[mirror_frr.git] / lib / atomlist.h

/*
 * Copyright (c) 2016-2019  David Lamparter, for NetDEF, Inc.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _FRR_ATOMLIST_H
#define _FRR_ATOMLIST_H

#include "typesafe.h"
#include "frratomic.h"

/* pointer with lock/deleted/invalid bit in lowest bit
 *
 * for atomlist/atomsort, "locked" means "this pointer can't be updated, the
 * item is being deleted".  it is permissible to assume the item will indeed
 * be deleted (as there are no replace/etc. ops in this).
 *
 * in general, lowest 2/3 bits on 32/64bit architectures are available for
 * uses like this; the only thing that will really break this is putting an
 * atomlist_item in a struct with "packed" attribute.  (it'll break
 * immediately and consistently.) -- don't do that.
 *
 * ATOMPTR_USER is currently unused (and available for atomic hash or skiplist
 * implementations.)
 */
typedef uintptr_t atomptr_t;
#define ATOMPTR_MASK (UINTPTR_MAX - 3)
#define ATOMPTR_LOCK (1)
#define ATOMPTR_USER (2)
#define ATOMPTR_NULL (0)

static inline atomptr_t atomptr_i(void *val)
{
	atomptr_t atomval = (atomptr_t)val;

	assert(!(atomval & ATOMPTR_LOCK));
	return atomval;
}
static inline void *atomptr_p(atomptr_t val)
{
	return (void *)(val & ATOMPTR_MASK);
}
static inline bool atomptr_l(atomptr_t val)
{
	return (bool)(val & ATOMPTR_LOCK);
}
static inline bool atomptr_u(atomptr_t val)
{
	return (bool)(val & ATOMPTR_USER);
}


/* the problem with, find(), find_gteq() and find_lt() on atomic lists is that
 * they're neither an "acquire" nor a "release" operation;  the element that
 * was found is still on the list and doesn't change ownership.  Therefore,
 * an atomic transition in ownership state can't be implemented.
 *
 * Contrast this with add() or pop(): both function calls atomically transfer
 * ownership of an item to or from the list, which makes them "acquire" /
 * "release" operations.
 *
 * What can be implemented atomically is a "find_pop()", i.e. try to locate an
 * item and atomically try to remove it if found.  It's not currently
 * implemented but can be added when needed.
 *
 * Either way - for find(), generally speaking, if you need to use find() on
 * a list then the whole thing probably isn't well-suited to atomic
 * implementation and you'll need to have extra locks around to make it work
 * correctly.
 */
#ifdef WNO_ATOMLIST_UNSAFE_FIND
# define atomic_find_warn
#else
# define atomic_find_warn __attribute__((_DEPRECATED( \
	"WARNING: find() on atomic lists cannot be atomic by principle; " \
	"check code to make sure usage pattern is OK and if it is, use " \
	"#define WNO_ATOMLIST_UNSAFE_FIND")))
#endif


/* single-linked list, unsorted/arbitrary.
 * can be used as queue with add_tail / pop
 *
 * all operations are lock-free, but not neccessarily wait-free.  this means
 * that there is no state where the system as a whole stops making process,
 * but it *is* possible that a *particular* thread is delayed by some time.
 *
 * the only way for this to happen is for other threads to continuously make
 * updates.  an inactive / blocked / deadlocked other thread cannot cause such
 * delays, and to cause such delays a thread must be heavily hitting the list -
 * it's a rather theoretical concern.
 */

/* don't use these structs directly */
struct atomlist_item {
	_Atomic atomptr_t next;
};
#define atomlist_itemp(val) ((struct atomlist_item *)atomptr_p(val))

struct atomlist_head {
	_Atomic atomptr_t first, last;
	_Atomic size_t count;
};

/* use as:
 *
 * PREDECL_ATOMLIST(namelist)
 * struct name {
 *   struct namelist_item nlitem;
 * }
 * DECLARE_ATOMLIST(namelist, struct name, nlitem)
 */
#define PREDECL_ATOMLIST(prefix)                                               \
struct prefix ## _head { struct atomlist_head ah; };                           \
struct prefix ## _item { struct atomlist_item ai; };

