Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 1 | #ifndef _LINUX_RCULIST_H |
| 2 | #define _LINUX_RCULIST_H |
| 3 | |
| 4 | #ifdef __KERNEL__ |
| 5 | |
| 6 | /* |
| 7 | * RCU-protected list version |
| 8 | */ |
| 9 | #include <linux/list.h> |
Franck Bui-Huu | 10aa9d2 | 2008-05-12 21:21:06 +0200 | [diff] [blame] | 10 | #include <linux/rcupdate.h> |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 11 | |
| 12 | /* |
Paul E. McKenney | 65e6bf4 | 2010-08-19 21:43:09 -0700 | [diff] [blame] | 13 | * Why is there no list_empty_rcu()? Because list_empty() serves this |
| 14 | * purpose. The list_empty() function fetches the RCU-protected pointer |
| 15 | * and compares it to the address of the list head, but neither dereferences |
| 16 | * this pointer itself nor provides this pointer to the caller. Therefore, |
| 17 | * it is not necessary to use rcu_dereference(), so that list_empty() can |
| 18 | * be used anywhere you would want to use a list_empty_rcu(). |
| 19 | */ |
| 20 | |
| 21 | /* |
Paul E. McKenney | 2a855b6 | 2013-08-23 09:40:42 -0700 | [diff] [blame] | 22 | * INIT_LIST_HEAD_RCU - Initialize a list_head visible to RCU readers |
| 23 | * @list: list to be initialized |
| 24 | * |
| 25 | * You should instead use INIT_LIST_HEAD() for normal initialization and |
| 26 | * cleanup tasks, when readers have no access to the list being initialized. |
| 27 | * However, if the list being initialized is visible to readers, you |
| 28 | * need to keep the compiler from being too mischievous. |
| 29 | */ |
| 30 | static inline void INIT_LIST_HEAD_RCU(struct list_head *list) |
| 31 | { |
Paul E. McKenney | 7d0ae80 | 2015-03-03 14:57:58 -0800 | [diff] [blame] | 32 | WRITE_ONCE(list->next, list); |
| 33 | WRITE_ONCE(list->prev, list); |
Paul E. McKenney | 2a855b6 | 2013-08-23 09:40:42 -0700 | [diff] [blame] | 34 | } |
| 35 | |
| 36 | /* |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 37 | * return the ->next pointer of a list_head in an rcu safe |
| 38 | * way, we must not access it directly |
| 39 | */ |
| 40 | #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) |
| 41 | |
| 42 | /* |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 43 | * Insert a new entry between two known consecutive entries. |
| 44 | * |
| 45 | * This is only for internal list manipulation where we know |
| 46 | * the prev/next entries already! |
| 47 | */ |
Dave Jones | 559f9ba | 2012-03-14 22:17:39 -0400 | [diff] [blame] | 48 | #ifndef CONFIG_DEBUG_LIST |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 49 | static inline void __list_add_rcu(struct list_head *new, |
| 50 | struct list_head *prev, struct list_head *next) |
| 51 | { |
| 52 | new->next = next; |
| 53 | new->prev = prev; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 54 | rcu_assign_pointer(list_next_rcu(prev), new); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 55 | next->prev = new; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 56 | } |
Dave Jones | 559f9ba | 2012-03-14 22:17:39 -0400 | [diff] [blame] | 57 | #else |
Teodora Baluta | 584dc4c | 2013-11-11 17:11:23 +0200 | [diff] [blame] | 58 | void __list_add_rcu(struct list_head *new, |
| 59 | struct list_head *prev, struct list_head *next); |
Dave Jones | 559f9ba | 2012-03-14 22:17:39 -0400 | [diff] [blame] | 60 | #endif |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 61 | |
| 62 | /** |
| 63 | * list_add_rcu - add a new entry to rcu-protected list |
| 64 | * @new: new entry to be added |
| 65 | * @head: list head to add it after |
| 66 | * |
| 67 | * Insert a new entry after the specified head. |
| 68 | * This is good for implementing stacks. |
| 69 | * |
| 70 | * The caller must take whatever precautions are necessary |
| 71 | * (such as holding appropriate locks) to avoid racing |
| 72 | * with another list-mutation primitive, such as list_add_rcu() |
| 73 | * or list_del_rcu(), running on this same list. |
| 74 | * However, it is perfectly legal to run concurrently with |
| 75 | * the _rcu list-traversal primitives, such as |
| 76 | * list_for_each_entry_rcu(). |
| 77 | */ |
| 78 | static inline void list_add_rcu(struct list_head *new, struct list_head *head) |
| 79 | { |
| 80 | __list_add_rcu(new, head, head->next); |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * list_add_tail_rcu - add a new entry to rcu-protected list |
| 85 | * @new: new entry to be added |
| 86 | * @head: list head to add it before |
| 87 | * |
| 88 | * Insert a new entry before the specified head. |
| 89 | * This is useful for implementing queues. |
| 90 | * |
| 91 | * The caller must take whatever precautions are necessary |
