greybus: connection: switch to using spin_lock_irqsave/spin_lock_irqrestore excluisvely

We know that it is a bad idea to explicitly enable IRQs when we don't
don't know if they were already off before we disabled, so switch to the
save _irqsave and _irqrestore functions.

Ultimately, we need to review places in the Greybus drivers where IRQs
are disabled and remove unnecessary instances. This is only an interim
step.

This code will never run from hard irq context, as it is already taking
mutex in the path.

Testing done: booted EVT2.0, ran suspend/resume test app with a period
of 20s for a few dozen cycles.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Jeffrey Carlyle <jcarlyle@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/connection.c

@@ -572,7 +572,7 @@ static int gb_connection_ping(struct gb_connection *connection)
  * DISCONNECTING.
  */
 static void gb_connection_cancel_operations(struct gb_connection *connection,
-						int errno)
+						int errno, unsigned long *flags)
 	__must_hold(&connection->lock)
 {
 	struct gb_operation *operation;
@@ -581,7 +581,7 @@ static void gb_connection_cancel_operations(struct gb_connection *connection,
 		operation = list_last_entry(&connection->operations,
 						struct gb_operation, links);
 		gb_operation_get(operation);
-		spin_unlock_irq(&connection->lock);
+		spin_unlock_irqrestore(&connection->lock, *flags);
 
 		if (gb_operation_is_incoming(operation))
 			gb_operation_cancel_incoming(operation, errno);
@@ -590,7 +590,7 @@ static void gb_connection_cancel_operations(struct gb_connection *connection,
 
 		gb_operation_put(operation);
 
-		spin_lock_irq(&connection->lock);
+		spin_lock_irqsave(&connection->lock, *flags);
 	}
 }
 
@@ -601,7 +601,7 @@ static void gb_connection_cancel_operations(struct gb_connection *connection,
  */
 static void
 gb_connection_flush_incoming_operations(struct gb_connection *connection,
-						int errno)
+						int errno, unsigned long *flags)
 	__must_hold(&connection->lock)
 {
 	struct gb_operation *operation;
@@ -621,13 +621,13 @@ gb_connection_flush_incoming_operations(struct gb_connection *connection,
 		if (!incoming)
 			break;
 
-		spin_unlock_irq(&connection->lock);
+		spin_unlock_irqrestore(&connection->lock, *flags);
 
 		/* FIXME: flush, not cancel? */
 		gb_operation_cancel_incoming(operation, errno);
 		gb_operation_put(operation);
 
-		spin_lock_irq(&connection->lock);
+		spin_lock_irqsave(&connection->lock, *flags);
 	}
 }
 
@@ -644,15 +644,16 @@ gb_connection_flush_incoming_operations(struct gb_connection *connection,
 static int _gb_connection_enable(struct gb_connection *connection, bool rx)
 {
 	int ret;
+	unsigned long flags;
 
 	/* Handle ENABLED_TX -> ENABLED transitions. */
 	if (connection->state == GB_CONNECTION_STATE_ENABLED_TX) {
 		if (!(connection->handler && rx))
 			return 0;
 
-		spin_lock_irq(&connection->lock);
+		spin_lock_irqsave(&connection->lock, flags);
 		connection->state = GB_CONNECTION_STATE_ENABLED;
-		spin_unlock_irq(&connection->lock);
+		spin_unlock_irqrestore(&connection->lock, flags);
 
 		return 0;
 	}
@@ -669,12 +670,12 @@ static int _gb_connection_enable(struct gb_connection *connection, bool rx)
 	if (ret)
 		goto err_svc_connection_destroy;
 
-	spin_lock_irq(&connection->lock);
+	spin_lock_irqsave(&connection->lock, flags);
 	if (connection->handler && rx)
 		connection->state = GB_CONNECTION_STATE_ENABLED;
 	else
 		connection->state = GB_CONNECTION_STATE_ENABLED_TX;
-	spin_unlock_irq(&connection->lock);
+	spin_unlock_irqrestore(&connection->lock, flags);
 
 	ret = gb_connection_control_connected(connection);
 	if (ret)
@@ -685,10 +686,10 @@ static int _gb_connection_enable(struct gb_connection *connection, bool rx)
 err_control_disconnecting:
 	gb_connection_control_disconnecting(connection);
 
