From: Alan Cox <alan@linux.intel.com>
Date: Wed, 9 May 2012 16:03:19 +0000 (+0100)
Subject: tty: drop the pty lock during hangup
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b1d679afd766;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

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>
---

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index d6fa8429f3f..59af3945ea8 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);
 	}
 }