| 92 | * (such as holding appropriate locks) to avoid racing |
| 93 | * with another list-mutation primitive, such as list_add_tail_rcu() |
| 94 | * or list_del_rcu(), running on this same list. |
| 95 | * However, it is perfectly legal to run concurrently with |
| 96 | * the _rcu list-traversal primitives, such as |
| 97 | * list_for_each_entry_rcu(). |
| 98 | */ |
| 99 | static inline void list_add_tail_rcu(struct list_head *new, |
| 100 | struct list_head *head) |
| 101 | { |
| 102 | __list_add_rcu(new, head->prev, head); |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * list_del_rcu - deletes entry from list without re-initialization |
| 107 | * @entry: the element to delete from the list. |
| 108 | * |
| 109 | * Note: list_empty() on entry does not return true after this, |
| 110 | * the entry is in an undefined state. It is useful for RCU based |
| 111 | * lockfree traversal. |
| 112 | * |
| 113 | * In particular, it means that we can not poison the forward |
| 114 | * pointers that may still be used for walking the list. |
| 115 | * |
| 116 | * The caller must take whatever precautions are necessary |
| 117 | * (such as holding appropriate locks) to avoid racing |
| 118 | * with another list-mutation primitive, such as list_del_rcu() |
| 119 | * or list_add_rcu(), running on this same list. |
| 120 | * However, it is perfectly legal to run concurrently with |
| 121 | * the _rcu list-traversal primitives, such as |
| 122 | * list_for_each_entry_rcu(). |
| 123 | * |
| 124 | * Note that the caller is not permitted to immediately free |
| 125 | * the newly deleted entry. Instead, either synchronize_rcu() |
| 126 | * or call_rcu() must be used to defer freeing until an RCU |
| 127 | * grace period has elapsed. |
| 128 | */ |
| 129 | static inline void list_del_rcu(struct list_head *entry) |
| 130 | { |
Dave Jones | 559f9ba | 2012-03-14 22:17:39 -0400 | [diff] [blame] | 131 | __list_del_entry(entry); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 132 | entry->prev = LIST_POISON2; |
| 133 | } |
| 134 | |
| 135 | /** |
Andrea Arcangeli | 6beeac7 | 2008-07-28 15:46:22 -0700 | [diff] [blame] | 136 | * hlist_del_init_rcu - deletes entry from hash list with re-initialization |
| 137 | * @n: the element to delete from the hash list. |
| 138 | * |
| 139 | * Note: list_unhashed() on the node return true after this. It is |
| 140 | * useful for RCU based read lockfree traversal if the writer side |
| 141 | * must know if the list entry is still hashed or already unhashed. |
| 142 | * |
| 143 | * In particular, it means that we can not poison the forward pointers |
| 144 | * that may still be used for walking the hash list and we can only |
| 145 | * zero the pprev pointer so list_unhashed() will return true after |
| 146 | * this. |
| 147 | * |
| 148 | * The caller must take whatever precautions are necessary (such as |
| 149 | * holding appropriate locks) to avoid racing with another |
| 150 | * list-mutation primitive, such as hlist_add_head_rcu() or |
| 151 | * hlist_del_rcu(), running on this same list. However, it is |
| 152 | * perfectly legal to run concurrently with the _rcu list-traversal |
| 153 | * primitives, such as hlist_for_each_entry_rcu(). |
| 154 | */ |
| 155 | static inline void hlist_del_init_rcu(struct hlist_node *n) |
| 156 | { |
| 157 | if (!hlist_unhashed(n)) { |
| 158 | __hlist_del(n); |
| 159 | n->pprev = NULL; |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | /** |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 164 | * list_replace_rcu - replace old entry by new one |
| 165 | * @old : the element to be replaced |
| 166 | * @new : the new element to insert |
| 167 | * |
| 168 | * The @old entry will be replaced with the @new entry atomically. |
| 169 | * Note: @old should not be empty. |
| 170 | */ |
| 171 | static inline void list_replace_rcu(struct list_head *old, |
| 172 | struct list_head *new) |
| 173 | { |
| 174 | new->next = old->next; |
| 175 | new->prev = old->prev; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 176 | rcu_assign_pointer(list_next_rcu(new->prev), new); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 177 | new->next->prev = new; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 178 | old->prev = LIST_POISON2; |
| 179 | } |
| 180 | |
| 181 | /** |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 182 | * __list_splice_init_rcu - join an RCU-protected list into an existing list. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 183 | * @list: the RCU-protected list to splice |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 184 | * @prev: points to the last element of the existing list |
