From: Cory T. Tusar Date: Sun, 23 Dec 2007 20:34:51 +0000 (-0800) Subject: tty: fix logic change introduced by wait_event_interruptible_timeout() X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=db99247ac68fc352100090ad7704fb5efb9327b6;p=openwrt%2Fstaging%2Fblogic.git tty: fix logic change introduced by wait_event_interruptible_timeout() Commit 5a52bd4a2dcb570333ce6fe2e16cd311650dbdc8 introduced a subtle logic change in tty_wait_until_sent(). The original version would only error out of the 'do { ... } while (timeout)' loop if signal_pending() evaluated to true; a timeout or break due to an empty buffer would fall out of the loop and into the tty->driver->wait_until_sent handling. The current implementation will error out on either a pending signal or an empty buffer, falling through to the tty->driver->wait_until_sent handling only on a timeout. The ->wait_until_sent() will not be reached if the buffer empties before timeout jiffies have elapsed. This behavior differs from that prior to commit 5a52bd4a2dcb570333ce6fe2e16cd311650dbdc8. I turned this up while using a little serial download utility to bootstrap an ARM-based eval board. The util worked fine on 2.6.22.x, but consistently failed on 2.6.23.x. Once I'd determined that, I narrowed things down with git bisect, and found the above difference in logic in tty_wait_until_sent() by inspection. This change reverts the logic flow in tty_wait_until_sent() to match that prior to the aforementioned commit. Signed-off-by: Cory T. Tusar Cc: Alan Cox Acked-by: Jiri Slaby Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index 1bdd2bf4f37d..e02d59245a17 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -62,7 +62,7 @@ void tty_wait_until_sent(struct tty_struct * tty, long timeout) if (!timeout) timeout = MAX_SCHEDULE_TIMEOUT; if (wait_event_interruptible_timeout(tty->write_wait, - !tty->driver->chars_in_buffer(tty), timeout)) + !tty->driver->chars_in_buffer(tty), timeout) < 0) return; if (tty->driver->wait_until_sent) tty->driver->wait_until_sent(tty, timeout);