staging/speakup: Use tty_ldisc_ref() for paste kworker

commit f4f9edcf9b5289ed96113e79fa65a7bf27ecb096 upstream.

As the function documentation for tty_ldisc_ref_wait() notes, it is
only callable from a tty file_operations routine; otherwise there
is no guarantee the ref won't be NULL.

The key difference with the VT's paste_selection() is that is an ioctl,
where __speakup_paste_selection() is completely async kworker, kicked
off from interrupt context.

Fixes: 28a821c30688 ("Staging: speakup: Update __speakup_paste_selection()
       tty (ab)usage to match vt")
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/speakup/selection.c b/drivers/staging/speakup/selection.c
index b9359753784eaf9aee8e94d6d10f53fa3f240a38..364978e63d8dd75d08bd7e7a15e807575bef06af 100644 (file)
--- a/drivers/staging/speakup/selection.c
+++ b/drivers/staging/speakup/selection.c
@@ -139,7 +139,9 @@ static void __speakup_paste_selection(struct work_struct *work)
        struct tty_ldisc *ld;
        DECLARE_WAITQUEUE(wait, current);
 
-       ld = tty_ldisc_ref_wait(tty);
+       ld = tty_ldisc_ref(tty);
+       if (!ld)
+               goto tty_unref;
 
        /* FIXME: this is completely unsafe */
        add_wait_queue(&vc->paste_wait, &wait);
@@ -158,6 +160,7 @@ static void __speakup_paste_selection(struct work_struct *work)
        current->state = TASK_RUNNING;
 
        tty_ldisc_deref(ld);
+tty_unref:
        tty_kref_put(tty);
 }