| 185 | * @next: points to the first element of the existing list |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 186 | * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... |
| 187 | * |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 188 | * The list pointed to by @prev and @next can be RCU-read traversed |
| 189 | * concurrently with this function. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 190 | * |
| 191 | * Note that this function blocks. |
| 192 | * |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 193 | * Important note: the caller must take whatever action is necessary to prevent |
| 194 | * any other updates to the existing list. In principle, it is possible to |
| 195 | * modify the list as soon as sync() begins execution. If this sort of thing |
| 196 | * becomes necessary, an alternative version based on call_rcu() could be |
| 197 | * created. But only if -really- needed -- there is no shortage of RCU API |
| 198 | * members. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 199 | */ |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 200 | static inline void __list_splice_init_rcu(struct list_head *list, |
| 201 | struct list_head *prev, |
| 202 | struct list_head *next, |
| 203 | void (*sync)(void)) |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 204 | { |
| 205 | struct list_head *first = list->next; |
| 206 | struct list_head *last = list->prev; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 207 | |
Paul E. McKenney | 2a855b6 | 2013-08-23 09:40:42 -0700 | [diff] [blame] | 208 | /* |
| 209 | * "first" and "last" tracking list, so initialize it. RCU readers |
| 210 | * have access to this list, so we must use INIT_LIST_HEAD_RCU() |
| 211 | * instead of INIT_LIST_HEAD(). |
| 212 | */ |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 213 | |
Paul E. McKenney | 2a855b6 | 2013-08-23 09:40:42 -0700 | [diff] [blame] | 214 | INIT_LIST_HEAD_RCU(list); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 215 | |
| 216 | /* |
| 217 | * At this point, the list body still points to the source list. |
| 218 | * Wait for any readers to finish using the list before splicing |
| 219 | * the list body into the new list. Any new readers will see |
| 220 | * an empty list. |
| 221 | */ |
| 222 | |
| 223 | sync(); |
| 224 | |
| 225 | /* |
| 226 | * Readers are finished with the source list, so perform splice. |
| 227 | * The order is important if the new list is global and accessible |
| 228 | * to concurrent RCU readers. Note that RCU readers are not |
| 229 | * permitted to traverse the prev pointers without excluding |
| 230 | * this function. |
| 231 | */ |
| 232 | |
Petko Manolov | 7d86dcc | 2015-10-12 18:23:51 +0300 | [diff] [blame] | 233 | last->next = next; |
| 234 | rcu_assign_pointer(list_next_rcu(prev), first); |
| 235 | first->prev = prev; |
| 236 | next->prev = last; |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * list_splice_init_rcu - splice an RCU-protected list into an existing list, |
| 241 | * designed for stacks. |
| 242 | * @list: the RCU-protected list to splice |
| 243 | * @head: the place in the existing list to splice the first list into |
| 244 | * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... |
| 245 | */ |
| 246 | static inline void list_splice_init_rcu(struct list_head *list, |
| 247 | struct list_head *head, |
| 248 | void (*sync)(void)) |
| 249 | { |
| 250 | if (!list_empty(list)) |
| 251 | __list_splice_init_rcu(list, head, head->next, sync); |
| 252 | } |
| 253 | |
| 254 | /** |
| 255 | * list_splice_tail_init_rcu - splice an RCU-protected list into an existing |
| 256 | * list, designed for queues. |
| 257 | * @list: the RCU-protected list to splice |
| 258 | * @head: the place in the existing list to splice the first list into |
| 259 | * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... |
| 260 | */ |
| 261 | static inline void list_splice_tail_init_rcu(struct list_head *list, |
| 262 | struct list_head *head, |
| 263 | void (*sync)(void)) |
| 264 | { |
| 265 | if (!list_empty(list)) |
| 266 | __list_splice_init_rcu(list, head->prev, head, sync); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 267 | } |
| 268 | |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 269 | /** |
| 270 | * list_entry_rcu - get the struct for this entry |
| 271 | * @ptr: the &struct list_head pointer. |
| 272 | * @type: the type of the struct this is embedded in. |
Andrey Utkin | 3943f42 | 2014-11-14 05:09:55 +0400 | [diff] [blame] | 273 | * @member: the name of the list_head within the struct. |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 274 | * |
