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n_tty: Factor throttle/unthrottle into helper functions 

Prepare for special handling of pty throttle/unthrottle; factor
flow control into helper functions.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2013-06-15 09:14:33 -04:00 committed by Greg Kroah-Hartman
parent 9a4aec2dd5
commit 6367ca72f1
1 changed files with 46 additions and 35 deletions
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81
drivers/tty/n_tty.c
View File

@ -214,6 +214,50 @@ static ssize_t chars_in_buffer(struct tty_struct *tty)
return n;
}
static inline void n_tty_check_throttle(struct tty_struct *tty)
{
/*
* Check the remaining room for the input canonicalization
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
while (1) {
int throttled;
tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
break;
throttled = tty_throttle_safe(tty);
if (!throttled)
break;
}
__tty_set_flow_change(tty, 0);
}
static inline void n_tty_check_unthrottle(struct tty_struct *tty)
{
/* If there is enough space in the read buffer now, let the
* low-level driver know. We use chars_in_buffer() to
* check the buffer, as it now knows about canonical mode.
* Otherwise, if the driver is throttled and the line is
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
* we won't get any more characters.
*/
while (1) {
int unthrottled;
tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
break;
if (!tty->count)
break;
n_tty_set_room(tty);
unthrottled = tty_unthrottle_safe(tty);
if (!unthrottled)
break;
}
__tty_set_flow_change(tty, 0);
}
/**
* put_tty_queue - add character to tty
* @c: character
@ -1508,21 +1552,7 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
wake_up_interruptible(&tty->read_wait);
}
/*
* Check the remaining room for the input canonicalization
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
while (1) {
int throttled;
tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
break;
throttled = tty_throttle_safe(tty);
if (!throttled)
break;
}
__tty_set_flow_change(tty, 0);
n_tty_check_throttle(tty);
}
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
@ -2069,26 +2099,7 @@ do_it_again:
}
}
/* If there is enough space in the read buffer now, let the
* low-level driver know. We use chars_in_buffer() to
* check the buffer, as it now knows about canonical mode.
* Otherwise, if the driver is throttled and the line is
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
* we won't get any more characters.
*/
while (1) {
int unthrottled;
tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
break;
if (!tty->count)
break;
n_tty_set_room(tty);
unthrottled = tty_unthrottle_safe(tty);
if (!unthrottled)
break;
}
__tty_set_flow_change(tty, 0);
n_tty_check_unthrottle(tty);
if (b - buf >= minimum)
break;