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Commit d7a68be4 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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tty: Only perform flip buffer flush from tty_buffer_flush() 



Now that dropping the buffer lock is not necessary (as result of
converting the spin lock to a mutex), the flip buffer flush no
longer needs to be handled by the buffer work.

Simply signal a flush is required; the buffer work will exit the
i/o loop, which allows tty_buffer_flush() to proceed.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e9975fde

drivers/tty/tty_buffer.c

+21 −42
Original line number Diff line number Diff line
@@ -189,19 +189,11 @@ void tty_buffer_flush(struct tty_struct *tty) 
	struct tty_port *port = tty->port;

	struct tty_bufhead *buf = &port->buf;



	mutex_lock(&buf->flush_mutex);

	/* If the data is being pushed to the tty layer then we can't

	   process it here. Instead set a flag and the flush_to_ldisc

	   path will process the flush request before it exits */

	if (test_bit(TTYP_FLUSHING, &port->iflags)) {

	set_bit(TTYP_FLUSHPENDING, &port->iflags);

		mutex_unlock(&buf->flush_mutex);

		wait_event(tty->read_wait,

				test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0);

		return;

	}



	mutex_lock(&buf->flush_mutex);

	__tty_buffer_flush(port);

	clear_bit(TTYP_FLUSHPENDING, &port->iflags);

	mutex_unlock(&buf->flush_mutex);

}
@@ -429,11 +421,14 @@ static void flush_to_ldisc(struct work_struct *work) 


	mutex_lock(&buf->flush_mutex);



	if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) {

	while (1) {

		struct tty_buffer *head = buf->head;

		int count;



		/* Ldisc or user is trying to flush the buffers. */

		if (test_bit(TTYP_FLUSHPENDING, &port->iflags))

			break;



		count = head->commit - head->read;

		if (!count) {

			if (head->next == NULL)
@@ -443,25 +438,9 @@ static void flush_to_ldisc(struct work_struct *work) 
			continue;

		}



			mutex_unlock(&buf->flush_mutex);



		count = receive_buf(tty, head, count);



			mutex_lock(&buf->flush_mutex);



			/* Ldisc or user is trying to flush the buffers.

			   We may have a deferred request to flush the

			   input buffer, if so pull the chain under the lock

			   and empty the queue */

			if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) {

				__tty_buffer_flush(port);

				clear_bit(TTYP_FLUSHPENDING, &port->iflags);

				wake_up(&tty->read_wait);

		if (!count)

			break;

			} else if (!count)

				break;

		}

		clear_bit(TTYP_FLUSHING, &port->iflags);

	}



	mutex_unlock(&buf->flush_mutex);

include/linux/tty.h

+0 −1
Original line number Diff line number Diff line
@@ -213,7 +213,6 @@ struct tty_port { 
	wait_queue_head_t	delta_msr_wait;	/* Modem status change */

	unsigned long		flags;		/* TTY flags ASY_*/

	unsigned long		iflags;		/* TTYP_ internal flags */

#define TTYP_FLUSHING			1  /* Flushing to ldisc in progress */

#define TTYP_FLUSHPENDING		2  /* Queued buffer flush pending */

	unsigned char		console:1,	/* port is a console */

				low_latency:1;	/* direct buffer flush */