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>

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index cc9ad740bda15266303312fe68ab2586cc1bcfd3..b104302fea0a1e9dbc4a91f82290a185ad244e00 100644 (file)
--- 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;