WMI: Cater for multiple events with same GUID

WMI data blocks can contain WMI events with the same GUID but with
different notifiy_ids, for example volume up/down hotkeys.
This patch enables a single event handler to be registered and
unregistered against all events with same GUID but different
notify_ids.  Since an event handler is passed the notify_id of
an event it can can differentiate between the different events.

The patch also ensures we only register and unregister a device per
unique GUID.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

1 files changed, 72 insertions, 61 deletions

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index aecd9a9b549f..b8e5383eab0c 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -549,21 +549,34 @@ acpi_status wmi_install_notify_handler(const char *guid,
 wmi_notify_handler handler, void *data)
 {
         struct wmi_block *block;
-        acpi_status status;
+        acpi_status status = AE_NOT_EXIST;
+        char tmp[16], guid_input[16];
+        struct list_head *p;
 
         if (!guid || !handler)
                 return AE_BAD_PARAMETER;
 
-        if (!find_guid(guid, &block))
-                return AE_NOT_EXIST;
+        wmi_parse_guid(guid, tmp);
+        wmi_swap_bytes(tmp, guid_input);
 
-        if (block->handler && block->handler != wmi_notify_debug)
-                return AE_ALREADY_ACQUIRED;
+        list_for_each(p, &wmi_block_list) {
+                acpi_status wmi_status;
+                block = list_entry(p, struct wmi_block, list);
 
-        block->handler = handler;
-        block->handler_data = data;
+                if (memcmp(block->gblock.guid, guid_input, 16) == 0) {
+                        if (block->handler &&
+                            block->handler != wmi_notify_debug)
+                                return AE_ALREADY_ACQUIRED;
 
-        status = wmi_method_enable(block, 1);
+                        block->handler = handler;
+                        block->handler_data = data;
+
+                        wmi_status = wmi_method_enable(block, 1);
+                        if ((wmi_status != AE_OK) ||
+                            ((wmi_status == AE_OK) && (status == AE_NOT_EXIST)))
+                                status = wmi_status;
+                }
+        }
 
         return status;
 }
@@ -577,24 +590,40 @@ EXPORT_SYMBOL_GPL(wmi_install_notify_handler);
 acpi_status wmi_remove_notify_handler(const char *guid)
 {
         struct wmi_block *block;
-        acpi_status status = AE_OK;
+        acpi_status status = AE_NOT_EXIST;
+        char tmp[16], guid_input[16];
+        struct list_head *p;
 
         if (!guid)
                 return AE_BAD_PARAMETER;
 
-        if (!find_guid(guid, &block))
-                return AE_NOT_EXIST;
+        wmi_parse_guid(guid, tmp);
+        wmi_swap_bytes(tmp, guid_input);
 
-        if (!block->handler || block->handler == wmi_notify_debug)
-                return AE_NULL_ENTRY;
+        list_for_each(p, &wmi_block_list) {
+                acpi_status wmi_status;
+                block = list_entry(p, struct wmi_block, list);
 
-        if (debug_event) {
-                block->handler = wmi_notify_debug;
-        } else {
-                status = wmi_method_enable(block, 0);
-                block->handler = NULL;
-                block->handler_data = NULL;
+                if (memcmp(block->gblock.guid, guid_input, 16) == 0) {
+                        if (!block->handler ||
+                            block->handler == wmi_notify_debug)
+                                return AE_NULL_ENTRY;
+
+                        if (debug_event) {
+                                block->handler = wmi_notify_debug;
+                                status = AE_OK;
+                        } else {
+                                wmi_status = wmi_method_enable(block, 0);
+                                block->handler = NULL;
+                                block->handler_data = NULL;
+                                if ((wmi_status != AE_OK) ||
+                                    ((wmi_status == AE_OK) &&
+                                     (status == AE_NOT_EXIST)))
+                                        status = wmi_status;
+                        }
+                }
         }
+
         return status;
 }
 EXPORT_SYMBOL_GPL(wmi_remove_notify_handler);
@@ -705,22 +734,11 @@ static struct class wmi_class = {
         .dev_attrs = wmi_dev_attrs,
 };
 
