[PATCH] SERIAL: Fix oops when removing suspended serial port

[SERIAL] Fix oops when removing suspended serial port

A serial card might have been removed when the system is resumed.
This results in a suspended port being shut down, which results in
the ports shutdown method being called twice in a row.  This causes
BUGs.  Avoid this by tracking the suspended state separately from
the initialised state.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: maximilian attems <maks@sternwelten.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

drivers/serial/serial_core.c

@@ -1932,6 +1932,9 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 	if (state->info && state->info->flags & UIF_INITIALIZED) {
 		const struct uart_ops *ops = port->ops;
 
+		state->info->flags = (state->info->flags & ~UIF_INITIALIZED)
+				     | UIF_SUSPENDED;
+
 		spin_lock_irq(&port->lock);
 		ops->stop_tx(port);
 		ops->set_mctrl(port, 0);
@@ -1991,7 +1994,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 		console_start(port->cons);
 	}
 
-	if (state->info && state->info->flags & UIF_INITIALIZED) {
+	if (state->info && state->info->flags & UIF_SUSPENDED) {
 		const struct uart_ops *ops = port->ops;
 		int ret;
 
@@ -2003,15 +2006,17 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 			ops->set_mctrl(port, port->mctrl);
 			ops->start_tx(port);
 			spin_unlock_irq(&port->lock);
+			state->info->flags |= UIF_INITIALIZED;
 		} else {
 			/*
 			 * Failed to resume - maybe hardware went away?
 			 * Clear the "initialized" flag so we won't try
 			 * to call the low level drivers shutdown method.
 			 */
-			state->info->flags &= ~UIF_INITIALIZED;
 			uart_shutdown(state);
 		}
+
+		state->info->flags &= ~UIF_SUSPENDED;
 	}
 
 	mutex_unlock(&state->mutex);

include/linux/serial_core.h

@@ -319,6 +319,7 @@ struct uart_info {
 #define UIF_CTS_FLOW		((__force uif_t) (1 << 26))
 #define UIF_NORMAL_ACTIVE	((__force uif_t) (1 << 29))
 #define UIF_INITIALIZED		((__force uif_t) (1 << 31))
+#define UIF_SUSPENDED		((__force uif_t) (1 << 30))
 
 	int			blocked_open;