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llist.h revision 1.2 
      1 /*	$NetBSD: llist.h,v 1.2 2021/12/19 00:54:54 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	*llh_first;
     40 };
     41 
     42 struct llist_node {
     43 	struct llist_node	*llh_next;
     44 };
     45 
     46 static inline void
     47 init_llist_head(struct llist_head *head)
     48 {
     49 
     50 	head->llh_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 = (head->llh_first == NULL);
     61 	membar_enter();
     62 
     63 	return empty;
     64 }
     65 
     66 static inline bool
     67 llist_add(struct llist_node *node, struct llist_head *head)
     68 {
     69 	struct llist_node *first;
     70 
     71 	do {
     72 		first = head->llh_first;
     73 		node->llh_next = first;
     74 		membar_exit();
     75 	} while (atomic_cas_ptr(&head->llh_first, first, node) != first);
     76 
     77 	return first == NULL;
     78 }
     79 
     80 static inline struct llist_node *
     81 llist_del_all(struct llist_head *head)
     82 {
     83 	struct llist_node *first;
     84 
     85 	first = atomic_swap_ptr(&head->llh_first, NULL);
     86 	membar_enter();
     87 
     88 	return first;
     89 }
     90 
     91 static inline struct llist_node *
     92 llist_del_first(struct llist_head *head)
     93 {
     94 	struct llist_node *first;
     95 
     96 	do {
     97 		first = head->llh_first;
     98 		membar_datadep_consumer();
     99 	} while (atomic_cas_ptr(&head->llh_first, first, first->llh_next)
    100 	    != first);
    101 	membar_enter();
    102 
    103 	return first;
    104 }
    105 
    106 #define	llist_for_each_entry_safe(ENTRY, TMP, NODE, FIELD)		      \
    107 	for ((ENTRY) = ((NODE) == NULL ? NULL :				      \
    108 			llist_entry(NODE, typeof(*(ENTRY)), FIELD));	      \
    109 		(ENTRY) == NULL ? 0 :					      \
    110 		    (membar_datadep_consumer(),				      \
    111 			(TMP) = list_entry((ENTRY)->FIELD.llh_next,	      \
    112 			    typeof(*(ENTRY)), FIELD),			      \
    113 			1);						      \
    114 		 (ENTRY) = (TMP))
    115 
    116 #endif	/* _LINUX_LLIST_H_ */
    117