| 275 | * This primitive may safely run concurrently with the _rcu list-mutation |
| 276 | * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| 277 | */ |
| 278 | #define list_entry_rcu(ptr, type, member) \ |
Patrick Marlier | 8db70b1 | 2015-09-11 15:50:35 -0700 | [diff] [blame] | 279 | container_of(lockless_dereference(ptr), type, member) |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 280 | |
| 281 | /** |
Michel Machado | f88022a | 2012-04-10 14:07:40 -0400 | [diff] [blame] | 282 | * Where are list_empty_rcu() and list_first_entry_rcu()? |
| 283 | * |
| 284 | * Implementing those functions following their counterparts list_empty() and |
| 285 | * list_first_entry() is not advisable because they lead to subtle race |
| 286 | * conditions as the following snippet shows: |
| 287 | * |
| 288 | * if (!list_empty_rcu(mylist)) { |
| 289 | * struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member); |
| 290 | * do_something(bar); |
| 291 | * } |
| 292 | * |
| 293 | * The list may not be empty when list_empty_rcu checks it, but it may be when |
| 294 | * list_first_entry_rcu rereads the ->next pointer. |
| 295 | * |
| 296 | * Rereading the ->next pointer is not a problem for list_empty() and |
| 297 | * list_first_entry() because they would be protected by a lock that blocks |
| 298 | * writers. |
| 299 | * |
| 300 | * See list_first_or_null_rcu for an alternative. |
| 301 | */ |
| 302 | |
| 303 | /** |
| 304 | * list_first_or_null_rcu - get the first element from a list |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 305 | * @ptr: the list head to take the element from. |
| 306 | * @type: the type of the struct this is embedded in. |
Andrey Utkin | 3943f42 | 2014-11-14 05:09:55 +0400 | [diff] [blame] | 307 | * @member: the name of the list_head within the struct. |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 308 | * |
Michel Machado | f88022a | 2012-04-10 14:07:40 -0400 | [diff] [blame] | 309 | * Note that if the list is empty, it returns NULL. |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 310 | * |
| 311 | * This primitive may safely run concurrently with the _rcu list-mutation |
| 312 | * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| 313 | */ |
Michel Machado | f88022a | 2012-04-10 14:07:40 -0400 | [diff] [blame] | 314 | #define list_first_or_null_rcu(ptr, type, member) \ |
Joe Perches | 0adab9b | 2013-12-05 16:19:15 -0800 | [diff] [blame] | 315 | ({ \ |
| 316 | struct list_head *__ptr = (ptr); \ |
Paul E. McKenney | 7d0ae80 | 2015-03-03 14:57:58 -0800 | [diff] [blame] | 317 | struct list_head *__next = READ_ONCE(__ptr->next); \ |
Joe Perches | 0adab9b | 2013-12-05 16:19:15 -0800 | [diff] [blame] | 318 | likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \ |
| 319 | }) |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 320 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 321 | /** |
Tom Herbert | ff3c44e | 2016-03-07 14:11:00 -0800 | [diff] [blame] | 322 | * list_next_or_null_rcu - get the first element from a list |
| 323 | * @head: the head for the list. |
| 324 | * @ptr: the list head to take the next element from. |
| 325 | * @type: the type of the struct this is embedded in. |
| 326 | * @member: the name of the list_head within the struct. |
| 327 | * |
| 328 | * Note that if the ptr is at the end of the list, NULL is returned. |
| 329 | * |
| 330 | * This primitive may safely run concurrently with the _rcu list-mutation |
| 331 | * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). |
| 332 | */ |
| 333 | #define list_next_or_null_rcu(head, ptr, type, member) \ |
| 334 | ({ \ |
| 335 | struct list_head *__head = (head); \ |
| 336 | struct list_head *__ptr = (ptr); \ |
| 337 | struct list_head *__next = READ_ONCE(__ptr->next); \ |
| 338 | likely(__next != __head) ? list_entry_rcu(__next, type, \ |
| 339 | member) : NULL; \ |
| 340 | }) |
| 341 | |
| 342 | /** |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 343 | * list_for_each_entry_rcu - iterate over rcu list of given type |
| 344 | * @pos: the type * to use as a loop cursor. |
| 345 | * @head: the head for your list. |
Andrey Utkin | 3943f42 | 2014-11-14 05:09:55 +0400 | [diff] [blame] | 346 | * @member: the name of the list_head within the struct. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 347 | * |
| 348 | * This list-traversal primitive may safely run concurrently with |
| 349 | * the _rcu list-mutation primitives such as list_add_rcu() |
| 350 | * as long as the traversal is guarded by rcu_read_lock(). |
| 351 | */ |
