1 files changed, 13 insertions, 16 deletions

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 050f4d650891..fb7329ab2b37 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -176,12 +176,11 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 			return ERR_CAST(ldops);
 	}
 
-	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL);
-	if (ld == NULL) {
-		put_ldops(ldops);
-		return ERR_PTR(-ENOMEM);
-	}
-
+	/*
+	 * There is no way to handle allocation failure of only 16 bytes.
+	 * Let's simplify error handling and save more memory.
+	 */
+	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL);
 	ld->ops = ldops;
 	ld->tty = tty;
 
@@ -527,19 +526,16 @@ static int tty_ldisc_failto(struct tty_struct *tty, int ld)
 static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
 {
 	/* There is an outstanding reference here so this is safe */
-	old = tty_ldisc_get(tty, old->ops->num);
-	WARN_ON(IS_ERR(old));
-	tty->ldisc = old;
-	tty_set_termios_ldisc(tty, old->ops->num);
-	if (tty_ldisc_open(tty, old) < 0) {
-		tty_ldisc_put(old);
+	if (tty_ldisc_failto(tty, old->ops->num) < 0) {
+		const char *name = tty_name(tty);
+
+		pr_warn("Falling back ldisc for %s.\n", name);
 		/* The traditional behaviour is to fall back to N_TTY, we
 		   want to avoid falling back to N_NULL unless we have no
 		   choice to avoid the risk of breaking anything */
 		if (tty_ldisc_failto(tty, N_TTY) < 0 &&
 		    tty_ldisc_failto(tty, N_NULL) < 0)
-			panic("Couldn't open N_NULL ldisc for %s.",
-			      tty_name(tty));
+			panic("Couldn't open N_NULL ldisc for %s.", name);
 	}
 }
 
@@ -824,12 +820,13 @@ EXPORT_SYMBOL_GPL(tty_ldisc_release);
  *	the tty structure is not completely set up when this call is made.
  */
 
-void tty_ldisc_init(struct tty_struct *tty)
+int tty_ldisc_init(struct tty_struct *tty)
 {
 	struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY);
 	if (IS_ERR(ld))
-		panic("n_tty: init_tty");
+		return PTR_ERR(ld);
 	tty->ldisc = ld;
+	return 0;
 }
 
 /**