From cbcb6d66af4c6169ce1c2d01a3ab345f04b8359d Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Mon, 15 Jun 2009 16:27:29 +0100 Subject: [PATCH] pty: Narrow the race on ldisc locking The pty code has always been buggy on its ldisc handling. The recent changes made the window for the race much bigger. Pending fixing it properly which is not at all trivial, at least make the race small again so we don't disrupt other dev work. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/char/pty.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/char/pty.c b/drivers/char/pty.c index 5acd29e..3910ce1 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -104,7 +104,7 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, struct tty_struct *to = tty->link; int c; - if (!to || tty->stopped) + if (!to || !to->ldisc || tty->stopped) return 0; c = to->receive_room; @@ -148,7 +148,7 @@ static int pty_chars_in_buffer(struct tty_struct *tty) int count; /* We should get the line discipline lock for "tty->link" */ - if (!to || !to->ldisc->ops->chars_in_buffer) + if (!to || !to->ldisc || !to->ldisc->ops->chars_in_buffer) return 0; /* The ldisc must report 0 if no characters available to be read */ @@ -183,7 +183,7 @@ static void pty_flush_buffer(struct tty_struct *tty) struct tty_struct *to = tty->link; unsigned long flags; - if (!to) + if (!to || !to->ldisc) return; if (to->ldisc->ops->flush_buffer) -- 2.7.4