[linux-block.git] / include / linux / container_of.h

/* 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 */
Commit	Line	Data
d2a8ebbf AS	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/err.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	*/
	17	#define container_of(ptr, type, member) ({ \
	18	void __mptr = (void )(ptr); \
e1edc277 RV	19	static_assert(__same_type((ptr), ((type )0)->member) \|\| \
	20	__same_type(*(ptr), void), \
	21	"pointer type mismatch in container_of()"); \
d2a8ebbf AS	22	((type *)(__mptr - offsetof(type, member))); })
	23
	24	/**
	25	* container_of_safe - cast a member of a structure out to the containing structure
	26	* @ptr: the pointer to the member.
	27	* @type: the type of the container struct this is embedded in.
	28	* @member: the name of the member within the struct.
	29	*
	30	* If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
	31	*/
	32	#define container_of_safe(ptr, type, member) ({ \
	33	void __mptr = (void )(ptr); \
e1edc277 RV	34	static_assert(__same_type((ptr), ((type )0)->member) \|\| \
	35	__same_type(*(ptr), void), \
	36	"pointer type mismatch in container_of_safe()"); \
d2a8ebbf AS	37	IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \
	38	((type *)(__mptr - offsetof(type, member))); })
	39
	40	#endif /* _LINUX_CONTAINER_OF_H */