~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/include/linux/llist.h

Version: ~ [ linux-5.3-rc4 ] ~ [ linux-5.2.8 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.66 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.138 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.189 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.189 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.71 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 #ifndef LLIST_H
  2 #define LLIST_H
  3 /*
  4  * Lock-less NULL terminated single linked list
  5  *
  6  * Cases where locking is not needed:
  7  * If there are multiple producers and multiple consumers, llist_add can be
  8  * used in producers and llist_del_all can be used in consumers simultaneously
  9  * without locking. Also a single consumer can use llist_del_first while
 10  * multiple producers simultaneously use llist_add, without any locking.
 11  *
 12  * Cases where locking is needed:
 13  * If we have multiple consumers with llist_del_first used in one consumer, and
 14  * llist_del_first or llist_del_all used in other consumers, then a lock is
 15  * needed.  This is because llist_del_first depends on list->first->next not
 16  * changing, but without lock protection, there's no way to be sure about that
 17  * if a preemption happens in the middle of the delete operation and on being
 18  * preempted back, the list->first is the same as before causing the cmpxchg in
 19  * llist_del_first to succeed. For example, while a llist_del_first operation
 20  * is in progress in one consumer, then a llist_del_first, llist_add,
 21  * llist_add (or llist_del_all, llist_add, llist_add) sequence in another
 22  * consumer may cause violations.
 23  *
 24  * This can be summarized as follows:
 25  *
 26  *           |   add    | del_first |  del_all
 27  * add       |    -     |     -     |     -
 28  * del_first |          |     L     |     L
 29  * del_all   |          |           |     -
 30  *
 31  * Where, a particular row's operation can happen concurrently with a column's
 32  * operation, with "-" being no lock needed, while "L" being lock is needed.
 33  *
 34  * The list entries deleted via llist_del_all can be traversed with
 35  * traversing function such as llist_for_each etc.  But the list
 36  * entries can not be traversed safely before deleted from the list.
 37  * The order of deleted entries is from the newest to the oldest added
 38  * one.  If you want to traverse from the oldest to the newest, you
 39  * must reverse the order by yourself before traversing.
 40  *
 41  * The basic atomic operation of this list is cmpxchg on long.  On
 42  * architectures that don't have NMI-safe cmpxchg implementation, the
 43  * list can NOT be used in NMI handlers.  So code that uses the list in
 44  * an NMI handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
 45  *
 46  * Copyright 2010,2011 Intel Corp.
 47  *   Author: Huang Ying <ying.huang@intel.com>
 48  *
 49  * This program is free software; you can redistribute it and/or
 50  * modify it under the terms of the GNU General Public License version
 51  * 2 as published by the Free Software Foundation;
 52  *
 53  * This program is distributed in the hope that it will be useful,
 54  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 55  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 56  * GNU General Public License for more details.
 57  *
 58  * You should have received a copy of the GNU General Public License
 59  * along with this program; if not, write to the Free Software
 60  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 61  */
 62 
 63 #include <linux/atomic.h>
 64 #include <linux/kernel.h>
 65 
 66 struct llist_head {
 67         struct llist_node *first;
 68 };
 69 
 70 struct llist_node {
 71         struct llist_node *next;
 72 };
 73 
 74 #define LLIST_HEAD_INIT(name)   { NULL }
 75 #define LLIST_HEAD(name)        struct llist_head name = LLIST_HEAD_INIT(name)
 76 
 77 /**
 78  * init_llist_head - initialize lock-less list head
 79  * @head:       the head for your lock-less list
 80  */
 81 static inline void init_llist_head(struct llist_head *list)
 82 {
 83         list->first = NULL;
 84 }
 85 
 86 /**
 87  * llist_entry - get the struct of this entry
 88  * @ptr:        the &struct llist_node pointer.
 89  * @type:       the type of the struct this is embedded in.
 90  * @member:     the name of the llist_node within the struct.
 91  */
 92 #define llist_entry(ptr, type, member)          \
 93         container_of(ptr, type, member)
 94 
 95 /**
 96  * llist_for_each - iterate over some deleted entries of a lock-less list
 97  * @pos:        the &struct llist_node to use as a loop cursor
 98  * @node:       the first entry of deleted list entries
 99  *
100  * In general, some entries of the lock-less list can be traversed
101  * safely only after being deleted from list, so start with an entry
102  * instead of list head.
