firmware: arm_scmi: provide the mandatory device release callback

sudeep-holla · arndb · commit 46edb8d1322c · 2019-01-30T11:34:42.000+01:00
The device/driver model clearly mandates that bus driver that discover and allocate the device must set the release callback. This callback will be used to free the device after all references have gone away. scmi bus driver is missing the obvious callback which will result in the following warning if the device is unregistered: Device 'scmi_dev.1' does not have a release() function, it is broken and must be fixed. See Documentation/kobject.txt. WARNING at drivers/base/core.c:922 device_release+0x8c/0xa0 Hardware name: ARM LTD Juno Development Platform BIOS EDK II Jan 21 2019 Workqueue: events deferred_probe_work_func pstate: 60000005 (nZCv daif -PAN -UAO) pc : device_release+0x8c/0xa0 lr : device_release+0x8c/0xa0 Call trace: device_release+0x8c/0xa0 kobject_put+0x8c/0x208 device_unregister+0x30/0x78 scmi_device_destroy+0x28/0x50 scmi_probe+0x354/0x5b0 platform_drv_probe+0x58/0xa8 really_probe+0x2c4/0x3e8 driver_probe_device+0x12c/0x148 __device_attach_driver+0xac/0x150 bus_for_each_drv+0x78/0xd8 __device_attach+0xe0/0x168 device_initial_probe+0x24/0x30 bus_probe_device+0xa0/0xa8 deferred_probe_work_func+0x8c/0xe0 process_one_work+0x1f0/0x478 worker_thread+0x22c/0x450 kthread+0x134/0x138 ret_from_fork+0x10/0x1c ---[ end trace 420bdb7f6af50937 ]--- Fix the issue by providing scmi_device_release callback. We have everything required for device release already in scmi_device_destroy, so we just need to move freeing of the device to scmi_device_release. Fixes: 933c504 ("firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices") Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Cc: stable@vger.kernel.org # 4.17+ Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
@@ -119,6 +119,11 @@ void scmi_driver_unregister(struct scmi_driver *driver)
 }
 EXPORT_SYMBOL_GPL(scmi_driver_unregister);
 
+static void scmi_device_release(struct device *dev)
+{
+	kfree(to_scmi_dev(dev));
+}
+
 struct scmi_device *
 scmi_device_create(struct device_node *np, struct device *parent, int protocol)
 {
@@ -138,6 +143,7 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol)
 	scmi_dev->dev.parent = parent;
 	scmi_dev->dev.of_node = np;
 	scmi_dev->dev.bus = &scmi_bus_type;
+	scmi_dev->dev.release = scmi_device_release;
 	dev_set_name(&scmi_dev->dev, "scmi_dev.%d", id);
 
 	retval = device_register(&scmi_dev->dev);
@@ -156,9 +162,8 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol)
 void scmi_device_destroy(struct scmi_device *scmi_dev)
 {
 	scmi_handle_put(scmi_dev->handle);
-	device_unregister(&scmi_dev->dev);
 	ida_simple_remove(&scmi_bus_id, scmi_dev->id);
-	kfree(scmi_dev);
+	device_unregister(&scmi_dev->dev);
 }
 
 void scmi_set_handle(struct scmi_device *scmi_dev)
