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Commit 6367ca72 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9a4aec2d

drivers/tty/n_tty.c

+46 −35
Original line number Diff line number Diff line
@@ -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 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, 
			}

		}



		/* 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;