tty: revert incorrectly applied lock patch
I sent GregKH this after the pre-requisites. He dropped the pre-requesites
for good reason and unfortunately then applied this patch. Without this
reverted you get random kernel memory corruption which will make bisecting
anything between it and the properly applied patches a complete sod.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 847f7ed..6f99c99 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -568,7 +568,7 @@
if (IS_ERR(new_ldisc))
return PTR_ERR(new_ldisc);
- tty_lock(tty);
+ tty_lock();
/*
* We need to look at the tty locking here for pty/tty pairs
* when both sides try to change in parallel.
@@ -582,12 +582,12 @@
*/
if (tty->ldisc->ops->num == ldisc) {
- tty_unlock(tty);
+ tty_unlock();
tty_ldisc_put(new_ldisc);
return 0;
}
- tty_unlock(tty);
+ tty_unlock();
/*
* Problem: What do we do if this blocks ?
* We could deadlock here
@@ -595,7 +595,7 @@
tty_wait_until_sent(tty, 0);
- tty_lock(tty);
+ tty_lock();
mutex_lock(&tty->ldisc_mutex);
/*
@@ -605,10 +605,10 @@
while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) {
mutex_unlock(&tty->ldisc_mutex);
- tty_unlock(tty);
+ tty_unlock();
wait_event(tty_ldisc_wait,
test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
- tty_lock(tty);
+ tty_lock();
mutex_lock(&tty->ldisc_mutex);
}
@@ -623,7 +623,7 @@
o_ldisc = tty->ldisc;
- tty_unlock(tty);
+ tty_unlock();
/*
* Make sure we don't change while someone holds a
* reference to the line discipline. The TTY_LDISC bit
@@ -650,7 +650,7 @@
retval = tty_ldisc_wait_idle(tty, 5 * HZ);
- tty_lock(tty);
+ tty_lock();
mutex_lock(&tty->ldisc_mutex);
/* handle wait idle failure locked */
@@ -665,7 +665,7 @@
clear_bit(TTY_LDISC_CHANGING, &tty->flags);
mutex_unlock(&tty->ldisc_mutex);
tty_ldisc_put(new_ldisc);
- tty_unlock(tty);
+ tty_unlock();
return -EIO;
}
@@ -708,7 +708,7 @@
if (o_work)
schedule_work(&o_tty->buf.work);
mutex_unlock(&tty->ldisc_mutex);
- tty_unlock(tty);
+ tty_unlock();
return retval;
}
@@ -816,11 +816,11 @@
* need to wait for another function taking the BTM
*/
clear_bit(TTY_LDISC, &tty->flags);
- tty_unlock(tty);
+ tty_unlock();
cancel_work_sync(&tty->buf.work);
mutex_unlock(&tty->ldisc_mutex);
retry:
- tty_lock(tty);
+ tty_lock();
mutex_lock(&tty->ldisc_mutex);
/* At this point we have a closed ldisc and we want to
@@ -831,7 +831,7 @@
if (atomic_read(&tty->ldisc->users) != 1) {
char cur_n[TASK_COMM_LEN], tty_n[64];
long timeout = 3 * HZ;
- tty_unlock(tty);
+ tty_unlock();
while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
timeout = MAX_SCHEDULE_TIMEOUT;
@@ -894,23 +894,6 @@
tty_ldisc_enable(tty);
return 0;
}
-
-static void tty_ldisc_kill(struct tty_struct *tty)
-{
- mutex_lock(&tty->ldisc_mutex);
- /*
- * Now kill off the ldisc
- */
- tty_ldisc_close(tty, tty->ldisc);
- tty_ldisc_put(tty->ldisc);
- /* Force an oops if we mess this up */
- tty->ldisc = NULL;
-
- /* Ensure the next open requests the N_TTY ldisc */
- tty_set_termios_ldisc(tty, N_TTY);
- mutex_unlock(&tty->ldisc_mutex);
-}
-
/**
* tty_ldisc_release - release line discipline
* @tty: tty being shut down
@@ -929,19 +912,27 @@
* race with the set_ldisc code path.
*/
- tty_unlock_pair(tty, o_tty);
+ tty_unlock();
tty_ldisc_halt(tty);
tty_ldisc_flush_works(tty);
- if (o_tty) {
- tty_ldisc_halt(o_tty);
- tty_ldisc_flush_works(o_tty);
- }
- tty_lock_pair(tty, o_tty);
+ tty_lock();
+ mutex_lock(&tty->ldisc_mutex);
+ /*
+ * Now kill off the ldisc
+ */
+ tty_ldisc_close(tty, tty->ldisc);
+ tty_ldisc_put(tty->ldisc);
+ /* Force an oops if we mess this up */
+ tty->ldisc = NULL;
- tty_ldisc_kill(tty);
+ /* Ensure the next open requests the N_TTY ldisc */
+ tty_set_termios_ldisc(tty, N_TTY);
+ mutex_unlock(&tty->ldisc_mutex);
+
+ /* This will need doing differently if we need to lock */
if (o_tty)
- tty_ldisc_kill(o_tty);
+ tty_ldisc_release(o_tty, NULL);
/* And the memory resources remaining (buffers, termios) will be
disposed of when the kref hits zero */