[PATCH v2] platform/x86: acer-wmi: reject missing gaming WMI results

[Yousef Alhouseen]

WMI_gaming_execute_u32_u64() returns success when firmware supplies
no output object, leaving the caller output untouched. Gaming getters
then inspect an uninitialized result value.

When the caller requests an output value, return -ENOMSG if firmware
supplies no object. Preserve a NULL output pointer as the supported way
for callers to ignore the result.

Signed-off-by: Yousef Alhouseen <alhouseenyousef@xxxxxxxxx>
---
Changes in v2:
- Preserve NULL as the supported output-ignore case.
- Only reject a missing firmware object when output was requested.

 drivers/platform/x86/acer-wmi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index e0eaaefb13d0..61ae622c93d9 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1581,7 +1581,9 @@ static int WMI_gaming_execute_u32_u64(u32 method_id, u32 in, u64 *out)
 		return -EIO;
 
 	obj = result.pointer;
-	if (obj && out) {
+	if (!obj && out) {
+		ret = -ENOMSG;
+	} else if (obj && out) {
 		switch (obj->type) {
 		case ACPI_TYPE_INTEGER:
 			*out = obj->integer.value;
-- 
2.55.0