#define INIT_ATOMLIST(var) { }

#define DECLARE_ATOMLIST(prefix, type, field)                                  \
macro_inline void prefix ## _add_head(struct prefix##_head *h, type *item)     \
{	atomlist_add_head(&h->ah, &item->field.ai); }                          \
macro_inline void prefix ## _add_tail(struct prefix##_head *h, type *item)     \
{	atomlist_add_tail(&h->ah, &item->field.ai); }                          \
macro_inline void prefix ## _del_hint(struct prefix##_head *h, type *item,     \
		_Atomic atomptr_t *hint)                                       \
{	atomlist_del_hint(&h->ah, &item->field.ai, hint); }                    \
macro_inline type *prefix ## _del(struct prefix##_head *h, type *item)         \
{	atomlist_del_hint(&h->ah, &item->field.ai, NULL);                      \
	/* TODO: Return NULL if not found */                                   \
	return item; }                                                         \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{	char *p = (char *)atomlist_pop(&h->ah);                                \
	return p ? (type *)(p - offsetof(type, field)) : NULL; }               \
macro_inline type *prefix ## _first(struct prefix##_head *h)                   \
{	char *p = atomptr_p(atomic_load_explicit(&h->ah.first,                 \
				memory_order_acquire));                        \
	return p ? (type *)(p - offsetof(type, field)) : NULL; }               \
macro_inline type *prefix ## _next(struct prefix##_head *h, type *item)        \
{	char *p = atomptr_p(atomic_load_explicit(&item->field.ai.next,         \
				memory_order_acquire));                        \
	return p ? (type *)(p - offsetof(type, field)) : NULL; }               \
macro_inline type *prefix ## _next_safe(struct prefix##_head *h, type *item)   \
{	return item ? prefix##_next(h, item) : NULL; }                         \
macro_inline size_t prefix ## _count(struct prefix##_head *h)                  \
{	return atomic_load_explicit(&h->ah.count, memory_order_relaxed); }     \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	assert(prefix ## _count(h) == 0);                                      \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
/* ... */

/* add_head:
 * - contention on ->first pointer
 * - return implies completion
 */
void atomlist_add_head(struct atomlist_head *h, struct atomlist_item *item);

/* add_tail:
 * - concurrent add_tail can cause wait but has progress guarantee
 * - return does NOT imply completion.  completion is only guaranteed after
 *   all other add_tail operations that started before this add_tail have
 *   completed as well.
 */
void atomlist_add_tail(struct atomlist_head *h, struct atomlist_item *item);

/* del/del_hint:
 *
 * OWNER MUST HOLD REFERENCE ON ITEM TO BE DELETED, ENSURING NO OTHER THREAD
 * WILL TRY TO DELETE THE SAME ITEM.  DELETING INCLUDES pop().
 *
 * as with all deletions, threads that started reading earlier may still hold
 * pointers to the deleted item.  completion is however guaranteed for all
 * reads starting later.
 */
void atomlist_del_hint(struct atomlist_head *h, struct atomlist_item *item,
		_Atomic atomptr_t *hint);

/* pop:
 *
 * as with all deletions, threads that started reading earlier may still hold
 * pointers to the deleted item.  completion is however guaranteed for all
 * reads starting later.
 */
struct atomlist_item *atomlist_pop(struct atomlist_head *h);


struct atomsort_item {
	_Atomic atomptr_t next;
};
#define atomsort_itemp(val) ((struct atomsort_item *)atomptr_p(val))

struct atomsort_head {
	_Atomic atomptr_t first;
	_Atomic size_t count;
};

#define _PREDECL_ATOMSORT(prefix)                                              \
struct prefix ## _head { struct atomsort_head ah; };                           \
struct prefix ## _item { struct atomsort_item ai; };

