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>

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 8e9b4be..60b7b69 100644 (file)
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -341,15 +341,11 @@ 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);
+       ld = tty_ldisc_ref_wait(tty);
 
        /* FIXME: this is completely unsafe */
        add_wait_queue(&vc->paste_wait, &wait);
@@ -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);