From 6ee50aaa9a20c7c11c964c249440857ab58ece36 Mon Sep 17 00:00:00 2001
From: "Darren Hart (VMware)" <dvhart@infradead.org>
Date: Tue, 6 Jun 2017 10:13:49 -0700
Subject: [PATCH] platform/x86: wmi: Instantiate all devices before adding them
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Git-commit: 6ee50aaa9a20c7c11c964c249440857ab58ece36
Patch-mainline: v4.13-rc1
References: FATE#325842

At some point, we will want sub-drivers to get references to other
devices on the same WMI bus. This change is needed to avoid races.

This ends up simplifying the setup code and fixing some leaks, too.

This is based on the original work of Andy Lutomirski <luto@kernel.org>,
but includes several modifications, many in response to review from
Michał Kępień <kernel@kempniu.pl>:

  https://www.spinics.net/lists/platform-driver-x86/msg08201.html

Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/platform/x86/wmi.c |   49 ++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 20 deletions(-)

--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -796,7 +796,7 @@ static struct device_type wmi_type_data
 	.release = wmi_dev_release,
 };
 
-static int wmi_create_device(struct device *wmi_bus_dev,
+static void wmi_create_device(struct device *wmi_bus_dev,
 			     const struct guid_block *gblock,
 			     struct wmi_block *wblock,
 			     struct acpi_device *device)
@@ -852,7 +852,7 @@ static int wmi_create_device(struct devi
 
 	}
 
-	return device_register(&wblock->dev.dev);
+	device_initialize(&wblock->dev.dev);
 }
 
 static void wmi_free_devices(struct acpi_device *device)
@@ -863,10 +863,7 @@ static void wmi_free_devices(struct acpi
 	list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
 		if (wblock->acpi_device == device) {
 			list_del(&wblock->list);
-			if (wblock->dev.dev.bus)
-				device_unregister(&wblock->dev.dev);
-			else
-				kfree(wblock);
+			device_unregister(&wblock->dev.dev);
 		}
 	}
 }
@@ -899,11 +896,11 @@ static bool guid_already_parsed(struct a
 static int parse_wdg(struct device *wmi_bus_dev, struct acpi_device *device)
 {
 	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
-	union acpi_object *obj;
 	const struct guid_block *gblock;
-	struct wmi_block *wblock;
+	struct wmi_block *wblock, *next;
+	union acpi_object *obj;
 	acpi_status status;
-	int retval;
+	int retval = 0;
 	u32 i, total;
 
 	status = acpi_evaluate_object(device->handle, "_WDG", NULL, &out);
@@ -936,19 +933,15 @@ static int parse_wdg(struct device *wmi_
 			continue;
 
 		wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
-		if (!wblock)
-			return -ENOMEM;
+		if (!wblock) {
+			retval = -ENOMEM;
+			break;
+		}
 
 		wblock->acpi_device = device;
 		wblock->gblock = gblock[i];
 
-		retval = wmi_create_device(wmi_bus_dev, &gblock[i],
-					   wblock, device);
-		if (retval) {
-			put_device(&wblock->dev.dev);
-			wmi_free_devices(device);
-			goto out_free_pointer;
-		}
+		wmi_create_device(wmi_bus_dev, &gblock[i], wblock, device);
 
 		list_add_tail(&wblock->list, &wmi_block_list);
 
@@ -958,11 +951,27 @@ static int parse_wdg(struct device *wmi_
 		}
 	}
 
-	retval = 0;
+	/*
+	 * Now that all of the devices are created, add them to the
+	 * device tree and probe subdrivers.
+	 */
+	list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
+		if (wblock->acpi_device != device)
+			continue;
+
+		retval = device_add(&wblock->dev.dev);
+		if (retval) {
+			dev_err(wmi_bus_dev, "failed to register %pULL\n",
+				wblock->gblock.guid);
+			if (debug_event)
+				wmi_method_enable(wblock, 0);
+			list_del(&wblock->list);
+			put_device(&wblock->dev.dev);
+		}
+	}
 
 out_free_pointer:
 	kfree(out.pointer);
-
 	return retval;
 }