#define INIT_ATOMSORT_UNIQ(var)		{ }
#define INIT_ATOMSORT_NONUNIQ(var)	{ }

#define _DECLARE_ATOMSORT(prefix, type, field, cmpfn_nuq, cmpfn_uq)            \
macro_inline void prefix ## _init(struct prefix##_head *h)                     \
{                                                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline void prefix ## _fini(struct prefix##_head *h)                     \
{                                                                              \
	assert(h->ah.count == 0);                                              \
	memset(h, 0, sizeof(*h));                                              \
}                                                                              \
macro_inline type *prefix ## _add(struct prefix##_head *h, type *item)         \
{                                                                              \
	struct atomsort_item *p;                                               \
	p = atomsort_add(&h->ah, &item->field.ai, cmpfn_uq);                   \
	return container_of_null(p, type, field.ai);                           \
}                                                                              \
macro_inline type *prefix ## _first(struct prefix##_head *h)                   \
{                                                                              \
	struct atomsort_item *p;                                               \
	p = atomptr_p(atomic_load_explicit(&h->ah.first,                       \
				memory_order_acquire));                        \
	return container_of_null(p, type, field.ai);                           \
}                                                                              \
macro_inline type *prefix ## _next(struct prefix##_head *h, type *item)        \
{                                                                              \
	struct atomsort_item *p;                                               \
	p = atomptr_p(atomic_load_explicit(&item->field.ai.next,               \
				memory_order_acquire));                        \
	return container_of_null(p, type, field.ai);                           \
}                                                                              \
macro_inline type *prefix ## _next_safe(struct prefix##_head *h, type *item)   \
{                                                                              \
	return item ? prefix##_next(h, item) : NULL;                           \
}                                                                              \
atomic_find_warn                                                               \
macro_inline type *prefix ## _find_gteq(struct prefix##_head *h,               \
		const type *item)                                              \
{                                                                              \
	type *p = prefix ## _first(h);                                         \
	while (p && cmpfn_nuq(&p->field.ai, &item->field.ai) < 0)              \
		p = prefix ## _next(h, p);                                     \
	return p;                                                              \
}                                                                              \
atomic_find_warn                                                               \
macro_inline type *prefix ## _find_lt(struct prefix##_head *h,                 \
		const type *item)                                              \
{                                                                              \
	type *p = prefix ## _first(h), *prev = NULL;                           \
	while (p && cmpfn_nuq(&p->field.ai, &item->field.ai) < 0)              \
		p = prefix ## _next(h, (prev = p));                            \
	return prev;                                                           \
}                                                                              \
macro_inline void prefix ## _del_hint(struct prefix##_head *h, type *item,     \
		_Atomic atomptr_t *hint)                                       \
{                                                                              \
	atomsort_del_hint(&h->ah, &item->field.ai, hint);                      \
}                                                                              \
macro_inline type *prefix ## _del(struct prefix##_head *h, type *item)         \
{                                                                              \
	atomsort_del_hint(&h->ah, &item->field.ai, NULL);                      \
	/* TODO: Return NULL if not found */                                   \
	return item;                                                           \
}                                                                              \
macro_inline size_t prefix ## _count(struct prefix##_head *h)                  \
{                                                                              \
	return atomic_load_explicit(&h->ah.count, memory_order_relaxed);       \
}                                                                              \
macro_inline type *prefix ## _pop(struct prefix##_head *h)                     \
{                                                                              \
	struct atomsort_item *p = atomsort_pop(&h->ah);                        \
	return p ? container_of(p, type, field.ai) : NULL;                     \
}                                                                              \
/* ... */

#define PREDECL_ATOMSORT_UNIQ(prefix)                                          \
	_PREDECL_ATOMSORT(prefix)
#define DECLARE_ATOMSORT_UNIQ(prefix, type, field, cmpfn)                      \
                                                                               \
macro_inline int prefix ## __cmp(const struct atomsort_item *a,                \
		const struct atomsort_item *b)                                 \
{                                                                              \
	return cmpfn(container_of(a, type, field.ai),                          \
			container_of(b, type, field.ai));                      \
}                                                                              \
                                                                               \
_DECLARE_ATOMSORT(prefix, type, field,                                         \
		prefix ## __cmp, prefix ## __cmp)                              \
                                                                               \
atomic_find_warn                                                               \
macro_inline type *prefix ## _find(struct prefix##_head *h, const type *item)  \
{                                                                              \
	type *p = prefix ## _first(h);                                         \
	int cmpval = 0;                                                        \
	while (p && (cmpval = cmpfn(p, item)) < 0)                             \
		p = prefix ## _next(h, p);                                     \
	if (!p || cmpval > 0)                                                  \
		return NULL;                                                   \
	return p;                                                              \
}                                                                              \
/* ... */

