ipack: save carrier owner to allow device to get it

There was not any kind of protection against carrier driver removal.
In this way, device driver can 'get' the carrier driver when it is
using it.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ipack/carriers/tpci200.c

@@ -572,7 +572,8 @@ static int tpci200_pci_probe(struct pci_dev *pdev,
 	/* Register the carrier in the industry pack bus driver */
 	tpci200->info->ipack_bus = ipack_bus_register(&pdev->dev,
 						      TPCI200_NB_SLOT,
-						      &tpci200_bus_ops);
+						      &tpci200_bus_ops,
+						      THIS_MODULE);
 	if (!tpci200->info->ipack_bus) {
 		dev_err(&pdev->dev,
 			"error registering the carrier on ipack driver\n");

drivers/ipack/ipack.c

@@ -206,7 +206,8 @@ static struct bus_type ipack_bus_type = {
 };
 
 struct ipack_bus_device *ipack_bus_register(struct device *parent, int slots,
-					    const struct ipack_bus_ops *ops)
+					    const struct ipack_bus_ops *ops,
+					    struct module *owner)
 {
 	int bus_nr;
 	struct ipack_bus_device *bus;
@@ -225,6 +226,7 @@ struct ipack_bus_device *ipack_bus_register(struct device *parent, int slots,
 	bus->parent = parent;
 	bus->slots = slots;
 	bus->ops = ops;
+	bus->owner = owner;
 	return bus;
 }
 EXPORT_SYMBOL_GPL(ipack_bus_register);

include/linux/ipack.h

@@ -172,6 +172,7 @@ struct ipack_bus_ops {
  *	@ops: bus operations for the mezzanine drivers
  */
 struct ipack_bus_device {
+	struct module *owner;
 	struct device *parent;
 	int slots;
 	int bus_nr;
@@ -189,7 +190,8 @@ struct ipack_bus_device {
  * available bus device in ipack.
  */
 struct ipack_bus_device *ipack_bus_register(struct device *parent, int slots,
-					    const struct ipack_bus_ops *ops);
+					    const struct ipack_bus_ops *ops,
+					    struct module *owner);
 
 /**
  *	ipack_bus_unregister -- unregister an ipack bus
@@ -265,3 +267,23 @@ void ipack_put_device(struct ipack_device *dev);
 	 .format = (_format), \
 	 .vendor = (vend), \
 	 .device = (dev)
+
+/**
+ * ipack_get_carrier - it increase the carrier ref. counter of
+ *                     the carrier module
+ * @dev: mezzanine device which wants to get the carrier
+ */
+static inline int ipack_get_carrier(struct ipack_device *dev)
+{
+	return try_module_get(dev->bus->owner);
+}
+
+/**
+ * ipack_get_carrier - it decrease the carrier ref. counter of
+ *                     the carrier module
+ * @dev: mezzanine device which wants to get the carrier
+ */
+static inline void ipack_put_carrier(struct ipack_device *dev)
+{
+	module_put(dev->bus->owner);
+}