mei: bus: prevent hardware module unload if device on bus is active

The hardware module should not be unloaded if the bus
has active devices.
Get get_/put_ bus parent module upon client device
connection/disconnection, to prevent the hardware managing
module to disappear underneath.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 3bb1f1500f6b..b67f15b53067 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -542,6 +542,37 @@ out:
 EXPORT_SYMBOL_GPL(mei_cldev_disable);
 
 /**
+ * mei_cl_bus_module_get - acquire module of the underlying
+ *    hw module.
+ *
+ * @cl: host client
+ *
+ * Return: true on success; false if the module was removed.
+ */
+bool mei_cl_bus_module_get(struct mei_cl *cl)
+{
+	struct mei_cl_device *cldev = cl->cldev;
+
+	if (!cldev)
+		return true;
+
+	return try_module_get(cldev->bus->dev->driver->owner);
+}
+
+/**
+ * mei_cl_bus_module_put -  release the underlying hw module.
+ *
+ * @cl: host client
+ */
+void mei_cl_bus_module_put(struct mei_cl *cl)
+{
+	struct mei_cl_device *cldev = cl->cldev;
+
+	if (cldev)
+		module_put(cldev->bus->dev->driver->owner);
+}
+
+/**
  * mei_cl_device_find - find matching entry in the driver id table
  *
  * @cldev: me client device