diff options
Diffstat (limited to 'kernel/include/containter_of.h')
| -rw-r--r-- | kernel/include/containter_of.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/kernel/include/containter_of.h b/kernel/include/containter_of.h new file mode 100644 index 0000000..766847a --- /dev/null +++ b/kernel/include/containter_of.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef CONTAINER_OF +#define CONTAINER_OF + +#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) +#define __static_assert(expr, msg, ...) _Static_assert(expr, msg) +#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) +#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 |