1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 #include <linux/compiler_types.h> 3 4 #ifndef __always_inline 5 #define __always_inline inline 6 #endif 7 8 /** 9 * __struct_group() - Create a mirrored named and anonyomous struct 10 * 11 * @TAG: The tag name for the named sub-struct (usually empty) 12 * @NAME: The identifier name of the mirrored sub-struct 13 * @ATTRS: Any struct attributes (usually empty) 14 * @MEMBERS: The member declarations for the mirrored structs 15 * 16 * Used to create an anonymous union of two structs with identical layout 17 * and size: one anonymous and one named. The former's members can be used 18 * normally without sub-struct naming, and the latter can be used to 19 * reason about the start, end, and size of the group of struct members. 20 * The named struct can also be explicitly tagged for layer reuse, as well 21 * as both having struct attributes appended. 22 */ 23 #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \ 24 union { \ 25 struct { MEMBERS } ATTRS; \ 26 struct TAG { MEMBERS } ATTRS NAME; \ 27 } 28 29 /** 30 * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union 31 * 32 * @TYPE: The type of each flexible array element 33 * @NAME: The name of the flexible array member 34 * 35 * In order to have a flexible array member in a union or alone in a 36 * struct, it needs to be wrapped in an anonymous struct with at least 1 37 * named member, but that member can be empty. 38 */ 39 #define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ 40 struct { \ 41 struct { } __empty_ ## NAME; \ 42 TYPE NAME[]; \ 43 } 44