Commit 7ee00fdb authored Oct 18, 2012 by Jiri Slaby Committed by Greg Kroah-Hartman Oct 22, 2012

TTY: vt, fix paste_selection ldisc handling



There used to be a single tty_ldisc_ref_wait. But then, when a
big-tty-mutex (BTM) was introduced, it has to be tty_ldisc_ref +
tty_unlock + tty_ldisc_ref_wait + tty_lock. Later, BTM was removed
from that path and tty_ldisc_ref + tty_ldisc_ref_wait remained there.
But it makes no sense now. So leave there only tty_ldisc_ref_wait.

And when we have a reference to an ldisc, actually use it in the loop.
Otherwise it may be racy.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent fa2ecfc5

drivers/tty/vt/selection.c

+2 −7

Original line number	Diff line number	Diff line
		@@ -341,14 +341,10 @@ int paste_selection(struct tty_struct *tty)
		struct tty_ldisc *ld;
		DECLARE_WAITQUEUE(wait, current);


		console_lock();
		poke_blanked_console();
		console_unlock();

		/* FIXME: wtf is this supposed to achieve ? */
		ld = tty_ldisc_ref(tty);
		if (!ld)
		ld = tty_ldisc_ref_wait(tty);

		/* FIXME: this is completely unsafe */
		@@ -361,8 +357,7 @@ int paste_selection(struct tty_struct *tty)
		}
		count = sel_buffer_lth - pasted;
		count = min(count, tty->receive_room);
		tty->ldisc->ops->receive_buf(tty, sel_buffer + pasted,
		NULL, count);
		ld->ops->receive_buf(tty, sel_buffer + pasted, NULL, count);
		pasted += count;
		}
		remove_wait_queue(&vc->paste_wait, &wait);

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