-static struct wmi_block *wmi_create_device(const struct guid_block *gblock,
-                                           acpi_handle handle)
+static int wmi_create_device(const struct guid_block *gblock,
+                             struct wmi_block *wblock, acpi_handle handle)
 {
-        struct wmi_block *wblock;
-        int error;
         char guid_string[37];
 
-        wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
-        if (!wblock) {
-                error = -ENOMEM;
-                goto err_out;
-        }
-
-        wblock->handle = handle;
-        wblock->gblock = *gblock;
-
         wblock->dev.class = &wmi_class;
 
         wmi_gtoa(gblock->guid, guid_string);
@@ -728,17 +746,7 @@ static struct wmi_block *wmi_create_device(const struct guid_block *gblock,
 
         dev_set_drvdata(&wblock->dev, wblock);
 
-        error = device_register(&wblock->dev);
-        if (error)
-                goto err_free;
-
-        list_add_tail(&wblock->list, &wmi_block_list);
-        return wblock;
-
-err_free:
-        kfree(wblock);
-err_out:
-        return ERR_PTR(error);
+        return device_register(&wblock->dev);
 }
 
 static void wmi_free_devices(void)
@@ -747,7 +755,8 @@ static void wmi_free_devices(void)
 
         /* Delete devices for all the GUIDs */
         list_for_each_entry_safe(wblock, next, &wmi_block_list, list)
-                device_unregister(&wblock->dev);
+                if (wblock->dev.class)
+                        device_unregister(&wblock->dev);
 }
 
 static bool guid_already_parsed(const char *guid_string)
@@ -770,7 +779,6 @@ static acpi_status parse_wdg(acpi_handle handle)
         union acpi_object *obj;
         const struct guid_block *gblock;
         struct wmi_block *wblock;
-        char guid_string[37];
         acpi_status status;
         int retval;
         u32 i, total;
@@ -792,28 +800,31 @@ static acpi_status parse_wdg(acpi_handle handle)
         total = obj->buffer.length / sizeof(struct guid_block);
 
         for (i = 0; i < total; i++) {
+                if (debug_dump_wdg)
+                        wmi_dump_wdg(&gblock[i]);
+
+                wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
+                if (!wblock)
+                        return AE_NO_MEMORY;
+
+                wblock->handle = handle;
+                wblock->gblock = gblock[i];
+
                 /*
                   Some WMI devices, like those for nVidia hooks, have a
                   duplicate GUID. It's not clear what we should do in this
-                  case yet, so for now, we'll just ignore the duplicate.
-                  Anyone who wants to add support for that device can come
-                  up with a better workaround for the mess then.
+                  case yet, so for now, we'll just ignore the duplicate
+                  for device creation.
                 */
-                if (guid_already_parsed(gblock[i].guid) == true) {
-                        wmi_gtoa(gblock[i].guid, guid_string);
-                        pr_info("Skipping duplicate GUID %s\n", guid_string);
-                        continue;
+                if (!guid_already_parsed(gblock[i].guid)) {
+                        retval = wmi_create_device(&gblock[i], wblock, handle);
+                        if (retval) {
+                                wmi_free_devices();
+                                break;
+                        }
                 }
 
-                if (debug_dump_wdg)
-                        wmi_dump_wdg(&gblock[i]);
-
-                wblock = wmi_create_device(&gblock[i], handle);
-                if (IS_ERR(wblock)) {
-                        retval = PTR_ERR(wblock);
-                        wmi_free_devices();
-                        break;
-                }
+                list_add_tail(&wblock->list, &wmi_block_list);
 
                 if (debug_event) {
                         wblock->handler = wmi_notify_debug;