[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>

2 files changed, 8 insertions, 2 deletions

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index d814bb1dcb05..397147a7054f 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1940,6 +1940,9 @@ 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);
@@ -2006,7 +2009,7 @@ 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;
 
@@ -2018,15 +2021,17 @@ 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);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 86501a3de2ac..f9fdf97506ea 100644
--- a/include/linux/serial_core.h
+++ b/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;