[PATCH 3.12 119/212] n_tty: Ensure reader restarts worker for next reader

[Greg Kroah-Hartman]

3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>

commit 42458f41d08f0873299e830464c1232a6839297d upstream.

A departing reader must restart a flush_to_ldisc() worker _before_
the next reader enters the read loop; this is to avoid the new reader
concluding no more i/o is available and prematurely exiting, when the
old reader simply hasn't re-started the worker yet.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/tty/n_tty.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2253,6 +2253,9 @@ static ssize_t n_tty_read(struct tty_str
 		if (time)
 			timeout = time;
 	}
+	n_tty_set_room(tty);
+	up_read(&tty->termios_rwsem);
+
 	mutex_unlock(&ldata->atomic_read_lock);
 	remove_wait_queue(&tty->read_wait, &wait);
 
@@ -2263,8 +2266,6 @@ static ssize_t n_tty_read(struct tty_str
 	if (b - buf)
 		retval = b - buf;
 
-	n_tty_set_room(tty);
-	up_read(&tty->termios_rwsem);
 	return retval;
 }
 


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