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llist.h revision 1.5 
      1 /*	$NetBSD: llist.h,v 1.5 2021/12/19 11:39:24 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2018 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef	_LINUX_LLIST_H_
     33 #define	_LINUX_LLIST_H_
     34 
     35 #include <sys/atomic.h>
     36 #include <sys/null.h>
     37 
     38 struct llist_head {
     39 	struct llist_node	*first;
     40 };
     41 
     42 struct llist_node {
     43 	struct llist_node	*next;
     44 };
     45 
     46 static inline void
     47 init_llist_head(struct llist_head *head)
     48 {
     49 
     50 	head->first = NULL;
     51 }
     52 
     53 #define	llist_entry(NODE, TYPE, FIELD)	container_of(NODE, TYPE, FIELD)
     54 
     55 static inline bool
     56 llist_empty(struct llist_head *head)
     57 {
     58 	bool empty;
     59 
     60 	empty = (atomic_load_acquire(&head->first) == NULL);
     61 
     62 	return empty;
     63 }
     64 
     65 static inline bool
     66 llist_add(struct llist_node *node, struct llist_head *head)
     67 {
     68 	struct llist_node *first;
     69 
     70 	do {
     71 		first = head->first;
     72 		node->next = first;
     73 		membar_exit();
     74 	} while (atomic_cas_ptr(&head->first, first, node) != first);
     75 
     76 	return first == NULL;
     77 }
     78 
     79 static inline struct llist_node *
     80 llist_del_all(struct llist_head *head)
     81 {
     82 	struct llist_node *first;
     83 
     84 	first = atomic_swap_ptr(&head->first, NULL);
     85 	membar_enter();
     86 
     87 	return first;
     88 }
     89 
     90 static inline struct llist_node *
     91 llist_del_first(struct llist_head *head)
     92 {
     93 	struct llist_node *first;
     94 
     95 	do {
     96 		first = atomic_load_consume(&head->first);
     97 		if (first == NULL)
     98 			return NULL;
     99 	} while (atomic_cas_ptr(&head->first, first, first->next)
    100 	    != first);
    101 
    102 	return first;
    103 }
    104 
    105 #define	_llist_next(ENTRY, FIELD)					      \
    106 ({									      \
    107 	__typeof__((ENTRY)->FIELD.next) _NODE =				      \
    108 	    atomic_load_consume(&(ENTRY)->FIELD.next);			      \
    109 	(_NODE == NULL ? NULL :						      \
    110 	    llist_entry(_NODE, __typeof__(*(ENTRY)), FIELD));		      \
    111 })
    112 
    113 #define	llist_for_each_safe(NODE, TMP, HEAD)				      \
    114 	for ((NODE) = (HEAD);						      \
    115 		(NODE) && ((TMP) = (NODE)->next, 1);			      \
    116 		(NODE) = (TMP))
    117 
    118 #define	llist_for_each_entry(ENTRY, NODE, FIELD)			      \
    119 	for ((ENTRY) = ((NODE) == NULL ? NULL :				      \
    120 		    (membar_datadep_consumer(),				      \
    121 			llist_entry(NODE, typeof(*(ENTRY)), FIELD)));	      \
    122 		(ENTRY) != NULL;					      \
    123 		(ENTRY) = _llist_next(ENTRY, FIELD))
    124 
    125 #define	llist_for_each_entry_safe(ENTRY, TMP, NODE, FIELD)		      \
    126 	for ((ENTRY) = ((NODE) == NULL ? NULL :				      \
    127 		    (membar_datadep_consumer(),				      \
    128 			llist_entry(NODE, typeof(*(ENTRY)), FIELD)));	      \
    129 		((ENTRY) == NULL ? 0 :					      \
    130 		    ((TMP) = _llist_next(ENTRY, FIELD), 1));		      \
    131 		(ENTRY) = (TMP))
    132 
    133 #endif	/* _LINUX_LLIST_H_ */
    134