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haproxy/include/common/mini-clist.h
Olivier Houchard 9f8d821a55 MEDIUM: list: Use _HA_ATOMIC_* 
Use _HA_ATOMIC_ instead of HA_ATOMIC_ because we know we don't need barriers.
2019-03-14 15:55:15 +01:00

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/*
* 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 <common/config.h>
/* 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); })
/* removes an element from a list, initializes it and returns it.
* This is faster than LIST_DEL+LIST_INIT as we avoid reloading the pointers.
*/
#define LIST_DEL_INIT(el) ({ \
typeof(el) __ret = (el); \
typeof(__ret->n) __n = __ret->n; \
typeof(__ret->p) __p = __ret->p; \
__n->p = __p; __p->n = __n; \
__ret->n = __ret->p = __ret; \
__ret; \
})
/* returns a pointer of type <pt> to a structure containing a list head called
* <el> at address <lh>. Note that <lh> 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 <lh> is empty or not */
#define LIST_ISEMPTY(lh) ((lh)->n == (lh))
/* returns a pointer of type <pt> to a structure following the element
* which contains list head <lh>, which is known as element <el> 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 <pt> to a structure preceding the element
* which contains list head <lh>, which is known as element <el> 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 <item> through a list of items of type "typeof(*item)" which are
* linked via a "struct list" member named <member>. A pointer to the head of
* the list is passed in <list_head>. No temporary variable is needed. Note
* that <item> 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 <item> through the list starting from <item>
* 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 <item> through a list of items of type "typeof(*item)" which are
* linked via a "struct list" member named <member>. A pointer to the head of
* the list is passed in <list_head>. A temporary variable <back> of same type
* as <item> is needed so that <item> 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 <item> through the list starting from <item>
* 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 <common/hathreads.h>
#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; \
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; \
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) \
p->n = p2; \
(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 */
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