| 352 | #define list_for_each_entry_rcu(pos, head, member) \ |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 353 | for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ |
Linus Torvalds | e66eed6 | 2011-05-19 14:15:29 -0700 | [diff] [blame] | 354 | &pos->member != (head); \ |
Jiri Pirko | 72c6a98 | 2009-04-14 17:33:57 +0200 | [diff] [blame] | 355 | pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 356 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 357 | /** |
Alexey Kardashevskiy | 69b9072 | 2015-12-05 18:14:19 -0800 | [diff] [blame] | 358 | * list_entry_lockless - get the struct for this entry |
| 359 | * @ptr: the &struct list_head pointer. |
| 360 | * @type: the type of the struct this is embedded in. |
| 361 | * @member: the name of the list_head within the struct. |
| 362 | * |
| 363 | * This primitive may safely run concurrently with the _rcu list-mutation |
| 364 | * primitives such as list_add_rcu(), but requires some implicit RCU |
| 365 | * read-side guarding. One example is running within a special |
| 366 | * exception-time environment where preemption is disabled and where |
| 367 | * lockdep cannot be invoked (in which case updaters must use RCU-sched, |
| 368 | * as in synchronize_sched(), call_rcu_sched(), and friends). Another |
| 369 | * example is when items are added to the list, but never deleted. |
| 370 | */ |
| 371 | #define list_entry_lockless(ptr, type, member) \ |
| 372 | container_of((typeof(ptr))lockless_dereference(ptr), type, member) |
| 373 | |
| 374 | /** |
| 375 | * list_for_each_entry_lockless - iterate over rcu list of given type |
| 376 | * @pos: the type * to use as a loop cursor. |
| 377 | * @head: the head for your list. |
| 378 | * @member: the name of the list_struct within the struct. |
| 379 | * |
| 380 | * This primitive may safely run concurrently with the _rcu list-mutation |
| 381 | * primitives such as list_add_rcu(), but requires some implicit RCU |
| 382 | * read-side guarding. One example is running within a special |
| 383 | * exception-time environment where preemption is disabled and where |
| 384 | * lockdep cannot be invoked (in which case updaters must use RCU-sched, |
| 385 | * as in synchronize_sched(), call_rcu_sched(), and friends). Another |
| 386 | * example is when items are added to the list, but never deleted. |
| 387 | */ |
| 388 | #define list_for_each_entry_lockless(pos, head, member) \ |
| 389 | for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \ |
| 390 | &pos->member != (head); \ |
| 391 | pos = list_entry_lockless(pos->member.next, typeof(*pos), member)) |
| 392 | |
| 393 | /** |
stephen hemminger | 254245d | 2009-11-10 07:54:47 +0000 | [diff] [blame] | 394 | * list_for_each_entry_continue_rcu - continue iteration over list of given type |
| 395 | * @pos: the type * to use as a loop cursor. |
| 396 | * @head: the head for your list. |
Andrey Utkin | 3943f42 | 2014-11-14 05:09:55 +0400 | [diff] [blame] | 397 | * @member: the name of the list_head within the struct. |
stephen hemminger | 254245d | 2009-11-10 07:54:47 +0000 | [diff] [blame] | 398 | * |
| 399 | * Continue to iterate over list of given type, continuing after |
| 400 | * the current position. |
| 401 | */ |
| 402 | #define list_for_each_entry_continue_rcu(pos, head, member) \ |
| 403 | for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \ |
Linus Torvalds | e66eed6 | 2011-05-19 14:15:29 -0700 | [diff] [blame] | 404 | &pos->member != (head); \ |
stephen hemminger | 254245d | 2009-11-10 07:54:47 +0000 | [diff] [blame] | 405 | pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) |
| 406 | |
| 407 | /** |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 408 | * hlist_del_rcu - deletes entry from hash list without re-initialization |
| 409 | * @n: the element to delete from the hash list. |
| 410 | * |
| 411 | * Note: list_unhashed() on entry does not return true after this, |
| 412 | * the entry is in an undefined state. It is useful for RCU based |
| 413 | * lockfree traversal. |
| 414 | * |
| 415 | * In particular, it means that we can not poison the forward |
| 416 | * pointers that may still be used for walking the hash list. |
| 417 | * |
| 418 | * The caller must take whatever precautions are necessary |
| 419 | * (such as holding appropriate locks) to avoid racing |
| 420 | * with another list-mutation primitive, such as hlist_add_head_rcu() |
| 421 | * or hlist_del_rcu(), running on this same list. |
| 422 | * However, it is perfectly legal to run concurrently with |
| 423 | * the _rcu list-traversal primitives, such as |
| 424 | * hlist_for_each_entry(). |
