tty: Add driver unthrottle in ioctl(...,TCFLSH,..).

Regression 'tty: fix "IRQ45: nobody cared"' Regression commit 7b292b4 Function reset_buffer_flags() also invoked during the ioctl(...,TCFLSH,..). At the time of request we can have full buffers and throttled driver too. If we don't unthrottle driver, we can get forever throttled driver, because, after request, we will have empty buffers and throttled driver and there is no place to unthrottle driver. It simple reproduce with "pty" pair then one side sleep on tty->write_wait, and other side do ioctl(...,TCFLSH,..). Then there is no place to do writers wake up. Signed-off-by: Ilya Zykov <[email protected]> Cc: Alan Cox <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
kishon · Jan 19, 2013 · a1bf958 · a1bf958
1 parent 33aeb9d
commit a1bf958
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
@@ -1096,12 +1096,16 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
 	ld = tty_ldisc_ref_wait(tty);
 	switch (arg) {
 	case TCIFLUSH:
-		if (ld && ld->ops->flush_buffer)
+		if (ld && ld->ops->flush_buffer) {
 			ld->ops->flush_buffer(tty);
+			tty_unthrottle(tty);
+		}
 		break;
 	case TCIOFLUSH:
-		if (ld && ld->ops->flush_buffer)
+		if (ld && ld->ops->flush_buffer) {
 			ld->ops->flush_buffer(tty);
+			tty_unthrottle(tty);
+		}
 		/* fall through */
 	case TCOFLUSH:
 		tty_driver_flush_buffer(tty);