Merge tag 'tty-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull TTY changes from Greg Kroah-Hartman:
 "As we skipped the merge window for 3.6-rc1 for the tty tree,
  everything is now settled down and working properly, so we are ready
  for 3.7-rc1.  Here's the patchset, it's big, but the large changes are
  removing a firmware file and adding a staging tty driver (it depended
  on the tty core changes, so it's going through this tree instead of
  the staging tree.)

  All of these patches have been in the linux-next tree for a while.

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

Fix up more-or-less trivial conflicts in
 - drivers/char/pcmcia/synclink_cs.c:
    tty NULL dereference fix vs tty_port_cts_enabled() helper function
 - drivers/staging/{Kconfig,Makefile}:
    add-add conflict (dgrp driver added close to other staging drivers)
 - drivers/staging/ipack/devices/ipoctal.c:
    "split ipoctal_channel from iopctal" vs "TTY: use tty_port_register_device"

* tag 'tty-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (235 commits)
  tty/serial: Add kgdb_nmi driver
  tty/serial/amba-pl011: Quiesce interrupts in poll_get_char
  tty/serial/amba-pl011: Implement poll_init callback
  tty/serial/core: Introduce poll_init callback
  kdb: Turn KGDB_KDB=n stubs into static inlines
  kdb: Implement disable_nmi command
  kernel/debug: Mask KGDB NMI upon entry
  serial: pl011: handle corruption at high clock speeds
  serial: sccnxp: Make 'default' choice in switch last
  serial: sccnxp: Remove mask termios caps for SW flow control
  serial: sccnxp: Report actual baudrate back to core
  serial: samsung: Add poll_get_char & poll_put_char
  Powerpc 8xx CPM_UART setting MAXIDL register proportionaly to baud rate
  Powerpc 8xx CPM_UART maxidl should not depend on fifo size
  Powerpc 8xx CPM_UART too many interrupts
  Powerpc 8xx CPM_UART desynchronisation
  serial: set correct baud_base for EXSYS EX-41092 Dual 16950
  serial: omap: fix the reciever line error case
  8250: blacklist Winbond CIR port
  8250_pnp: do pnp probe before legacy probe
  ...

1 files changed, 56 insertions, 15 deletions

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 9ff986c32a21..67feac9e6ebb 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -4,29 +4,70 @@
 #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 */
+
+enum {
+	TTY_MUTEX_NORMAL,
+	TTY_MUTEX_NESTED,
+};
 
 /*
  * Getting the big tty mutex.
  */
-void __lockfunc tty_lock(void)
+
+static void __lockfunc tty_lock_nested(struct tty_struct *tty,
+				       unsigned int subclass)
 {
-	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_nested(&tty->legacy_mutex, subclass);
+}
+
+void __lockfunc tty_lock(struct tty_struct *tty)
+{
+	return tty_lock_nested(tty, TTY_MUTEX_NORMAL);
 }
 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_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)
+{
+	tty_unlock(tty);
+	if (tty2 && tty2 != tty)
+		tty_unlock(tty2);
+}
+EXPORT_SYMBOL(tty_unlock_pair);