From: Alan Cox <alan@linux.intel.com>
Date: Mon, 14 May 2012 13:51:22 +0000 (+0100)
Subject: tty: Allow uart_register/unregister/register
X-Git-Tag: firefly_0821_release~7541^2~1141
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=3c867337cdb88f7b31f9fcf07003e97d408fcd26;p=firefly-linux-kernel-4.4.55.git

tty: Allow uart_register/unregister/register

commit 1e66cded334e6cea596c72f6f650eec351b1e959 upstream.

This is legitimate but because we don't clear the drv->state pointer in the
unregister code causes a bogus BUG().

Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=42880
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 6bc20d77395e..de5e33fc1290 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2325,6 +2325,7 @@ void uart_unregister_driver(struct uart_driver *drv)
 	tty_unregister_driver(p);
 	put_tty_driver(p);
 	kfree(drv->state);
+	drv->state = NULL;
 	drv->tty_driver = NULL;
 }