patch "tty: Handle problem if line discipline does not have receive_buf" added to tty-linus

This is a note to let you know that I've just added the patch titled

tty: Handle problem if line discipline does not have receive_buf

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 27cfb3a53be46a54ec5e0bd04e51995b74c90343 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <[email protected]>
Date: Sun, 20 Jan 2019 10:46:58 +0100
Subject: tty: Handle problem if line discipline does not have receive_buf

Some tty line disciplines do not have a receive buf callback, so properly check for that before calling it. If they do not have this callback, just eat the character quietly, as we can't fail this call.

---
 drivers/tty/tty_io.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 23c6fd238422..21ffcce16927 100644
@@ -2189,7 +2189,8 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
 	ld = tty_ldisc_ref_wait(tty);
 	if (!ld)
 		return -EIO;
-	ld->ops->receive_buf(tty, &ch, &mbz, 1);
+	if (ld->ops->receive_buf)
+		ld->ops->receive_buf(tty, &ch, &mbz, 1);
 	tty_ldisc_deref(ld);
 	return 0;
 }

2.20.1