From c72f527c104cae8e767e714574238b5550879e0c Mon Sep 17 00:00:00 2001
From: Paul Fulghum <paulkf@microgate.com>
Date: Tue, 22 Jul 2008 11:21:19 +0100
Subject: [PATCH] n_hdlc: honor O_NONBLOCK on write

Make n_hdlc line discipline honor the O_NONBLOCK file flag on write.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/char/n_hdlc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c
index ed4e033..69ec639 100644
--- a/drivers/char/n_hdlc.c
+++ b/drivers/char/n_hdlc.c
@@ -677,6 +677,10 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
 	/* Allocate transmit buffer */
 	/* sleep until transmit buffer available */		
 	while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) {
+		if (file->f_flags & O_NONBLOCK) {
+			error = -EAGAIN;
+			break;
+		}
 		schedule();
 			
 		n_hdlc = tty2n_hdlc (tty);
-- 
2.7.4