1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_CONTAINER_OF_H |
3 | #define _LINUX_CONTAINER_OF_H |
4 | |
5 | #include <linux/build_bug.h> |
6 | #include <linux/stddef.h> |
7 | |
8 | #define typeof_member(T, m) typeof(((T*)0)->m) |
9 | |
10 | /** |
11 | * container_of - cast a member of a structure out to the containing structure |
12 | * @ptr: the pointer to the member. |
13 | * @type: the type of the container struct this is embedded in. |
14 | * @member: the name of the member within the struct. |
15 | * |
16 | * WARNING: any const qualifier of @ptr is lost. |
17 | */ |
18 | #define container_of(ptr, type, member) ({ \ |
19 | void *__mptr = (void *)(ptr); \ |
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \ |
21 | __same_type(*(ptr), void), \ |
22 | "pointer type mismatch in container_of()"); \ |
23 | ((type *)(__mptr - offsetof(type, member))); }) |
24 | |
25 | /** |
26 | * container_of_const - cast a member of a structure out to the containing |
27 | * structure and preserve the const-ness of the pointer |
28 | * @ptr: the pointer to the member |
29 | * @type: the type of the container struct this is embedded in. |
30 | * @member: the name of the member within the struct. |
31 | */ |
32 | #define container_of_const(ptr, type, member) \ |
33 | _Generic(ptr, \ |
34 | const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\ |
35 | default: ((type *)container_of(ptr, type, member)) \ |
36 | ) |
37 | |
38 | #endif /* _LINUX_CONTAINER_OF_H */ |
39 | |