diff options
Diffstat (limited to 'include/linux/container_of.h')
| -rw-r--r-- | include/linux/container_of.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/include/linux/container_of.h b/include/linux/container_of.h new file mode 100644 index 000000000000..2f4944b791b8 --- /dev/null +++ b/include/linux/container_of.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CONTAINER_OF_H +#define _LINUX_CONTAINER_OF_H + +#include <linux/build_bug.h> +#include <linux/err.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. + * + */ +#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_safe - 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. + * + * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged. + */ +#define container_of_safe(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_safe()"); \ + IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \ + ((type *)(__mptr - offsetof(type, member))); }) + +#endif /* _LINUX_CONTAINER_OF_H */ |