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4338. [bug] Reimplement change 4324 as it wasn't properly doing

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all the required book keeping. [RT #41941]
This commit is contained in:
Mark Andrews 2016-03-23 10:38:05 +11:00
parent 1cbfdb3c23
commit 558278974e
3 changed files with 61 additions and 98 deletions
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3
CHANGES
View file

@ -1,3 +1,6 @@
4338. [bug] Reimplement change 4324 as it wasn't properly doing
all the required book keeping. [RT #41941]
4337. [bug] The previous change exposed a latent flaw in
key refresh queries for managed-keys when
a cached DNSKEY had TTL 0. [RT #41986]

96
lib/dns/rbt.c
View file

@ -2114,91 +2114,29 @@ dns_rbt_deletenode(dns_rbt_t *rbt, dns_rbtnode_t *node, isc_boolean_t recurse)
}
}
for (;;) {
/*
* Note the node that points to the level of the node
* that is being deleted. If the deleted node is the
* top level, parent will be set to NULL.
*/
parent = get_upper_node(node);
/*
* Note the node that points to the level of the node
* that is being deleted. If the deleted node is the
* top level, parent will be set to NULL.
*/
parent = get_upper_node(node);
/*
* This node now has no down pointer (either because it didn't
* have one to start, or because it was recursively removed).
* So now the node needs to be removed from this level.
*/
deletefromlevel(node,
parent == NULL ? &rbt->root : &DOWN(parent));
/*
* This node now has no down pointer, so now it needs
* to be removed from this level.
*/
deletefromlevel(node, parent == NULL ? &rbt->root : &DOWN(parent));
if (DATA(node) != NULL && rbt->data_deleter != NULL)
rbt->data_deleter(DATA(node), rbt->deleter_arg);
if (DATA(node) != NULL && rbt->data_deleter != NULL)
rbt->data_deleter(DATA(node), rbt->deleter_arg);
unhash_node(rbt, node);
unhash_node(rbt, node);
#if DNS_RBT_USEMAGIC
node->magic = 0;
node->magic = 0;
#endif
dns_rbtnode_refdestroy(node);
dns_rbtnode_refdestroy(node);
freenode(rbt, &node);
/*
* There are now two special cases that can exist that
* would not have existed if the tree had been created
* using only the names that now exist in it. (This is
* all related to join_nodes() as described in this
* function's introductory comment.) Both cases exist
* when the deleted node's parent (the node that pointed
* to the deleted node's level) is not null but it has
* no data: parent != NULL && DATA(parent) == NULL.
*
* The first case is that the deleted node was the last
* on its level: DOWN(parent) == NULL. This case can
* only exist if the parent was previously deleted --
* and so now, apparently, the parent should go away.
* That can't be done though because there might be
* external references to it, such as through a
* nodechain. XXXMUKS: We don't care about this.
*
* The other case also involves a parent with no data,
* but with the deleted node being the next-to-last node
* instead of the last: LEFT(DOWN(parent)) == NULL &&
* RIGHT(DOWN(parent)) == NULL. Presumably now the
* remaining node on the level should be joined with the
* parent, but it's already been described why that
* can't be done.
*/
/*
* Is this the root?.
*/
if (parent == NULL)
break;
/*
* If the node deletion did not cause the subtree to disappear
* completely, return early.
*/
if (DOWN(parent) != NULL)
break;
/*
* If the upper node is not empty, it cannot be deleted.
*/
if (DATA(parent) != NULL)
break;
/*
* If upper node is the root node (.), don't attempt to
* delete it. The root node must always exist.
*/
if (parent == rbt->root)
break;
/*
* Ascend up the tree and delete the upper node.
*/
node = parent;
}
freenode(rbt, &node);
/*
* This function never fails.

60
lib/dns/rbtdb.c
View file

@ -1977,6 +1977,24 @@ delete_node(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
}
}
/*
* Caller must be holding the node lock.
*/
static inline void
new_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
unsigned int lockrefs, noderefs;
isc_refcount_t *lockref;
INSIST(!ISC_LINK_LINKED(node, deadlink));
dns_rbtnode_refincrement0(node, &noderefs);
if (noderefs == 1) { /* this is the first reference to the node */
lockref = &rbtdb->node_locks[node->locknum].references;
isc_refcount_increment0(lockref, &lockrefs);
INSIST(lockrefs != 0);
}
INSIST(noderefs != 0);
}
/*%
* Clean up dead nodes. These are nodes which have no references, and
* have no data. They are dead but we could not or chose not to delete
@ -2001,31 +2019,35 @@ cleanup_dead_nodes(dns_rbtdb_t *rbtdb, int bucketnum) {
INSIST(dns_rbtnode_refcurrent(node) == 0 &&
node->data == NULL);
delete_node(rbtdb, node);
if (node->parent != NULL &&
node->parent->down == node && node->left == NULL &&
node->right == NULL && rbtdb->task != NULL)
{
isc_event_t *ev;
dns_db_t *db;
ev = isc_event_allocate(rbtdb->common.mctx, NULL,
DNS_EVENT_RBTPRUNE,
prune_tree, node,
sizeof(isc_event_t));
if (ev != NULL) {
new_reference(rbtdb, node);
db = NULL;
attach((dns_db_t *)rbtdb, &db);
ev->ev_sender = db;
isc_task_send(rbtdb->task, &ev);
} else {
ISC_LIST_APPEND(rbtdb->deadnodes[bucketnum],
node, deadlink);
}
} else {
delete_node(rbtdb, node);
}
node = ISC_LIST_HEAD(rbtdb->deadnodes[bucketnum]);
count--;
}
}
/*
* Caller must be holding the node lock.
*/
static inline void
new_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
unsigned int lockrefs, noderefs;
isc_refcount_t *lockref;
INSIST(!ISC_LINK_LINKED(node, deadlink));
dns_rbtnode_refincrement0(node, &noderefs);
if (noderefs == 1) { /* this is the first reference to the node */
lockref = &rbtdb->node_locks[node->locknum].references;
isc_refcount_increment0(lockref, &lockrefs);
INSIST(lockrefs != 0);
}
INSIST(noderefs != 0);
}
/*
* This function is assumed to be called when a node is newly referenced
* and can be in the deadnode list. In that case the node must be retrieved