staging/speakup: Use tty_ldisc_ref() for paste kworker

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")
Cc: <stable@vger.kernel.org>
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 aa5ab6c80ed4ffefc12aaca9c1337e403371d478..41ef099b7aa69f345d33998c46e2bce11ad691d9 100644 (file)
--- a/drivers/staging/speakup/selection.c
+++ b/drivers/staging/speakup/selection.c
@@ -142,7 +142,9 @@ 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;
        tty_buffer_lock_exclusive(&vc->port);
 
        add_wait_queue(&vc->paste_wait, &wait);
@@ -162,6 +164,7 @@ static void __speakup_paste_selection(struct work_struct *work)
 
        tty_buffer_unlock_exclusive(&vc->port);
        tty_ldisc_deref(ld);
+tty_unref:
        tty_kref_put(tty);
 }