bus: mhi: core: Pass module owner during client driver registration

The module owner field can be used to prevent the removal of kernel
modules when there are any device files associated with it opened in
userspace. Hence, modify the API to pass module owner field. For
convenience, module_mhi_driver() macro is used which takes care of
passing the module owner through THIS_MODULE of the module of the
driver and also avoiding the use of specifying the default MHI client
driver register/unregister routines.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200324061050.14845-2-manivannan.sadhasivam@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/mhi/core/init.c

@@ -1189,7 +1189,7 @@ static int mhi_driver_remove(struct device *dev)
 	return 0;
 }
 
-int mhi_driver_register(struct mhi_driver *mhi_drv)
+int __mhi_driver_register(struct mhi_driver *mhi_drv, struct module *owner)
 {
 	struct device_driver *driver = &mhi_drv->driver;
 
@@ -1197,12 +1197,13 @@ int mhi_driver_register(struct mhi_driver *mhi_drv)
 		return -EINVAL;
 
 	driver->bus = &mhi_bus_type;
+	driver->owner = owner;
 	driver->probe = mhi_driver_probe;
 	driver->remove = mhi_driver_remove;
 
 	return driver_register(driver);
 }
-EXPORT_SYMBOL_GPL(mhi_driver_register);
+EXPORT_SYMBOL_GPL(__mhi_driver_register);
 
 void mhi_driver_unregister(struct mhi_driver *mhi_drv)
 {

include/linux/mhi.h

@@ -514,11 +514,28 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
  */
 void mhi_unregister_controller(struct mhi_controller *mhi_cntrl);
 
+/*
+ * module_mhi_driver() - Helper macro for drivers that don't do
+ * anything special other than using default mhi_driver_register() and
+ * mhi_driver_unregister().  This eliminates a lot of boilerplate.
+ * Each module may only use this macro once.
+ */
+#define module_mhi_driver(mhi_drv) \
+	module_driver(mhi_drv, mhi_driver_register, \
+		      mhi_driver_unregister)
+
+/*
+ * Macro to avoid include chaining to get THIS_MODULE
+ */
+#define mhi_driver_register(mhi_drv) \
+	__mhi_driver_register(mhi_drv, THIS_MODULE)
+
 /**
- * mhi_driver_register - Register driver with MHI framework
+ * __mhi_driver_register - Register driver with MHI framework
  * @mhi_drv: Driver associated with the device
+ * @owner: The module owner
  */
-int mhi_driver_register(struct mhi_driver *mhi_drv);
+int __mhi_driver_register(struct mhi_driver *mhi_drv, struct module *owner);
 
 /**
  * mhi_driver_unregister - Unregister a driver for mhi_devices