/* * include/common/mini-clist.h * Circular list manipulation macros and structures. * * Copyright (C) 2002-2014 Willy Tarreau - w@1wt.eu * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation, version 2.1 * exclusively. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef _COMMON_MINI_CLIST_H #define _COMMON_MINI_CLIST_H #include /* these are circular or bidirectionnal lists only. Each list pointer points to * another list pointer in a structure, and not the structure itself. The * pointer to the next element MUST be the first one so that the list is easily * cast as a single linked list or pointer. */ struct list { struct list *n; /* next */ struct list *p; /* prev */ }; /* a back-ref is a pointer to a target list entry. It is used to detect when an * element being deleted is currently being tracked by another user. The best * example is a user dumping the session table. The table does not fit in the * output buffer so we have to set a mark on a session and go on later. But if * that marked session gets deleted, we don't want the user's pointer to go in * the wild. So we can simply link this user's request to the list of this * session's users, and put a pointer to the list element in ref, that will be * used as the mark for next iteration. */ struct bref { struct list users; struct list *ref; /* pointer to the target's list entry */ }; /* a word list is a generic list with a pointer to a string in each element. */ struct wordlist { struct list list; char *s; }; /* this is the same as above with an additional pointer to a condition. */ struct cond_wordlist { struct list list; void *cond; char *s; }; /* First undefine some macros which happen to also be defined on OpenBSD, * in sys/queue.h, used by sys/event.h */ #undef LIST_HEAD #undef LIST_INIT #undef LIST_NEXT /* ILH = Initialized List Head : used to prevent gcc from moving an empty * list to BSS. Some older version tend to trim all the array and cause * corruption. */ #define ILH { .n = (struct list *)1, .p = (struct list *)2 } #define LIST_HEAD(a) ((void *)(&(a))) #define LIST_INIT(l) ((l)->n = (l)->p = (l)) #define LIST_HEAD_INIT(l) { &l, &l } /* adds an element at the beginning of a list ; returns the element */ #define LIST_ADD(lh, el) ({ (el)->n = (lh)->n; (el)->n->p = (lh)->n = (el); (el)->p = (lh); (el); }) /* adds an element at the end of a list ; returns the element */ #define LIST_ADDQ(lh, el) ({ (el)->p = (lh)->p; (el)->p->n = (lh)->p = (el); (el)->n = (lh); (el); }) /* removes an element from a list and returns it */ #define LIST_DEL(el) ({ typeof(el) __ret = (el); (el)->n->p = (el)->p; (el)->p->n = (el)->n; (__ret); }) /* returns a pointer of type to a structure containing a list head called * at address . Note that can be the result of a function or macro * since it's used only once. * Example: LIST_ELEM(cur_node->args.next, struct node *, args) */ #define LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el))) /* checks if the list head is empty or not */ #define LIST_ISEMPTY(lh) ((lh)->n == (lh)) /* returns a pointer of type to a structure following the element * which contains list head , which is known as element in * struct pt. * Example: LIST_NEXT(args, struct node *, list) */ #define LIST_NEXT(lh, pt, el) (LIST_ELEM((lh)->n, pt, el)) /* returns a pointer of type to a structure preceding the element * which contains list head , which is known as element in * struct pt. */ #undef LIST_PREV #define LIST_PREV(lh, pt, el) (LIST_ELEM((lh)->p, pt, el)) /* * Simpler FOREACH_ITEM macro inspired from Linux sources. * Iterates through a list of items of type "typeof(*item)" which are * linked via a "struct list" member named . A pointer to the head of * the list is passed in . No temporary variable is needed. Note * that must not be modified during the loop. * Example: list_for_each_entry(cur_acl, known_acl, list) { ... }; */ #define list_for_each_entry(item, list_head, member) \ for (item = LIST_ELEM((list_head)->n, typeof(item), member); \ &item->member != (list_head); \ item = LIST_ELEM(item->member.n, typeof(item), member)) /* * Same as list_for_each_entry but starting from current point * Iterates through the list starting from * It's basically the same macro but without initializing item to the head of * the list. */ #define