#define PREDECL_ATOMSORT_NONUNIQ(prefix)                                       \
	_PREDECL_ATOMSORT(prefix)
#define DECLARE_ATOMSORT_NONUNIQ(prefix, type, field, cmpfn)                   \
                                                                               \
macro_inline int prefix ## __cmp(const struct atomsort_item *a,                \
		const struct atomsort_item *b)                                 \
{                                                                              \
	return cmpfn(container_of(a, type, field.ai),                          \
			container_of(b, type, field.ai));                      \
}                                                                              \
macro_inline int prefix ## __cmp_uq(const struct atomsort_item *a,             \
		const struct atomsort_item *b)                                 \
{                                                                              \
	int cmpval = cmpfn(container_of(a, type, field.ai),                    \
			container_of(b, type, field.ai));                      \
	if (cmpval)                                                            \
		return cmpval;                                                 \
	if (a < b)                                                             \
		return -1;                                                     \
	if (a > b)                                                             \
		return 1;                                                      \
	return 0;                                                              \
}                                                                              \
                                                                               \
_DECLARE_ATOMSORT(prefix, type, field,                                         \
		prefix ## __cmp, prefix ## __cmp_uq)                           \
/* ... */

struct atomsort_item *atomsort_add(struct atomsort_head *h,
		struct atomsort_item *item, int (*cmpfn)(
			const struct atomsort_item *,
			const struct atomsort_item *));

void atomsort_del_hint(struct atomsort_head *h,
		struct atomsort_item *item, _Atomic atomptr_t *hint);

struct atomsort_item *atomsort_pop(struct atomsort_head *h);

