lib: container_of() - Always return NULL if input pointer is NULL

diff --git a/src/lib/macros.h b/src/lib/macros.h
index fb5923dc3c620289daca88e060a1ed1c626687b5..3a3db2c3ed91293a4a7f151abf0ab279ab9479cb 100644 (file)
--- a/src/lib/macros.h
+++ b/src/lib/macros.h
@@ -26,9 +26,15 @@
 #define CONST_PTR_OFFSET(ptr, offset) \
        ((const void *) (((uintptr_t) (ptr)) + ((size_t) (offset))))
 
+static inline const char *container_of_ptr(const void *ptr, size_t offset)
+{
+       if (ptr == NULL)
+               return NULL;
+       return (const char *)ptr - offset;
+}
 #define container_of(ptr, type, name) \
-       (type *)((char *)(ptr) - offsetof(type, name) + \
-                COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE(ptr, &((type *) 0)->name))
+       (type *)(container_of_ptr(ptr, offsetof(type, name) + \
+                COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE(ptr, &((type *) 0)->name)))
 
 /* Don't use simply MIN/MAX, as they're often defined elsewhere in include
    files that are included after this file generating tons of warnings. */