From: Alan Cox Date: Thu, 15 Jan 2009 13:30:25 +0000 (+0000) Subject: tty: Fix race in the flush for some ldiscs X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c0253eec2a8e1140dd9672a1efe095cdcf5811d0;p=openwrt%2Fstaging%2Fblogic.git tty: Fix race in the flush for some ldiscs If you issue an ioctl to flush a tty as the line discipline is changing or otherwise unplugged you can get a crash. The bug is very old but the rest of the BKL lock dropping and some very "good" luck on Ingo's part caught an example. Use the correct ldisc_ref form so that we wait for the ldisc change to complete and then flush Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index a408c8e487ec..6f4c7d0a53bf 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -1057,7 +1057,7 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg) if (retval) return retval; - ld = tty_ldisc_ref(tty); + ld = tty_ldisc_ref_wait(tty); switch (arg) { case TCIFLUSH: if (ld && ld->ops->flush_buffer)