#endif /* _FRR_ATOMLIST_H */
Commit	Line	Data
bcea0c0f DL	1	/*
	2	* Copyright (c) 2016-2019 David Lamparter, for NetDEF, Inc.
	3	*
	4	* Permission to use, copy, modify, and distribute this software for any
	5	* purpose with or without fee is hereby granted, provided that the above
	6	* copyright notice and this permission notice appear in all copies.
	7	*
	8	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	9	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	10	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	11	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	12	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	13	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	14	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	15	*/
	16
	17	#ifndef _FRR_ATOMLIST_H
	18	#define _FRR_ATOMLIST_H
	19
	20	#include "typesafe.h"
	21	#include "frratomic.h"
	22
	23	/* pointer with lock/deleted/invalid bit in lowest bit
	24	*
	25	* for atomlist/atomsort, "locked" means "this pointer can't be updated, the
	26	* item is being deleted". it is permissible to assume the item will indeed
	27	* be deleted (as there are no replace/etc. ops in this).
	28	*
	29	* in general, lowest 2/3 bits on 32/64bit architectures are available for
	30	* uses like this; the only thing that will really break this is putting an
	31	* atomlist_item in a struct with "packed" attribute. (it'll break
	32	* immediately and consistently.) -- don't do that.
	33	*
	34	* ATOMPTR_USER is currently unused (and available for atomic hash or skiplist
	35	* implementations.)
	36	*/
	37	typedef uintptr_t atomptr_t;
	38	#define ATOMPTR_MASK (UINTPTR_MAX - 3)
	39	#define ATOMPTR_LOCK (1)
	40	#define ATOMPTR_USER (2)
	41	#define ATOMPTR_NULL (0)
	42
	43	static inline atomptr_t atomptr_i(void *val)
	44	{
	45	atomptr_t atomval = (atomptr_t)val;
	46
	47	assert(!(atomval & ATOMPTR_LOCK));
	48	return atomval;
	49	}
	50	static inline void *atomptr_p(atomptr_t val)
	51	{
	52	return (void *)(val & ATOMPTR_MASK);
	53	}
	54	static inline bool atomptr_l(atomptr_t val)
	55	{
	56	return (bool)(val & ATOMPTR_LOCK);
	57	}
	58	static inline bool atomptr_u(atomptr_t val)
	59	{
	60	return (bool)(val & ATOMPTR_USER);
	61	}
	62
	63
	64	/* the problem with, find(), find_gteq() and find_lt() on atomic lists is that
65	* they're neither an "acquire" nor a "release" operation; the element that
66	* was found is still on the list and doesn't change ownership. Therefore,
67	* an atomic transition in ownership state can't be implemented.
68	*
69	* Contrast this with add() or pop(): both function calls atomically transfer
70	* ownership of an item to or from the list, which makes them "acquire" /
71	* "release" operations.
72	*
73	* What can be implemented atomically is a "find_pop()", i.e. try to locate an
74	* item and atomically try to remove it if found. It's not currently
75	* implemented but can be added when needed.
76	*
77	* Either way - for find(), generally speaking, if you need to use find() on
78	* a list then the whole thing probably isn't well-suited to atomic
79	* implementation and you'll need to have extra locks around to make it work
80	* correctly.
81	*/
82	#ifdef WNO_ATOMLIST_UNSAFE_FIND
83	# define atomic_find_warn
84	#else
85	# define atomic_find_warn __attribute__((_DEPRECATED( \
86	"WARNING: find() on atomic lists cannot be atomic by principle; " \
87	"check code to make sure usage pattern is OK and if it is, use " \
88	"#define WNO_ATOMLIST_UNSAFE_FIND")))
89	#endif
90
91
92	/* single-linked list, unsorted/arbitrary.
93	* can be used as queue with add_tail / pop
94	*
95	* all operations are lock-free, but not neccessarily wait-free. this means
96	* that there is no state where the system as a whole stops making process,
97	* but it is possible that a particular thread is delayed by some time.
98	*
99	* the only way for this to happen is for other threads to continuously make
100	* updates. an inactive / blocked / deadlocked other thread cannot cause such
101	* delays, and to cause such delays a thread must be heavily hitting the list -
102	* it's a rather theoretical concern.
103	*/
104
105	/* don't use these structs directly */
106	struct atomlist_item {
107	_Atomic atomptr_t next;
108	};
109	#define atomlist_itemp(val) ((struct atomlist_item *)atomptr_p(val))
110
111	struct atomlist_head {
112	_Atomic atomptr_t first, last;
113	_Atomic size_t count;
114	};
115
116	/* use as:
117	*
