ACPICA: Windows compatibility fix: same buffer/string store

Fix a compatibility issue when the same buffer or string is
stored to itself. This has been seen in the field. Previously,
ACPICA would zero out the buffer/string. Now, the operation is
treated as a NOP.

http://bugzilla.acpica.org/show_bug.cgi?id=803

Reported-by: Rezwanul Kabir <[e-mail]>
Signed-off-by: Lin Ming <[e-mail]>
Signed-off-by: Bob Moore <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

drivers/acpi/acpica/exstorob.c

···
 
 	ACPI_FUNCTION_TRACE_PTR(ex_store_buffer_to_buffer, source_desc);
 
+	/* If Source and Target are the same, just return */
+
+	if (source_desc == target_desc) {
+		return_ACPI_STATUS(AE_OK);
+	}
+
 	/* We know that source_desc is a buffer by now */
 
 	buffer = ACPI_CAST_PTR(u8, source_desc->buffer.pointer);
···
 	u8 *buffer;
 
 	ACPI_FUNCTION_TRACE_PTR(ex_store_string_to_string, source_desc);
+
+	/* If Source and Target are the same, just return */
+
+	if (source_desc == target_desc) {
+		return_ACPI_STATUS(AE_OK);
+	}
 
 	/* We know that source_desc is a string by now */