tty: Revert the tty locking series, it needs more work

This reverts the tty layer change to use per-tty locking, because it's
not correct yet, and fixing it will require some more deep surgery.

The main revert is d29f3ef39be4 ("tty_lock: Localise the lock"), but
there are several smaller commits that built upon it, they also get
reverted here. The list of reverted commits is:

  fde86d310886 - tty: add lockdep annotations
  8f6576ad476b - tty: fix ldisc lock inversion trace
  d3ca8b64b97e - pty: Fix lock inversion
  b1d679afd766 - tty: drop the pty lock during hangup
  abcefe5fc357 - tty/amiserial: Add missing argument for tty_unlock()
  fd11b42e3598 - cris: fix missing tty arg in wait_event_interruptible_tty call
  d29f3ef39be4 - tty_lock: Localise the lock

The revert had a trivial conflict in the 68360serial.c staging driver
that got removed in the meantime.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 14 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 4990ef2b1fb7..9f47ab540f65 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -268,7 +268,6 @@ struct tty_struct {
         struct mutex ldisc_mutex;
         struct tty_ldisc *ldisc;
 
-        struct mutex legacy_mutex;
         struct mutex termios_mutex;
         spinlock_t ctrl_lock;
         /* Termios values are protected by the termios mutex */
@@ -606,12 +605,8 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
 
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
-extern void __lockfunc tty_lock(struct tty_struct *tty);
-extern void __lockfunc tty_unlock(struct tty_struct *tty);
-extern void __lockfunc tty_lock_pair(struct tty_struct *tty,
-                                struct tty_struct *tty2);
-extern void __lockfunc tty_unlock_pair(struct tty_struct *tty,
-                                struct tty_struct *tty2);
+extern void __lockfunc tty_lock(void) __acquires(tty_lock);
+extern void __lockfunc tty_unlock(void) __releases(tty_lock);
 
 /*
  * this shall be called only from where BTM is held (like close)
@@ -626,9 +621,9 @@ extern void __lockfunc tty_unlock_pair(struct tty_struct *tty,
 static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
                 long timeout)
 {
-        tty_unlock(tty); /* tty->ops->close holds the BTM, drop it while waiting */
+        tty_unlock(); /* tty->ops->close holds the BTM, drop it while waiting */
         tty_wait_until_sent(tty, timeout);
-        tty_lock(tty);
+        tty_lock();
 }
 
 /*
@@ -643,16 +638,16 @@ static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
  *
  * Do not use in new code.
  */
-#define wait_event_interruptible_tty(tty, wq, condition)                \
+#define wait_event_interruptible_tty(wq, condition)                     \
 ({                                                                      \
         int __ret = 0;                                                  \
         if (!(condition)) {                                             \
-                __wait_event_interruptible_tty(tty, wq, condition, __ret);      \
+                __wait_event_interruptible_tty(wq, condition, __ret);   \
         }                                                               \
         __ret;                                                          \
 })
 
-#define __wait_event_interruptible_tty(tty, wq, condition, ret)         \
+#define __wait_event_interruptible_tty(wq, condition, ret)              \
 do {                                                                    \
         DEFINE_WAIT(__wait);                                            \
                                                                         \
@@ -661,9 +656,9 @@ do {									\
                 if (condition)                                          \
                         break;                                          \
                 if (!signal_pending(current)) {                         \
-                        tty_unlock(tty);                                        \
+                        tty_unlock();                                   \
                         schedule();                                     \
-                        tty_lock(tty);                                  \
+                        tty_lock();                                     \
                         continue;                                       \
                 }                                                       \
                 ret = -ERESTARTSYS;                                     \