From b1d679afd766cf425ba1cd2a0fd17451bd212f4a Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Wed, 9 May 2012 17:03:19 +0100
Subject: [PATCH] tty: drop the pty lock during hangup

In theory we don't need it, in practice we are hitting some ill understood
deadlock when we don't drop it. The old code dropped it here so we are not
undoing anything problematic for pty. If pty could be unloaded it would be
a problem but it can't.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/pty.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index d6fa8429f3ff24..59af3945ea859c 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -63,7 +63,9 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
 		        mutex_unlock(&devpts_mutex);
 		}
 #endif
+		tty_unlock(tty);
 		tty_vhangup(tty->link);
+		tty_lock(tty);
 	}
 }
 
-- 
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