[4.2.y-ckt stable] Patch "staging/speakup: Use tty_ldisc_ref() for paste kworker" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    staging/speakup: Use tty_ldisc_ref() for paste kworker

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From e4eec1dff2dbd04408d287c8a7867240b8bc76b7 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter at hurleysoftware.com>
Date: Sun, 10 Jan 2016 22:40:58 -0800
Subject: 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 at hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/staging/speakup/selection.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/speakup/selection.c b/drivers/staging/speakup/selection.c
index a031570..ed68b2c 100644
--- a/drivers/staging/speakup/selection.c
+++ b/drivers/staging/speakup/selection.c
@@ -141,7 +141,9 @@ 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);
@@ -161,6 +163,7 @@ 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);
 }

--
1.9.1