staging/speakup: Use tty_ldisc_ref() for paste kworker

peterhurley · gregkh · commit f4f9edcf9b52 · 2016-01-26T23:17:54.000-08:00
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: 28a821c ("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
@@ -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);
 }
 