| 425 | */ |
| 426 | static inline void hlist_del_rcu(struct hlist_node *n) |
| 427 | { |
| 428 | __hlist_del(n); |
| 429 | n->pprev = LIST_POISON2; |
| 430 | } |
| 431 | |
| 432 | /** |
| 433 | * hlist_replace_rcu - replace old entry by new one |
| 434 | * @old : the element to be replaced |
| 435 | * @new : the new element to insert |
| 436 | * |
| 437 | * The @old entry will be replaced with the @new entry atomically. |
| 438 | */ |
| 439 | static inline void hlist_replace_rcu(struct hlist_node *old, |
| 440 | struct hlist_node *new) |
| 441 | { |
| 442 | struct hlist_node *next = old->next; |
| 443 | |
| 444 | new->next = next; |
| 445 | new->pprev = old->pprev; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 446 | rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 447 | if (next) |
| 448 | new->next->pprev = &new->next; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 449 | old->pprev = LIST_POISON2; |
| 450 | } |
| 451 | |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 452 | /* |
| 453 | * return the first or the next element in an RCU protected hlist |
| 454 | */ |
| 455 | #define hlist_first_rcu(head) (*((struct hlist_node __rcu **)(&(head)->first))) |
| 456 | #define hlist_next_rcu(node) (*((struct hlist_node __rcu **)(&(node)->next))) |
| 457 | #define hlist_pprev_rcu(node) (*((struct hlist_node __rcu **)((node)->pprev))) |
| 458 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 459 | /** |
| 460 | * hlist_add_head_rcu |
| 461 | * @n: the element to add to the hash list. |
| 462 | * @h: the list to add to. |
| 463 | * |
| 464 | * Description: |
| 465 | * Adds the specified element to the specified hlist, |
| 466 | * while permitting racing traversals. |
| 467 | * |
| 468 | * The caller must take whatever precautions are necessary |
| 469 | * (such as holding appropriate locks) to avoid racing |
| 470 | * with another list-mutation primitive, such as hlist_add_head_rcu() |
| 471 | * or hlist_del_rcu(), running on this same list. |
| 472 | * However, it is perfectly legal to run concurrently with |
| 473 | * the _rcu list-traversal primitives, such as |
| 474 | * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| 475 | * problems on Alpha CPUs. Regardless of the type of CPU, the |
| 476 | * list-traversal primitive must be guarded by rcu_read_lock(). |
| 477 | */ |
| 478 | static inline void hlist_add_head_rcu(struct hlist_node *n, |
| 479 | struct hlist_head *h) |
| 480 | { |
| 481 | struct hlist_node *first = h->first; |
Franck Bui-Huu | 10aa9d2 | 2008-05-12 21:21:06 +0200 | [diff] [blame] | 482 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 483 | n->next = first; |
| 484 | n->pprev = &h->first; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 485 | rcu_assign_pointer(hlist_first_rcu(h), n); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 486 | if (first) |
| 487 | first->pprev = &n->next; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 488 | } |
| 489 | |
| 490 | /** |
David S. Miller | 1602f49 | 2016-04-23 18:26:24 -0400 | [diff] [blame] | 491 | * hlist_add_tail_rcu |
| 492 | * @n: the element to add to the hash list. |
| 493 | * @h: the list to add to. |
| 494 | * |
| 495 | * Description: |
| 496 | * Adds the specified element to the specified hlist, |
| 497 | * while permitting racing traversals. |
| 498 | * |
| 499 | * The caller must take whatever precautions are necessary |
| 500 | * (such as holding appropriate locks) to avoid racing |
| 501 | * with another list-mutation primitive, such as hlist_add_head_rcu() |
| 502 | * or hlist_del_rcu(), running on this same list. |
| 503 | * However, it is perfectly legal to run concurrently with |
| 504 | * the _rcu list-traversal primitives, such as |
| 505 | * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| 506 | * problems on Alpha CPUs. Regardless of the type of CPU, the |
| 507 | * list-traversal primitive must be guarded by rcu_read_lock(). |
| 508 | */ |
| 509 | static inline void hlist_add_tail_rcu(struct hlist_node *n, |
| 510 | struct hlist_head *h) |
| 511 | { |
| 512 | struct hlist_node *i, *last = NULL; |
| 513 | |
| 514 | for (i = hlist_first_rcu(h); i; i = hlist_next_rcu(i)) |
| 515 | last = i; |
| 516 | |
| 517 | if (last) { |
| 518 | n->next = last->next; |
| 519 | n->pprev = &last->next; |
| 520 | rcu_assign_pointer(hlist_next_rcu(last), n); |
| 521 | } else { |
| 522 | hlist_add_head_rcu(n, h); |
| 523 | } |
| 524 | } |
| 525 | |
| 526 | /** |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 527 | * hlist_add_before_rcu |
| 528 | * @n: the new element to add to the hash list. |
