Patch "xtensa: ISS: don't hang if stdin EOF is reached" has been added to the 4.4-stable tree

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

xtensa: ISS: don't hang if stdin EOF is reached

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xtensa-iss-don-t-hang-if-stdin-eof-is-reached.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Max Filippov <[email protected]>
Date: Tue, 9 Feb 2016 01:02:38 +0300
Subject: xtensa: ISS: don't hang if stdin EOF is reached

From: Max Filippov <[email protected]>

commit 362014c8d9d51d504c167c44ac280169457732be upstream.

Simulator stdin may be connected to a file, when its end is reached kernel hangs in infinite loop inside rs_poll, because simc_poll always signals that descriptor 0 is readable and simc_read always returns 0. Check simc_read return value and exit loop if it's not positive. Also don't rewind polling timer if it's zero.

---
 arch/xtensa/platforms/iss/console.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

@@ -100,21 +100,23 @@ static void rs_poll(unsigned long priv)
 {
 	struct tty_port *port = (struct tty_port *)priv;
 	int i = 0;
+	int rd = 1;
 	unsigned char c;
 
 	spin_lock(&timer_lock);
 
 	while (simc_poll(0)) {
-		simc_read(0, &c, 1);
+		rd = simc_read(0, &c, 1);
+		if (rd <= 0)
+			break;
 		tty_insert_flip_char(port, c, TTY_NORMAL);
 		i++;
 	}
 
 	if (i)
 		tty_flip_buffer_push(port);
-
-
-	mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
+	if (rd)
+		mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
 	spin_unlock(&timer_lock);
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/xtensa-iss-don-t-hang-if-stdin-eof-is-reached.patch queue-4.4/xtensa-clear-all-dbreakc-registers-on-start.patch queue-4.4/xtensa-fix-preemption-in-clear-copy-_user_highpage.patch