118	* PREDECL_ATOMLIST(namelist)
119	* struct name {
120	* struct namelist_item nlitem;
121	* }
122	* DECLARE_ATOMLIST(namelist, struct name, nlitem)
123	*/
124	#define PREDECL_ATOMLIST(prefix) \
125	struct prefix ## _head { struct atomlist_head ah; }; \
126	struct prefix ## _item { struct atomlist_item ai; };
127
128	#define INIT_ATOMLIST(var) { }
129
130	#define DECLARE_ATOMLIST(prefix, type, field) \
131	macro_inline void prefix ## _add_head(struct prefix##_head h, type item) \
132	{ atomlist_add_head(&h->ah, &item->field.ai); } \
133	macro_inline void prefix ## _add_tail(struct prefix##_head h, type item) \
134	{ atomlist_add_tail(&h->ah, &item->field.ai); } \
135	macro_inline void prefix ## _del_hint(struct prefix##_head h, type item, \
136	_Atomic atomptr_t *hint) \
137	{ atomlist_del_hint(&h->ah, &item->field.ai, hint); } \
da098d78 SW	138	macro_inline type prefix ## _del(struct prefix##_head h, type *item) \
	139	{ atomlist_del_hint(&h->ah, &item->field.ai, NULL); \
	140	/* TODO: Return NULL if not found */ \
	141	return item; } \
bcea0c0f DL	142	macro_inline type prefix ## _pop(struct prefix##_head h) \
	143	{ char p = (char )atomlist_pop(&h->ah); \
	144	return p ? (type *)(p - offsetof(type, field)) : NULL; } \
	145	macro_inline type prefix ## _first(struct prefix##_head h) \
	146	{ char *p = atomptr_p(atomic_load_explicit(&h->ah.first, \
	147	memory_order_acquire)); \
	148	return p ? (type *)(p - offsetof(type, field)) : NULL; } \
	149	macro_inline type prefix ## _next(struct prefix##_head h, type *item) \
	150	{ char *p = atomptr_p(atomic_load_explicit(&item->field.ai.next, \
	151	memory_order_acquire)); \
	152	return p ? (type *)(p - offsetof(type, field)) : NULL; } \
	153	macro_inline type prefix ## _next_safe(struct prefix##_head h, type *item) \
	154	{ return item ? prefix##_next(h, item) : NULL; } \
	155	macro_inline size_t prefix ## _count(struct prefix##_head *h) \
	156	{ return atomic_load_explicit(&h->ah.count, memory_order_relaxed); } \
9680a2af DL	157	macro_inline void prefix ## _init(struct prefix##_head *h) \
	158	{ \
	159	memset(h, 0, sizeof(*h)); \
	160	} \
	161	macro_inline void prefix ## _fini(struct prefix##_head *h) \
	162	{ \
	163	assert(prefix ## _count(h) == 0); \
	164	memset(h, 0, sizeof(*h)); \
	165	} \
bcea0c0f DL	166	/* ... */
	167
	168	/* add_head:
	169	* - contention on ->first pointer
	170	* - return implies completion
	171	*/
	172	void atomlist_add_head(struct atomlist_head h, struct atomlist_item item);
	173
	174	/* add_tail:
	175	* - concurrent add_tail can cause wait but has progress guarantee
	176	* - return does NOT imply completion. completion is only guaranteed after
	177	* all other add_tail operations that started before this add_tail have
	178	* completed as well.
	179	*/
	180	void atomlist_add_tail(struct atomlist_head h, struct atomlist_item item);
	181
	182	/* del/del_hint:
	183	*
	184	* OWNER MUST HOLD REFERENCE ON ITEM TO BE DELETED, ENSURING NO OTHER THREAD
	185	* WILL TRY TO DELETE THE SAME ITEM. DELETING INCLUDES pop().
	186	*
	187	* as with all deletions, threads that started reading earlier may still hold
	188	* pointers to the deleted item. completion is however guaranteed for all
	189	* reads starting later.
	190	*/
	191	void atomlist_del_hint(struct atomlist_head h, struct atomlist_item item,
	192	_Atomic atomptr_t *hint);
	193
	194	/* pop:
	195	*
	196	* as with all deletions, threads that started reading earlier may still hold
	197	* pointers to the deleted item. completion is however guaranteed for all
	198	* reads starting later.
	199	*/
	200	struct atomlist_item atomlist_pop(struct atomlist_head h);
	201
	202
	203
	204	struct atomsort_item {
	205	_Atomic atomptr_t next;
	206	};
	207	#define atomsort_itemp(val) ((struct atomsort_item *)atomptr_p(val))
	208
	209	struct atomsort_head {
	210	_Atomic atomptr_t first;
	211	_Atomic size_t count;
	212	};
	213
	214	#define _PREDECL_ATOMSORT(prefix) \
	215	struct prefix ## _head { struct atomsort_head ah; }; \
	216	struct prefix ## _item { struct atomsort_item ai; };
	217
	218	#define INIT_ATOMSORT_UNIQ(var) { }
	219	#define INIT_ATOMSORT_NONUNIQ(var) { }
	220
	221	#define _DECLARE_ATOMSORT(prefix, type, field, cmpfn_nuq, cmpfn_uq) \
	222	macro_inline void prefix ## _init(struct prefix##_head *h) \
	223	{ \
	224	memset(h, 0, sizeof(*h)); \
	225	} \
	226	macro_inline void prefix ## _fini(struct prefix##_head *h) \
	227	{ \
	228	assert(h->ah.count == 0); \