103  *
104  * If being used on entries deleted from lock-less list directly, the
105  * traverse order is from the newest to the oldest added entry.  If
106  * you want to traverse from the oldest to the newest, you must
107  * reverse the order by yourself before traversing.
108  */
109 #define llist_for_each(pos, node)                       \
110         for ((pos) = (node); pos; (pos) = (pos)->next)
111 
112 /**
113  * llist_for_each_entry - iterate over some deleted entries of lock-less list of given type
114  * @pos:        the type * to use as a loop cursor.
115  * @node:       the fist entry of deleted list entries.
116  * @member:     the name of the llist_node with the struct.
117  *
118  * In general, some entries of the lock-less list can be traversed
119  * safely only after being removed from list, so start with an entry
120  * instead of list head.
121  *
122  * If being used on entries deleted from lock-less list directly, the
123  * traverse order is from the newest to the oldest added entry.  If
124  * you want to traverse from the oldest to the newest, you must
125  * reverse the order by yourself before traversing.
126  */
127 #define llist_for_each_entry(pos, node, member)                         \
128         for ((pos) = llist_entry((node), typeof(*(pos)), member);       \
129              &(pos)->member != NULL;                                    \
130              (pos) = llist_entry((pos)->member.next, typeof(*(pos)), member))
131 
132 /**
133  * llist_for_each_entry_safe - iterate over some deleted entries of lock-less list of given type
134  *                             safe against removal of list entry
135  * @pos:        the type * to use as a loop cursor.
136  * @n:          another type * to use as temporary storage
137  * @node:       the first entry of deleted list entries.
138  * @member:     the name of the llist_node with the struct.
139  *
140  * In general, some entries of the lock-less list can be traversed
141  * safely only after being removed from list, so start with an entry
142  * instead of list head.
143  *
144  * If being used on entries deleted from lock-less list directly, the
145  * traverse order is from the newest to the oldest added entry.  If
146  * you want to traverse from the oldest to the newest, you must
147  * reverse the order by yourself before traversing.
148  */
149 #define llist_for_each_entry_safe(pos, n, node, member)                        \
150         for (pos = llist_entry((node), typeof(*pos), member);                  \
151              &pos->member != NULL &&                                           \
152                 (n = llist_entry(pos->member.next, typeof(*n), member), true); \
153              pos = n)
154 
155 /**
156  * llist_empty - tests whether a lock-less list is empty
157  * @head:       the list to test
158  *
159  * Not guaranteed to be accurate or up to date.  Just a quick way to
160  * test whether the list is empty without deleting something from the
161  * list.
162  */
163 static inline bool llist_empty(const struct llist_head *head)
164 {
165         return ACCESS_ONCE(head->first) == NULL;
166 }
167 
168 static inline struct llist_node *llist_next(struct llist_node *node)
169 {
170         return node->next;
171 }
172 
173 extern bool llist_add_batch(struct llist_node *new_first,
174                             struct llist_node *new_last,
175                             struct llist_head *head);
176 /**
177  * llist_add - add a new entry
178  * @new:        new entry to be added
179  * @head:       the head for your lock-less list
180  *
181  * Returns true if the list was empty prior to adding this entry.
182  */
183 static inline bool llist_add(struct llist_node *new, struct llist_head *head)
184 {
185         return llist_add_batch(new, new, head);
186 }
187 
188 /**
189  * llist_del_all - delete all entries from lock-less list
190  * @head:       the head of lock-less list to delete all entries
191  *
192  * If list is empty, return NULL, otherwise, delete all entries and
193  * return the pointer to the first entry.  The order of entries
194  * deleted is from the newest to the oldest added one.
195  */
196 static inline struct llist_node *llist_del_all(struct llist_head *head)
197 {
198         return xchg(&head->first, NULL);
199 }
200 
201 extern struct llist_node *llist_del_first(struct llist_head *head);
202 
203 struct llist_node *llist_reverse_order(struct llist_node *head);
204 
205 #endif /* LLIST_H */
206 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp