mirrors/haproxy
1
0
Fork 0
mirror of https://git.haproxy.org/git/haproxy.git/ synced 2025-08-10 00:57:02 +02:00
Code Issues Projects Releases Wiki Activity

BUG/MEDIUM: lists: Lock the element while we check if it is in a list.

Browse Source 
In MT_LIST_TRY_ADDQ() and MT_LIST_TRY_ADD() we can't just check if the
element is already in a list, because there's a small race condition, it
could be added  between the time we checked, and the time we actually set
its next and prev, so we have to lock it first.

This is required to address issue #958.

This should be backported to 2.3, 2.2 and 2.1.
This commit is contained in:
Olivier Houchard 2020-11-25 20:38:00 +01:00 committed by Willy Tarreau
parent 8a069eb9a4
commit 1f05324cbe
1 changed files with 47 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
include/haproxy/list.h
View File

@ -230,8 +230,8 @@
int _ret = 0; \
struct mt_list *lh = (_lh), *el = (_el); \
while (1) { \
struct mt_list *n; \
struct mt_list *p; \
struct mt_list *n, *n2; \
struct mt_list *p, *p2; \
n = _HA_ATOMIC_XCHG(&(lh)->next, MT_LIST_BUSY); \
if (n == MT_LIST_BUSY) \
continue; \
@ -241,10 +241,29 @@
__ha_barrier_store(); \
continue; \
} \
if ((el)->next != (el) || (el)->prev != (el)) { \
(n)->prev = p; \
(lh)->next = n; \
n2 = _HA_ATOMIC_XCHG(&el->next, MT_LIST_BUSY); \
if (n2 != el) { /* element already linked */ \
if (n2 != MT_LIST_BUSY) \
el->next = n2; \
n->prev = p; \
__ha_barrier_store(); \
lh->next = n; \
__ha_barrier_store(); \
if (n2 == MT_LIST_BUSY) \
continue; \
break; \
} \
p2 = _HA_ATOMIC_XCHG(&el->prev, MT_LIST_BUSY); \
if (p2 != el) { \
if (p2 != MT_LIST_BUSY) \
el->prev = p2; \
n->prev = p; \
el->next = el; \
__ha_barrier_store(); \
lh->next = n; \
__ha_barrier_store(); \
if (p2 == MT_LIST_BUSY) \
continue; \
break; \
} \
(el)->next = n; \
@ -270,8 +289,8 @@
int _ret = 0; \
struct mt_list *lh = (_lh), *el = (_el); \
while (1) { \
struct mt_list *n; \
struct mt_list *p; \
struct mt_list *n, *n2; \
struct mt_list *p, *p2; \
p = _HA_ATOMIC_XCHG(&(lh)->prev, MT_LIST_BUSY); \
if (p == MT_LIST_BUSY) \
continue; \
@ -281,10 +300,29 @@
__ha_barrier_store(); \
continue; \
} \
if ((el)->next != (el) || (el)->prev != (el)) { \
n2 = _HA_ATOMIC_XCHG(&el->next, MT_LIST_BUSY); \
if (n2 != el) { /* element already linked */ \
if (n2 != MT_LIST_BUSY) \
el->next = n2; \
p->next = n; \
(lh)->prev = p; \
__ha_barrier_store(); \
lh->prev = p; \
__ha_barrier_store(); \
if (n2 == MT_LIST_BUSY) \
continue; \
break; \
} \
p2 = _HA_ATOMIC_XCHG(&el->prev, MT_LIST_BUSY); \
if (p2 != el) { \
if (p2 != MT_LIST_BUSY) \
el->prev = p2; \
p->next = n; \
el->next = el; \
__ha_barrier_store(); \
lh->prev = p; \
__ha_barrier_store(); \
if (p2 == MT_LIST_BUSY) \
continue; \
break; \
} \
(el)->next = n; \