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Commit c5c34d48 authored by Paul Fulghum's avatar Paul Fulghum Committed by Linus Torvalds
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tty: flush flip buffer on ldisc input queue flush 



Flush the tty flip buffer when the line discipline input queue is flushed,
including the user call tcflush(TCIFLUSH/TCIOFLUSH).  This prevents
unexpected stale data after a user application calls tcflush().

Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Cc: Antonino Ingargiola <tritemio@gmail.com>
Signed-off-by: default avatarPaul Fulghum <paulkf@microgate.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e3bf460f

drivers/char/tty_io.c

+33 −0
Original line number Diff line number Diff line
@@ -368,6 +368,29 @@ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b) 
	}

}



/**

 *	tty_buffer_flush		-	flush full tty buffers

 *	@tty: tty to flush

 *

 *	flush all the buffers containing receive data

 *

 *	Locking: none

 */



static void tty_buffer_flush(struct tty_struct *tty)

{

	struct tty_buffer *thead;

	unsigned long flags;



	spin_lock_irqsave(&tty->buf.lock, flags);

	while((thead = tty->buf.head) != NULL) {

		tty->buf.head = thead->next;

		tty_buffer_free(tty, thead);

	}

	tty->buf.tail = NULL;

	spin_unlock_irqrestore(&tty->buf.lock, flags);

}



/**

 *	tty_buffer_find		-	find a free tty buffer

 *	@tty: tty owning the buffer
@@ -1248,6 +1271,7 @@ void tty_ldisc_flush(struct tty_struct *tty) 
			ld->flush_buffer(tty);

		tty_ldisc_deref(ld);

	}

	tty_buffer_flush(tty);

}



EXPORT_SYMBOL_GPL(tty_ldisc_flush);
@@ -3350,6 +3374,15 @@ int tty_ioctl(struct inode * inode, struct file * file, 
		case TIOCMBIC:

		case TIOCMBIS:

			return tty_tiocmset(tty, file, cmd, p);

		case TCFLSH:

			switch (arg) {

			case TCIFLUSH:

			case TCIOFLUSH:

				/* flush tty buffer and allow ldisc to process ioctl */

				tty_buffer_flush(tty);

				break;

			}

			break;

	}

	if (tty->driver->ioctl) {

		retval = (tty->driver->ioctl)(tty, file, cmd, arg);