tty: fix logic change introduced by wait_event_interruptible_timeout()
Commit5a52bd4a2d
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 commit5a52bd4a2d
. 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 <ctusar@videon-central.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Acked-by: Jiri Slaby <jirislaby@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -62,7 +62,7 @@ void tty_wait_until_sent(struct tty_struct * tty, long timeout)
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if (!timeout)
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timeout = MAX_SCHEDULE_TIMEOUT;
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if (wait_event_interruptible_timeout(tty->write_wait,
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!tty->driver->chars_in_buffer(tty), timeout))
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!tty->driver->chars_in_buffer(tty), timeout) < 0)
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return;
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if (tty->driver->wait_until_sent)
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tty->driver->wait_until_sent(tty, timeout);
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