	229	memset(h, 0, sizeof(*h)); \
230	} \
231	macro_inline type prefix ## _add(struct prefix##_head h, type *item) \
232	{ \
233	struct atomsort_item *p; \
234	p = atomsort_add(&h->ah, &item->field.ai, cmpfn_uq); \
235	return container_of_null(p, type, field.ai); \
236	} \
237	macro_inline type prefix ## _first(struct prefix##_head h) \
238	{ \
239	struct atomsort_item *p; \
240	p = atomptr_p(atomic_load_explicit(&h->ah.first, \
241	memory_order_acquire)); \
242	return container_of_null(p, type, field.ai); \
243	} \
244	macro_inline type prefix ## _next(struct prefix##_head h, type *item) \
245	{ \
246	struct atomsort_item *p; \
247	p = atomptr_p(atomic_load_explicit(&item->field.ai.next, \
248	memory_order_acquire)); \
249	return container_of_null(p, type, field.ai); \
250	} \
251	macro_inline type prefix ## _next_safe(struct prefix##_head h, type *item) \
252	{ \
253	return item ? prefix##_next(h, item) : NULL; \
254	} \
255	atomic_find_warn \
256	macro_inline type prefix ## _find_gteq(struct prefix##_head h, \
257	const type *item) \
258	{ \
259	type *p = prefix ## _first(h); \
260	while (p && cmpfn_nuq(&p->field.ai, &item->field.ai) < 0) \
261	p = prefix ## _next(h, p); \
262	return p; \
263	} \
264	atomic_find_warn \
265	macro_inline type prefix ## _find_lt(struct prefix##_head h, \
266	const type *item) \
267	{ \
268	type p = prefix ## _first(h), prev = NULL; \
269	while (p && cmpfn_nuq(&p->field.ai, &item->field.ai) < 0) \
270	p = prefix ## _next(h, (prev = p)); \
271	return prev; \
272	} \
273	macro_inline void prefix ## _del_hint(struct prefix##_head h, type item, \
274	_Atomic atomptr_t *hint) \
275	{ \
276	atomsort_del_hint(&h->ah, &item->field.ai, hint); \
277	} \
da098d78	278	macro_inline type prefix ## _del(struct prefix##_head h, type *item) \
bcea0c0f DL	279	{ \
bcea0c0f DL	280	atomsort_del_hint(&h->ah, &item->field.ai, NULL); \
da098d78 SW	281	/* TODO: Return NULL if not found */ \
da098d78 SW	282	return item; \
bcea0c0f DL	283	} \
	284	macro_inline size_t prefix ## _count(struct prefix##_head *h) \
	285	{ \
	286	return atomic_load_explicit(&h->ah.count, memory_order_relaxed); \
	287	} \
	288	macro_inline type prefix ## _pop(struct prefix##_head h) \
	289	{ \
	290	struct atomsort_item *p = atomsort_pop(&h->ah); \
	291	return p ? container_of(p, type, field.ai) : NULL; \
	292	} \
	293	/* ... */
	294
	295	#define PREDECL_ATOMSORT_UNIQ(prefix) \
	296	_PREDECL_ATOMSORT(prefix)
	297	#define DECLARE_ATOMSORT_UNIQ(prefix, type, field, cmpfn) \
	298	\
	299	macro_inline int prefix ## __cmp(const struct atomsort_item *a, \
	300	const struct atomsort_item *b) \
	301	{ \
	302	return cmpfn(container_of(a, type, field.ai), \
	303	container_of(b, type, field.ai)); \
	304	} \
	305	\
	306	_DECLARE_ATOMSORT(prefix, type, field, \
	307	prefix ## __cmp, prefix ## __cmp) \
	308	\
	309	atomic_find_warn \
	310	macro_inline type prefix ## _find(struct prefix##_head h, const type *item) \
	311	{ \
	312	type *p = prefix ## _first(h); \
	313	int cmpval = 0; \
	314	while (p && (cmpval = cmpfn(p, item)) < 0) \
	315	p = prefix ## _next(h, p); \
	316	if (!p \|\| cmpval > 0) \
	317	return NULL; \
	318	return p; \
	319	} \
	320	/* ... */
	321
	322	#define PREDECL_ATOMSORT_NONUNIQ(prefix) \
	323	_PREDECL_ATOMSORT(prefix)
	324	#define DECLARE_ATOMSORT_NONUNIQ(prefix, type, field, cmpfn) \
	325	\
	326	macro_inline int prefix ## __cmp(const struct atomsort_item *a, \
	327	const struct atomsort_item *b) \
	328	{ \
	329	return cmpfn(container_of(a, type, field.ai), \
	330	container_of(b, type, field.ai)); \
	331	} \
	332	macro_inline int prefix ## __cmp_uq(const struct atomsort_item *a, \
	333	const struct atomsort_item *b) \
	334	{ \
	335	int cmpval = cmpfn(container_of(a, type, field.ai), \
	336	container_of(b, type, field.ai)); \
	337	if (cmpval) \
	338	return cmpval; \
	339	if (a < b) \
	340	return -1; \
	341	if (a > b) \
	342	return 1; \
	343	return 0; \
	344	} \
	345	\
	346	_DECLARE_ATOMSORT(prefix, type, field, \
347	prefix ## __cmp, prefix ## __cmp_uq) \
348	/* ... */
349
350	struct atomsort_item atomsort_add(struct atomsort_head h,
351	struct atomsort_item item, int (cmpfn)(
352	const struct atomsort_item *,
353	const struct atomsort_item *));
354
355	void atomsort_del_hint(struct atomsort_head *h,
356	struct atomsort_item item, _Atomic atomptr_t hint);
357
358	struct atomsort_item atomsort_pop(struct atomsort_head h);
359
360	#endif /* _FRR_ATOMLIST_H */