X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=drivers%2Ftty%2Ftty_ldisc.c;h=49001fa2ea2f0084480c2d09ba4c1cd325b12851;hb=3ff51a199f9e85aed843471bc10dae9e94dbb0fc;hp=2d822aa259b2f73ad93212c949e900701d776f04;hpb=595bf999e3a864f40e049c67c42ecee50fb7a78a;p=deliverable%2Flinux.git

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 2d822aa259b2..49001fa2ea2f 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -523,9 +523,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (IS_ERR(new_ldisc))
 		return PTR_ERR(new_ldisc);
 
+	tty_lock(tty);
 	retval = tty_ldisc_lock_pair_timeout(tty, o_tty, 5 * HZ);
 	if (retval) {
 		tty_ldisc_put(new_ldisc);
+		tty_unlock(tty);
 		return retval;
 	}
 
@@ -536,14 +538,13 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (tty->ldisc->ops->num == ldisc) {
 		tty_ldisc_enable_pair(tty, o_tty);
 		tty_ldisc_put(new_ldisc);
+		tty_unlock(tty);
 		return 0;
 	}
 
 	old_ldisc = tty->ldisc;
-	tty_lock(tty);
 
-	if (test_bit(TTY_HUPPING, &tty->flags) ||
-	    test_bit(TTY_HUPPED, &tty->flags)) {
+	if (test_bit(TTY_HUPPED, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
 		tty_ldisc_enable_pair(tty, o_tty);
@@ -675,8 +676,6 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 	wake_up_interruptible_poll(&tty->read_wait, POLLIN);
 
-	tty_unlock(tty);
-
 	/*
 	 * Shutdown the current line discipline, and reset it to
 	 * N_TTY if need be.
@@ -684,7 +683,6 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	 * Avoid racing set_ldisc or tty_ldisc_release
 	 */
 	tty_ldisc_lock_pair(tty, tty->link);
-	tty_lock(tty);
 
 	if (tty->ldisc) {
 
@@ -764,6 +762,8 @@ static void tty_ldisc_kill(struct tty_struct *tty)
  *	Called during the final close of a tty/pty pair in order to shut down
  *	the line discpline layer. On exit the ldisc assigned is N_TTY and the
  *	ldisc has not been opened.
+ *
+ *	Holding ldisc_sem write lock serializes tty->ldisc changes.
  */
 
 void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
@@ -776,13 +776,9 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 	tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc);
 
 	tty_ldisc_lock_pair(tty, o_tty);
-	tty_lock_pair(tty, o_tty);
-
 	tty_ldisc_kill(tty);
 	if (o_tty)
 		tty_ldisc_kill(o_tty);
-
-	tty_unlock_pair(tty, o_tty);
 	tty_ldisc_unlock_pair(tty, o_tty);
 
 	/* And the memory resources remaining (buffers, termios) will be