#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);
+struct task_struct *__big_tty_mutex_owner;
+EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
+
+/*
+ * Getting the big tty mutex.
+ */
+void __lockfunc tty_lock(void)
+{
+	struct task_struct *task = current;
+
+	WARN_ON(__big_tty_mutex_owner == task);
+
+	mutex_lock(&big_tty_mutex);
+	__big_tty_mutex_owner = task;
+}
+EXPORT_SYMBOL(tty_lock);
+
+void __lockfunc tty_unlock(void)
+{
+	struct task_struct *task = current;
+
+	WARN_ON(__big_tty_mutex_owner != task);
+	__big_tty_mutex_owner = NULL;
+
+	mutex_unlock(&big_tty_mutex);
+}
+EXPORT_SYMBOL(tty_unlock);