| 529 | * @next: the existing element to add the new element before. |
| 530 | * |
| 531 | * Description: |
| 532 | * Adds the specified element to the specified hlist |
| 533 | * before the specified node while permitting racing traversals. |
| 534 | * |
| 535 | * The caller must take whatever precautions are necessary |
| 536 | * (such as holding appropriate locks) to avoid racing |
| 537 | * with another list-mutation primitive, such as hlist_add_head_rcu() |
| 538 | * or hlist_del_rcu(), running on this same list. |
| 539 | * However, it is perfectly legal to run concurrently with |
| 540 | * the _rcu list-traversal primitives, such as |
| 541 | * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| 542 | * problems on Alpha CPUs. |
| 543 | */ |
| 544 | static inline void hlist_add_before_rcu(struct hlist_node *n, |
| 545 | struct hlist_node *next) |
| 546 | { |
| 547 | n->pprev = next->pprev; |
| 548 | n->next = next; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 549 | rcu_assign_pointer(hlist_pprev_rcu(n), n); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 550 | next->pprev = &n->next; |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 551 | } |
| 552 | |
| 553 | /** |
Ken Helias | 1d02328 | 2014-08-06 16:09:16 -0700 | [diff] [blame] | 554 | * hlist_add_behind_rcu |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 555 | * @n: the new element to add to the hash list. |
Ken Helias | 1d02328 | 2014-08-06 16:09:16 -0700 | [diff] [blame] | 556 | * @prev: the existing element to add the new element after. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 557 | * |
| 558 | * Description: |
| 559 | * Adds the specified element to the specified hlist |
| 560 | * after the specified node while permitting racing traversals. |
| 561 | * |
| 562 | * The caller must take whatever precautions are necessary |
| 563 | * (such as holding appropriate locks) to avoid racing |
| 564 | * with another list-mutation primitive, such as hlist_add_head_rcu() |
| 565 | * or hlist_del_rcu(), running on this same list. |
| 566 | * However, it is perfectly legal to run concurrently with |
| 567 | * the _rcu list-traversal primitives, such as |
| 568 | * hlist_for_each_entry_rcu(), used to prevent memory-consistency |
| 569 | * problems on Alpha CPUs. |
| 570 | */ |
Ken Helias | 1d02328 | 2014-08-06 16:09:16 -0700 | [diff] [blame] | 571 | static inline void hlist_add_behind_rcu(struct hlist_node *n, |
| 572 | struct hlist_node *prev) |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 573 | { |
| 574 | n->next = prev->next; |
| 575 | n->pprev = &prev->next; |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 576 | rcu_assign_pointer(hlist_next_rcu(prev), n); |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 577 | if (n->next) |
| 578 | n->next->pprev = &n->next; |
| 579 | } |
| 580 | |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 581 | #define __hlist_for_each_rcu(pos, head) \ |
| 582 | for (pos = rcu_dereference(hlist_first_rcu(head)); \ |
Linus Torvalds | 75d65a4 | 2011-05-19 13:50:07 -0700 | [diff] [blame] | 583 | pos; \ |
Arnd Bergmann | 67bdbff | 2010-02-25 16:55:13 +0100 | [diff] [blame] | 584 | pos = rcu_dereference(hlist_next_rcu(pos))) |
stephen hemminger | 1cc5232 | 2010-02-22 07:57:17 +0000 | [diff] [blame] | 585 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 586 | /** |
| 587 | * hlist_for_each_entry_rcu - iterate over rcu list of given type |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 588 | * @pos: the type * to use as a loop cursor. |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 589 | * @head: the head for your list. |
| 590 | * @member: the name of the hlist_node within the struct. |
| 591 | * |
| 592 | * This list-traversal primitive may safely run concurrently with |
| 593 | * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| 594 | * as long as the traversal is guarded by rcu_read_lock(). |
| 595 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 596 | #define hlist_for_each_entry_rcu(pos, head, member) \ |
| 597 | for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\ |
| 598 | typeof(*(pos)), member); \ |
| 599 | pos; \ |
| 600 | pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\ |
| 601 | &(pos)->member)), typeof(*(pos)), member)) |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 602 | |
stephen hemminger | 5c578aed | 2010-03-17 20:31:11 +0000 | [diff] [blame] | 603 | /** |
Steven Rostedt | 12bcbe6 | 2013-05-28 14:38:42 -0400 | [diff] [blame] | 604 | * hlist_for_each_entry_rcu_notrace - iterate over rcu list of given type (for tracing) |
| 605 | * @pos: the type * to use as a loop cursor. |
