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>
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 65c7c62..5505ffc 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -47,7 +47,6 @@
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
- /* Review - krefs on tty_link ?? */
if (!tty->link)
return;
tty->link->packet = 0;
@@ -63,9 +62,9 @@
mutex_unlock(&devpts_mutex);
}
#endif
- tty_unlock(tty);
+ tty_unlock();
tty_vhangup(tty->link);
- tty_lock(tty);
+ tty_lock();
}
}
@@ -623,27 +622,26 @@
return retval;
/* find a device that is not in use. */
- mutex_lock(&devpts_mutex);
+ tty_lock();
index = devpts_new_index(inode);
+ tty_unlock();
if (index < 0) {
retval = index;
goto err_file;
}
- mutex_unlock(&devpts_mutex);
-
mutex_lock(&tty_mutex);
+ mutex_lock(&devpts_mutex);
tty = tty_init_dev(ptm_driver, index);
+ mutex_unlock(&devpts_mutex);
+ tty_lock();
+ mutex_unlock(&tty_mutex);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
goto out;
}
- /* The tty returned here is locked so we can safely
- drop the mutex */
- mutex_unlock(&tty_mutex);
-
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
tty_add_file(tty, filp);
@@ -656,17 +654,16 @@
if (retval)
goto err_release;
- tty_unlock(tty);
+ tty_unlock();
return 0;
err_release:
- tty_unlock(tty);
+ tty_unlock();
tty_release(inode, filp);
return retval;
out:
- mutex_unlock(&tty_mutex);
devpts_kill_index(inode, index);
+ tty_unlock();
err_file:
- mutex_unlock(&devpts_mutex);
tty_free_file(filp);
return retval;
}