upstream/bind9
1
0
Fork 0
mirror of https://github.com/isc-projects/bind9.git synced 2026-06-12 19:29:59 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

3284. [bug] Address race conditions with the handling of

Browse source 
rbtnode.deadlink. [RT #27738]
This commit is contained in:
Mark Andrews 2012-02-15 02:02:10 +00:00
parent f5db1e08e7
commit 549f13385a
2 changed files with 49 additions and 45 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
CHANGES
View file

@ -1,3 +1,6 @@
3284. [bug] Address race conditions with the handling of
rbtnode.deadlink. [RT #27738]
3283. [bug] Raw zones with with more than 512 records in a RRset
failed to load. [RT #27863]

91
lib/dns/rbtdb.c
View file

@ -15,7 +15,7 @@
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: rbtdb.c,v 1.326.16.2 2012/02/09 23:46:51 tbox Exp $ */
/* $Id: rbtdb.c,v 1.326.16.3 2012/02/15 02:02:10 marka Exp $ */
/*! \file */
@ -1608,8 +1608,7 @@ cleanup_dead_nodes(dns_rbtdb_t *rbtdb, int bucketnum) {
}
/*
* Caller must be holding the node lock if its reference must be protected
* by the lock.
* Caller must be holding the node lock.
*/
static inline void
new_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
@ -1640,31 +1639,40 @@ static inline void
reactivate_node(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
isc_rwlocktype_t treelocktype)
{
isc_boolean_t need_relock = ISC_FALSE;
isc_rwlocktype_t locktype = isc_rwlocktype_read;
nodelock_t *nodelock = &rbtdb->node_locks[node->locknum].lock;
isc_boolean_t maybe_cleanup = ISC_FALSE;
NODE_STRONGLOCK(&rbtdb->node_locks[node->locknum].lock);
NODE_WEAKLOCK(&rbtdb->node_locks[node->locknum].lock,
isc_rwlocktype_read);
if (ISC_LINK_LINKED(node, deadlink))
need_relock = ISC_TRUE;
else if (!ISC_LIST_EMPTY(rbtdb->deadnodes[node->locknum]) &&
treelocktype == isc_rwlocktype_write)
need_relock = ISC_TRUE;
NODE_WEAKUNLOCK(&rbtdb->node_locks[node->locknum].lock,
isc_rwlocktype_read);
if (need_relock) {
NODE_WEAKLOCK(&rbtdb->node_locks[node->locknum].lock,
isc_rwlocktype_write);
NODE_STRONGLOCK(nodelock);
NODE_WEAKLOCK(nodelock, locktype);
/*
* Check if we can possibly cleanup the dead node. If so, upgrade
* the node lock below to perform the cleanup.
*/
if (!ISC_LIST_EMPTY(rbtdb->deadnodes[node->locknum]) &&
treelocktype == isc_rwlocktype_write) {
maybe_cleanup = ISC_TRUE;
}
if (ISC_LINK_LINKED(node, deadlink) || maybe_cleanup) {
/*
* Upgrade the lock and test if we still need to unlink.
*/
NODE_WEAKUNLOCK(nodelock, locktype);
locktype = isc_rwlocktype_write;
NODE_WEAKLOCK(nodelock, locktype);
if (ISC_LINK_LINKED(node, deadlink))
ISC_LIST_UNLINK(rbtdb->deadnodes[node->locknum],
node, deadlink);
if (treelocktype == isc_rwlocktype_write)
if (maybe_cleanup)
cleanup_dead_nodes(rbtdb, node->locknum);
NODE_WEAKUNLOCK(&rbtdb->node_locks[node->locknum].lock,
isc_rwlocktype_write);
}
new_reference(rbtdb, node);
NODE_STRONGUNLOCK(&rbtdb->node_locks[node->locknum].lock);
NODE_WEAKUNLOCK(nodelock, locktype);
NODE_STRONGUNLOCK(nodelock);
}
/*
@ -1688,7 +1696,7 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
rbtdb_nodelock_t *nodelock;
unsigned int refs, nrefs;
int bucket = node->locknum;
isc_boolean_t no_reference;
isc_boolean_t no_reference = ISC_TRUE;
nodelock = &rbtdb->node_locks[bucket];
@ -1708,6 +1716,7 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
NODE_WEAKUNLOCK(&nodelock->lock, isc_rwlocktype_read);
NODE_WEAKLOCK(&nodelock->lock, isc_rwlocktype_write);
}
dns_rbtnode_refdecrement(node, &nrefs);
INSIST((int)nrefs >= 0);
if (nrefs > 0) {
@ -1717,7 +1726,7 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
return (ISC_FALSE);
}
if (node->dirty && dns_rbtnode_refcurrent(node) == 0) {
if (node->dirty) {
if (IS_CACHE(rbtdb))
clean_cache_node(rbtdb, node);
else {
@ -1735,19 +1744,6 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
}
}
isc_refcount_decrement(&nodelock->references, &refs);
INSIST((int)refs >= 0);
/*
* XXXDCL should this only be done for cache zones?
*/
if (node->data != NULL || node->down != NULL) {
/* Restore the lock? */
if (nlock == isc_rwlocktype_read)
NODE_WEAKDOWNGRADE(&nodelock->lock);
return (ISC_TRUE);
}
/*
* Attempt to switch to a write lock on the tree. If this fails,
* we will add this node to a linked list of nodes in this locking
@ -1771,13 +1767,18 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
} else
write_locked = ISC_TRUE;
no_reference = ISC_TRUE;
if (write_locked && dns_rbtnode_refcurrent(node) == 0) {
isc_refcount_decrement(&nodelock->references, &refs);
INSIST((int)refs >= 0);
/*
* XXXDCL should this only be done for cache zones?
*/
if (node->data != NULL || node->down != NULL)
goto restore_locks;
if (write_locked) {
/*
* We can now delete the node if the reference counter is
* zero. This should be typically the case, but a different
* thread may still gain a (new) reference just before the
* current thread locks the tree (e.g., in findnode()).
* We can now delete the node.
*/
/*
@ -1852,13 +1853,13 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
delete_node(rbtdb, node);
}
} else if (dns_rbtnode_refcurrent(node) == 0) {
} else {
INSIST(node->data == NULL);
INSIST(!ISC_LINK_LINKED(node, deadlink));
ISC_LIST_APPEND(rbtdb->deadnodes[bucket], node, deadlink);
} else
no_reference = ISC_FALSE;
}
restore_locks:
/* Restore the lock? */
if (nlock == isc_rwlocktype_read)
NODE_WEAKDOWNGRADE(&nodelock->lock);