diff options
Diffstat (limited to 'include/linux/container_of.h')
| -rw-r--r-- | include/linux/container_of.h | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/container_of.h b/include/linux/container_of.h new file mode 100644 index 000000000..713890c86 --- /dev/null +++ b/include/linux/container_of.h @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CONTAINER_OF_H +#define _LINUX_CONTAINER_OF_H + +#include <linux/build_bug.h> +#include <linux/stddef.h> + +#define typeof_member(T, m) typeof(((T*)0)->m) + +/** + * container_of - cast a member of a structure out to the containing structure + * @ptr: the pointer to the member. + * @type: the type of the container struct this is embedded in. + * @member: the name of the member within the struct. + * + * WARNING: any const qualifier of @ptr is lost. + */ +#define container_of(ptr, type, member) ({ \ + void *__mptr = (void *)(ptr); \ + static_assert(__same_type(*(ptr), ((type *)0)->member) || \ + __same_type(*(ptr), void), \ + "pointer type mismatch in container_of()"); \ + ((type *)(__mptr - offsetof(type, member))); }) + +/** + * container_of_const - cast a member of a structure out to the containing + * structure and preserve the const-ness of the pointer + * @ptr: the pointer to the member + * @type: the type of the container struct this is embedded in. + * @member: the name of the member within the struct. + */ +#define container_of_const(ptr, type, member) \ + _Generic(ptr, \ + const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\ + default: ((type *)container_of(ptr, type, member)) \ + ) + +#endif /* _LINUX_CONTAINER_OF_H */ |