-	spin_lock_irq(&connection->lock);
+	spin_lock_irqsave(&connection->lock, flags);
 	connection->state = GB_CONNECTION_STATE_DISCONNECTING;
-	gb_connection_cancel_operations(connection, -ESHUTDOWN);
-	spin_unlock_irq(&connection->lock);
+	gb_connection_cancel_operations(connection, -ESHUTDOWN, &flags);
+	spin_unlock_irqrestore(&connection->lock, flags);
 
 	/* Transmit queue should already be empty. */
 	gb_connection_hd_cport_flush(connection);
@@ -754,16 +755,18 @@ EXPORT_SYMBOL_GPL(gb_connection_enable_tx);
 
 void gb_connection_disable_rx(struct gb_connection *connection)
 {
+	unsigned long flags;
+
 	mutex_lock(&connection->mutex);
 
-	spin_lock_irq(&connection->lock);
+	spin_lock_irqsave(&connection->lock, flags);
 	if (connection->state != GB_CONNECTION_STATE_ENABLED) {
-		spin_unlock_irq(&connection->lock);
+		spin_unlock_irqrestore(&connection->lock, flags);
 		goto out_unlock;
 	}
 	connection->state = GB_CONNECTION_STATE_ENABLED_TX;
-	gb_connection_flush_incoming_operations(connection, -ESHUTDOWN);
-	spin_unlock_irq(&connection->lock);
+	gb_connection_flush_incoming_operations(connection, -ESHUTDOWN, &flags);
+	spin_unlock_irqrestore(&connection->lock, flags);
 
 	trace_gb_connection_disable(connection);
 
@@ -786,6 +789,8 @@ void gb_connection_mode_switch_complete(struct gb_connection *connection)
 
 void gb_connection_disable(struct gb_connection *connection)
 {
+	unsigned long flags;
+
 	mutex_lock(&connection->mutex);
 
 	if (connection->state == GB_CONNECTION_STATE_DISABLED)
@@ -795,10 +800,10 @@ void gb_connection_disable(struct gb_connection *connection)
 
 	gb_connection_control_disconnecting(connection);
 
-	spin_lock_irq(&connection->lock);
+	spin_lock_irqsave(&connection->lock, flags);
 	connection->state = GB_CONNECTION_STATE_DISCONNECTING;
-	gb_connection_cancel_operations(connection, -ESHUTDOWN);
-	spin_unlock_irq(&connection->lock);
+	gb_connection_cancel_operations(connection, -ESHUTDOWN, &flags);
+	spin_unlock_irqrestore(&connection->lock, flags);
 
 	gb_connection_hd_cport_flush(connection);
 
@@ -825,6 +830,8 @@ EXPORT_SYMBOL_GPL(gb_connection_disable);
 /* Disable a connection without communicating with the remote end. */
 void gb_connection_disable_forced(struct gb_connection *connection)
 {
+	unsigned long flags;
+
 	mutex_lock(&connection->mutex);
 
 	if (connection->state == GB_CONNECTION_STATE_DISABLED)
@@ -832,10 +839,10 @@ void gb_connection_disable_forced(struct gb_connection *connection)
 
 	trace_gb_connection_disable(connection);
 
-	spin_lock_irq(&connection->lock);
+	spin_lock_irqsave(&connection->lock, flags);
 	connection->state = GB_CONNECTION_STATE_DISABLED;
-	gb_connection_cancel_operations(connection, -ESHUTDOWN);
-	spin_unlock_irq(&connection->lock);
+	gb_connection_cancel_operations(connection, -ESHUTDOWN, &flags);
+	spin_unlock_irqrestore(&connection->lock, flags);
 
 	gb_connection_hd_cport_flush(connection);
 	gb_connection_hd_cport_features_disable(connection);