ACPI: WMI: Survive BIOS with duplicate GUIDs

It would appear that in BIOS's with nVidia hooks, the GUID
05901221-D566-11D1-B2F0-00A0C9062910 is duplicated. For now, the simplest
solution is to just ignore any duplicate GUIDs. These particular hooks are not
currently supported/ used in the kernel, so whoever does that can figure out
what the 'right' solution should be (if there's a better one).

http://bugzilla.kernel.org/show_bug.cgi?id=14846

Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: Oldřich Jedlička <oldium.pro@seznam.cz>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index cc9ad740bda1..b104302fea0a 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -714,6 +714,22 @@ static int wmi_class_init(void)
         return ret;
 }
 
+static bool guid_already_parsed(const char *guid_string)
+{
+        struct guid_block *gblock;
+        struct wmi_block *wblock;
+        struct list_head *p;
+
+        list_for_each(p, &wmi_blocks.list) {
+                wblock = list_entry(p, struct wmi_block, list);
+                gblock = &wblock->gblock;
+
+                if (strncmp(gblock->guid, guid_string, 16) == 0)
+                        return true;
+        }
+        return false;
+}
+
 /*
  * Parse the _WDG method for the GUID data blocks
  */
@@ -723,6 +739,7 @@ static __init acpi_status parse_wdg(acpi_handle handle)
         union acpi_object *obj;
         struct guid_block *gblock;
         struct wmi_block *wblock;
+        char guid_string[37];
         acpi_status status;
         u32 i, total;
 
@@ -745,6 +762,19 @@ static __init acpi_status parse_wdg(acpi_handle handle)
         memcpy(gblock, obj->buffer.pointer, obj->buffer.length);
 
         for (i = 0; i < total; 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.
+                */
+                if (guid_already_parsed(gblock[i].guid) == true) {
+                        wmi_gtoa(gblock[i].guid, guid_string);
+                        printk(KERN_INFO PREFIX "Skipping duplicate GUID %s\n",
+                                guid_string);
+                        continue;
+                }
                 wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
                 if (!wblock)
                         return AE_NO_MEMORY;