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Subject[PATCH 3.19.y-ckt 32/47] staging/speakup: Use tty_ldisc_ref() for paste kworker
Date
3.19.8-ckt15 -stable review patch.  If anyone has any objections, please let me know.

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

From: Peter Hurley <peter@hurleysoftware.com>

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>
Signed-off-by: Kamal Mostafa <kamal@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 507fc9a..fb6a686 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
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