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TTY: fix tty_wait_until_sent maximum timeout 

Currently tty_wait_until_sent may take up to twice as long as the
requested timeout while waiting for driver and hardware buffers to
drain.

Fix this by taking the remaining number of jiffies after waiting for
driver buffers to drain into account so that the timeout actually
becomes a maximum timeout as it is documented to be.

Note that this specifically implies tighter timings when closing a port
as a consequence of actually honouring the port closing-wait setting
for drivers relying on tty_wait_until_sent_from_close (e.g. via
tty_port_close_start).

Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2015-03-04 10:39:07 +01:00 committed by Greg Kroah-Hartman
parent 79fbf4a550
commit c37bc682e3
1 changed files with 3 additions and 3 deletions
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6
drivers/tty/tty_ioctl.c
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@ -218,10 +218,10 @@ 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_chars_in_buffer(tty), timeout) < 0) {
timeout = wait_event_interruptible_timeout(tty->write_wait,
!tty_chars_in_buffer(tty), timeout);
if (timeout <= 0)
return;
}
if (timeout == MAX_SCHEDULE_TIMEOUT)
timeout = 0;