list_for_each_entry_from(item, list_head, member) \ for ( ; &item->member != (list_head); \ item = LIST_ELEM(item->member.n, typeof(item), member)) /* * Simpler FOREACH_ITEM_SAFE macro inspired from Linux sources. * Iterates through a list of items of type "typeof(*item)" which are * linked via a "struct list" member named . A pointer to the head of * the list is passed in . A temporary variable of same type * as is needed so that may safely be deleted if needed. * Example: list_for_each_entry_safe(cur_acl, tmp, known_acl, list) { ... }; */ #define list_for_each_entry_safe(item, back, list_head, member) \ for (item = LIST_ELEM((list_head)->n, typeof(item), member), \ back = LIST_ELEM(item->member.n, typeof(item), member); \ &item->member != (list_head); \ item = back, back = LIST_ELEM(back->member.n, typeof(back), member)) /* * Same as list_for_each_entry_safe but starting from current point * Iterates through the list starting from * It's basically the same macro but without initializing item to the head of * the list. */ #define list_for_each_entry_safe_from(item, back, list_head, member) \ for (back = LIST_ELEM(item->member.n, typeof(item), member); \ &item->member != (list_head); \ item = back, back = LIST_ELEM(back->member.n, typeof(back), member)) #include #define LLIST_BUSY ((struct list *)1) /* * Locked version of list manipulation macros. * It is OK to use those concurrently from multiple threads, as long as the * list is only used with the locked variants. The only "unlocked" macro you * can use with a locked list is LIST_INIT. */ #define LIST_ADD_LOCKED(lh, el) \ do { \ while (1) { \ struct list *n; \ struct list *p; \ n = HA_ATOMIC_XCHG(&(lh)->n, LLIST_BUSY); \ if (n == LLIST_BUSY) \ continue; \ __ha_barrier_store(); \ p = HA_ATOMIC_XCHG(&n->p, LLIST_BUSY); \ if (p == LLIST_BUSY) { \ (lh)->n = n; \ __ha_barrier_store(); \ continue; \ } \ (el)->n = n; \ (el)->p = p; \ __ha_barrier_store(); \ n->p = (el); \ __ha_barrier_store(); \ p->n = (el); \ __ha_barrier_store(); \ break; \ } \ } while (0) #define LIST_ADDQ_LOCKED(lh, el) \ do { \ while (1) { \ struct list *n; \ struct list *p; \ p = HA_ATOMIC_XCHG(&(lh)->p, LLIST_BUSY); \ if (p == LLIST_BUSY) \ continue; \ __ha_barrier_store(); \ n = HA_ATOMIC_XCHG(&p->n, LLIST_BUSY); \ if (n == LLIST_BUSY) { \ (lh)->p = p; \ __ha_barrier_store(); \ continue; \ } \ (el)->n = n; \ (el)->p = p; \ __ha_barrier_store(); \ p->n = (el); \ __ha_barrier_store(); \ n->p = (el); \ __ha_barrier_store(); \ break; \ } \ } while (0) #define LIST_DEL_LOCKED(el) \ do { \ while (1) { \ struct list *n, *n2; \ struct list *p, *p2 = NULL; \ n = HA_ATOMIC_XCHG(&(el)->n, LLIST_BUSY); \ if (n == LLIST_BUSY) \ continue; \ p = HA_ATOMIC_XCHG(&(el)->p, LLIST_BUSY); \ if (p == LLIST_BUSY) { \ (el)->n = n; \ __ha_barrier_store(); \ continue; \ } \ if (p != (el)) { \ p2 = HA_ATOMIC_XCHG(&p->n, LLIST_BUSY); \ if (p2 == LLIST_BUSY) { \ (el)->p = p; \ (el)->n = n; \ __ha_barrier_store(); \ continue; \ } \ } \ if (n != (el)) { \ n2 = HA_ATOMIC_XCHG(&n->p, LLIST_BUSY); \ if (n2 == LLIST_BUSY) { \ if (p2 != NULL) \ p2->n = (el); \ (el)->p = p; \ (el)->n = n; \ __ha_barrier_store(); \ continue; \ } \ } \ n->p = p; \ p->n = n; \ __ha_barrier_store(); \ (el)->p = (el); \ (el)->n = (el); \ __ha_barrier_store(); \ break; \ } \ } while (0) /* Remove the first element from the list, and return it */ #define LIST_POP_LOCKED(lh, pt, el) \ ({ \ void *_ret; \ while (1) { \ struct list *n, *n2; \ struct list *p, *p2; \ n = HA_ATOMIC_XCHG(&(lh)->n, LLIST_BUSY); \ if (n == LLIST_BUSY) \ continue; \ if (n == (lh)) { \ (lh)->n = lh; \ __ha_barrier_store(); \ _ret = NULL; \ break; \ } \ p = HA_ATOMIC_XCHG(&n->p, LLIST_BUSY); \ if (p == LLIST_BUSY) { \ (lh)->n = n; \ __ha_barrier_store(); \ continue; \ } \ n2 = HA_ATOMIC_XCHG(&n->n, LLIST_BUSY); \ if (n2 == LLIST_BUSY) { \ n->p = p; \ __ha_barrier_store(); \ (lh)->n = n; \ __ha_barrier_store(); \ continue; \ } \ p2 = HA_ATOMIC_XCHG(&n2->p, LLIST_BUSY); \ if (p2 == LLIST_BUSY) { \ n->n = n2; \ n->p = p; \ __ha_barrier_store(); \ (lh)->n = n; \ __ha_barrier_store(); \ continue; \ } \ (lh)->n = n2; \ (n2)->p = (lh); \ __ha_barrier_store(); \ (n)->p = (n); \ (n)->n = (n); \ __ha_barrier_store(); \ _ret = LIST_ELEM(n, pt, el); \ break; \ } \ (_ret); \ }) #endif /* _COMMON_MINI_CLIST_H */