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