| 606 | * @head: the head for your list. |
| 607 | * @member: the name of the hlist_node within the struct. |
| 608 | * |
| 609 | * This list-traversal primitive may safely run concurrently with |
| 610 | * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| 611 | * as long as the traversal is guarded by rcu_read_lock(). |
| 612 | * |
| 613 | * This is the same as hlist_for_each_entry_rcu() except that it does |
| 614 | * not do any RCU debugging or tracing. |
| 615 | */ |
| 616 | #define hlist_for_each_entry_rcu_notrace(pos, head, member) \ |
| 617 | for (pos = hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\ |
| 618 | typeof(*(pos)), member); \ |
| 619 | pos; \ |
| 620 | pos = hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\ |
| 621 | &(pos)->member)), typeof(*(pos)), member)) |
| 622 | |
| 623 | /** |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 624 | * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 625 | * @pos: the type * to use as a loop cursor. |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 626 | * @head: the head for your list. |
| 627 | * @member: the name of the hlist_node within the struct. |
| 628 | * |
| 629 | * This list-traversal primitive may safely run concurrently with |
| 630 | * the _rcu list-mutation primitives such as hlist_add_head_rcu() |
| 631 | * as long as the traversal is guarded by rcu_read_lock(). |
| 632 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 633 | #define hlist_for_each_entry_rcu_bh(pos, head, member) \ |
| 634 | for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_first_rcu(head)),\ |
| 635 | typeof(*(pos)), member); \ |
| 636 | pos; \ |
| 637 | pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(\ |
| 638 | &(pos)->member)), typeof(*(pos)), member)) |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 639 | |
| 640 | /** |
stephen hemminger | 5c578aed | 2010-03-17 20:31:11 +0000 | [diff] [blame] | 641 | * hlist_for_each_entry_continue_rcu - iterate over a hlist continuing after current point |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 642 | * @pos: the type * to use as a loop cursor. |
stephen hemminger | 5c578aed | 2010-03-17 20:31:11 +0000 | [diff] [blame] | 643 | * @member: the name of the hlist_node within the struct. |
| 644 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 645 | #define hlist_for_each_entry_continue_rcu(pos, member) \ |
Ying Xue | f520c98 | 2014-12-12 09:36:14 +0800 | [diff] [blame] | 646 | for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| 647 | &(pos)->member)), typeof(*(pos)), member); \ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 648 | pos; \ |
Ying Xue | f520c98 | 2014-12-12 09:36:14 +0800 | [diff] [blame] | 649 | pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| 650 | &(pos)->member)), typeof(*(pos)), member)) |
stephen hemminger | 5c578aed | 2010-03-17 20:31:11 +0000 | [diff] [blame] | 651 | |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 652 | /** |
| 653 | * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 654 | * @pos: the type * to use as a loop cursor. |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 655 | * @member: the name of the hlist_node within the struct. |
| 656 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 657 | #define hlist_for_each_entry_continue_rcu_bh(pos, member) \ |
Ying Xue | f520c98 | 2014-12-12 09:36:14 +0800 | [diff] [blame] | 658 | for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ |
| 659 | &(pos)->member)), typeof(*(pos)), member); \ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 660 | pos; \ |
Ying Xue | f520c98 | 2014-12-12 09:36:14 +0800 | [diff] [blame] | 661 | pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ |
| 662 | &(pos)->member)), typeof(*(pos)), member)) |
Eric Dumazet | 4f70ecc | 2010-05-03 10:50:14 +0000 | [diff] [blame] | 663 | |
Ying Xue | 97ede29 | 2014-12-02 15:00:30 +0800 | [diff] [blame] | 664 | /** |
| 665 | * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point |
| 666 | * @pos: the type * to use as a loop cursor. |
| 667 | * @member: the name of the hlist_node within the struct. |
| 668 | */ |
| 669 | #define hlist_for_each_entry_from_rcu(pos, member) \ |
| 670 | for (; pos; \ |
Ying Xue | f517700 | 2015-03-26 13:27:08 +0800 | [diff] [blame] | 671 | pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ |
| 672 | &(pos)->member)), typeof(*(pos)), member)) |
stephen hemminger | 5c578aed | 2010-03-17 20:31:11 +0000 | [diff] [blame] | 673 | |
Franck Bui-Huu | 8252474 | 2008-05-12 21:21:05 +0200 | [diff] [blame] | 674 | #endif /* __KERNEL__ */ |
| 675 | #endif |