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Merge branch '1443-threadsanitizer-data-race-lib-dns-rbtdb-c-1960-in-decrement_reference-2' into 'master'

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Resolve "ThreadSanitizer: data race lib/dns/rbtdb.c:1960 in decrement_reference"

Closes #1443

See merge request isc-projects/bind9!2703
This commit is contained in:
Ondřej Surý 2019-12-09 18:48:35 +00:00
commit 09c2dbffb5
1 changed files with 51 additions and 36 deletions
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87
lib/dns/rbtdb.c
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@ -1824,6 +1824,31 @@ new_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
}
}
/*%
* The tree lock must be held for the result to be valid.
*/
static inline bool
is_leaf(dns_rbtnode_t *node) {
return (node->parent != NULL && node->parent->down == node &&
node->left == NULL && node->right == NULL);
}
static inline void
send_to_prune_tree(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
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));
new_reference(rbtdb, node);
db = NULL;
attach((dns_db_t *)rbtdb, &db);
ev->ev_sender = db;
isc_task_send(rbtdb->task, &ev);
}
/*%
* 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
@ -1844,28 +1869,29 @@ cleanup_dead_nodes(dns_rbtdb_t *rbtdb, int bucketnum) {
/*
* Since we're holding a tree write lock, it should be
* impossible for this node to be referenced by others.
*
* decrement_reference may not have tested node->down, as
* the tree_lock was not held, before adding the node to
* deadnodes so we test it here.
*/
INSIST(isc_refcount_current(&node->references) == 0 &&
node->data == NULL);
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));
new_reference(rbtdb, node);
db = NULL;
attach((dns_db_t *)rbtdb, &db);
ev->ev_sender = db;
isc_task_send(rbtdb->task, &ev);
} else {
if (is_leaf(node) && rbtdb->task != NULL) {
send_to_prune_tree(rbtdb, node);
} else if (node->down == NULL && node->data == NULL) {
/*
* Not a interior node and not needing to be
* reactivated.
*/
delete_node(rbtdb, node);
} else if (node->data == NULL) {
/*
* A interior node without data. Leave linked to
* to be cleaned up when node->down becomes NULL.
*/
ISC_LIST_APPEND(rbtdb->deadnodes[bucketnum],
node, deadlink);
}
node = ISC_LIST_HEAD(rbtdb->deadnodes[bucketnum]);
count--;
@ -1945,6 +1971,7 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
{
isc_result_t result;
bool write_locked;
bool locked = tlock != isc_rwlocktype_none;
rbtdb_nodelock_t *nodelock;
int bucket = node->locknum;
bool no_reference = true;
@ -1952,12 +1979,12 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
nodelock = &rbtdb->node_locks[bucket];
#define KEEP_NODE(n, r) \
((n)->data != NULL || (n)->down != NULL || \
#define KEEP_NODE(n, r, l) \
((n)->data != NULL || ((l) && (n)->down != NULL) || \
(n) == (r)->origin_node || (n) == (r)->nsec3_origin_node)
/* Handle easy and typical case first. */
if (!node->dirty && KEEP_NODE(node, rbtdb)) {
if (!node->dirty && KEEP_NODE(node, rbtdb, locked)) {
if (isc_refcount_decrement(&node->references) == 1) {
refs = isc_refcount_decrement(&nodelock->references);
INSIST(refs > 0);
@ -2024,8 +2051,9 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
refs = isc_refcount_decrement(&nodelock->references);
INSIST(refs > 0);
if (KEEP_NODE(node, rbtdb))
if (KEEP_NODE(node, rbtdb, locked || write_locked)) {
goto restore_locks;
}
#undef KEEP_NODE
@ -2050,21 +2078,8 @@ decrement_reference(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
* it's their responsibility to purge stale leaves (e.g. by
* periodic walk-through).
*/
if (!pruning && 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));
new_reference(rbtdb, node);
db = NULL;
attach((dns_db_t *)rbtdb, &db);
ev->ev_sender = db;
isc_task_send(rbtdb->task, &ev);
if (!pruning && is_leaf(node) && rbtdb->task != NULL) {
send_to_prune_tree(rbtdb, node);
no_reference = false;
} else {
delete_node(rbtdb, node);