Commit 7bda1910 authored by Sumeet Pawnikar's avatar Sumeet Pawnikar Committed by Rafael J. Wysocki
Browse files

powercap: fix race condition in register_control_type() 



The device becomes visible to userspace via device_register()
even before it fully initialized by idr_init(). If userspace
or another thread tries to register a zone immediately after
device_register(), the control_type_valid() will fail because
the control_type is not yet in the list. The IDR is not yet
initialized, so this race condition causes zone registration
failure.

Move idr_init() and list addition before device_register()
fix the race condition.

Signed-off-by: default avatarSumeet Pawnikar <sumeet4linux@gmail.com>
[ rjw: Subject adjustment, empty line added ]
Link: https://patch.msgid.link/20251205190216.5032-1-sumeet4linux@gmail.com


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 8f0b4cce

drivers/powercap/powercap_sys.c

+11 −5
Original line number Diff line number Diff line
@@ -625,17 +625,23 @@ struct powercap_control_type *powercap_register_control_type( 
	INIT_LIST_HEAD(&control_type->node);

	control_type->dev.class = &powercap_class;

	dev_set_name(&control_type->dev, "%s", name);

	result = device_register(&control_type->dev);

	if (result) {

		put_device(&control_type->dev);

		return ERR_PTR(result);

	}

	idr_init(&control_type->idr);



	mutex_lock(&powercap_cntrl_list_lock);

	list_add_tail(&control_type->node, &powercap_cntrl_list);

	mutex_unlock(&powercap_cntrl_list_lock);



	result = device_register(&control_type->dev);

	if (result) {

		mutex_lock(&powercap_cntrl_list_lock);

		list_del(&control_type->node);

		mutex_unlock(&powercap_cntrl_list_lock);



		idr_destroy(&control_type->idr);

		put_device(&control_type->dev);

		return ERR_PTR(result);

	}



	return control_type;

}

EXPORT_SYMBOL_GPL(powercap_register_control_type);