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Merge branch 'ondrej/improve-newref-checks' into 'main'

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Improve the reference counting in newref()

See merge request isc-projects/bind9!8914
This commit is contained in:
Ondřej Surý
2024-04-30 18:43:39 +00:00
parent b1b9ac1cba c13a1d8b01
commit bc8095311a
1 changed files with 101 additions and 70 deletions
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171
lib/dns/qpcache.c
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@@ -709,11 +709,14 @@ delete_node(dns_qpdb_t *qpdb, dns_qpdata_t *node) {
}
/*
* Caller must be holding the node lock.
* The caller must specify its currect node and tree lock status.
* It's okay for neither lock to be held if there are existing external
* references to the node, but if this is the first external reference,
* then the caller must be holding at least one lock.
*/
static void
newref(dns_qpdb_t *qpdb, dns_qpdata_t *node,
isc_rwlocktype_t nlocktype DNS__DB_FLARG) {
newref(dns_qpdb_t *qpdb, dns_qpdata_t *node, isc_rwlocktype_t nlocktype,
isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
uint_fast32_t refs;
if (nlocktype == isc_rwlocktype_write &&
@@ -728,12 +731,20 @@ newref(dns_qpdb_t *qpdb, dns_qpdata_t *node,
#if DNS_DB_NODETRACE
fprintf(stderr, "incr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
func, file, line, node, refs + 1);
#else
UNUSED(refs);
#endif
if (refs == 0) {
/* this is the first external reference to the node */
/*
* this is the first external reference to the node.
*
* we need to hold the node or tree lock to avoid
* incrementing the reference count while also deleting
* the node. delete_node() is always protected by both
* tree and node locks being write-locked.
*/
INSIST(nlocktype != isc_rwlocktype_none ||
tlocktype != isc_rwlocktype_none);
refs = isc_refcount_increment0(
&qpdb->node_locks[node->locknum].references);
#if DNS_DB_NODETRACE
@@ -1014,14 +1025,13 @@ setttl(dns_slabheader_t *header, dns_ttl_t newttl) {
* Caller must hold the node (write) lock.
*/
static void
expireheader(dns_slabheader_t *header, isc_rwlocktype_t *tlocktypep,
dns_expire_t reason DNS__DB_FLARG) {
expireheader(dns_slabheader_t *header, isc_rwlocktype_t *nlocktypep,
isc_rwlocktype_t *tlocktypep, dns_expire_t reason DNS__DB_FLARG) {
setttl(header, 0);
mark(header, DNS_SLABHEADERATTR_ANCIENT);
QPDB_HEADERNODE(header)->dirty = 1;
if (isc_refcount_current(&QPDB_HEADERNODE(header)->erefs) == 0) {
isc_rwlocktype_t nlocktype = isc_rwlocktype_write;
dns_qpdb_t *qpdb = (dns_qpdb_t *)header->db;
/*
@@ -1029,9 +1039,9 @@ expireheader(dns_slabheader_t *header, isc_rwlocktype_t *tlocktypep,
* We first need to gain a new reference to the node to meet a
* requirement of decref().
*/
newref(qpdb, QPDB_HEADERNODE(header),
nlocktype DNS__DB_FLARG_PASS);
decref(qpdb, QPDB_HEADERNODE(header), 0, &nlocktype, tlocktypep,
newref(qpdb, QPDB_HEADERNODE(header), *nlocktypep,
*tlocktypep DNS__DB_FLARG_PASS);
decref(qpdb, QPDB_HEADERNODE(header), 0, nlocktypep, tlocktypep,
true, false DNS__DB_FLARG_PASS);
if (qpdb->cachestats == NULL) {
@@ -1083,7 +1093,8 @@ update_cachestats(dns_qpdb_t *qpdb, isc_result_t result) {
static void
bindrdataset(dns_qpdb_t *qpdb, dns_qpdata_t *node, dns_slabheader_t *header,
isc_stdtime_t now, isc_rwlocktype_t locktype,
isc_stdtime_t now, isc_rwlocktype_t nlocktype,
isc_rwlocktype_t tlocktype,
dns_rdataset_t *rdataset DNS__DB_FLARG) {
bool stale = STALE(header);
bool ancient = ANCIENT(header);
@@ -1100,7 +1111,7 @@ bindrdataset(dns_qpdb_t *qpdb, dns_qpdata_t *node, dns_slabheader_t *header,
return;
}
newref(qpdb, node, locktype DNS__DB_FLARG_PASS);
newref(qpdb, node, nlocktype, tlocktype DNS__DB_FLARG_PASS);
INSIST(rdataset->methods == NULL); /* We must be disassociated. */
@@ -1188,7 +1199,8 @@ bindrdataset(dns_qpdb_t *qpdb, dns_qpdata_t *node, dns_slabheader_t *header,
static isc_result_t
setup_delegation(qpdb_search_t *search, dns_dbnode_t **nodep,
dns_name_t *foundname, dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset DNS__DB_FLARG) {
dns_rdataset_t *sigrdataset,
isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
dns_name_t *zcname = NULL;
dns_typepair_t type;
dns_qpdata_t *node = NULL;
@@ -1229,12 +1241,12 @@ setup_delegation(qpdb_search_t *search, dns_dbnode_t **nodep,
NODE_RDLOCK(&(search->qpdb->node_locks[node->locknum].lock),
&nlocktype);
bindrdataset(search->qpdb, node, search->zonecut_header,
search->now, isc_rwlocktype_read,
search->now, nlocktype, tlocktype,
rdataset DNS__DB_FLARG_PASS);
if (sigrdataset != NULL && search->zonecut_sigheader != NULL) {
bindrdataset(search->qpdb, node,
search->zonecut_sigheader, search->now,
isc_rwlocktype_read,
nlocktype, tlocktype,
sigrdataset DNS__DB_FLARG_PASS);
}
NODE_UNLOCK(&(search->qpdb->node_locks[node->locknum].lock),
@@ -1400,7 +1412,8 @@ check_zonecut(dns_qpdata_t *node, void *arg DNS__DB_FLARG) {
* We increment the reference count on node to ensure that
* search->zonecut_header will still be valid later.
*/
newref(search->qpdb, node, nlocktype DNS__DB_FLARG_PASS);
newref(search->qpdb, node, nlocktype,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
search->zonecut = node;
search->zonecut_header = dname_header;
search->zonecut_sigheader = sigdname_header;
@@ -1485,15 +1498,17 @@ find_deepest_zonecut(qpdb_search_t *search, dns_qpdata_t *node,
}
result = DNS_R_DELEGATION;
if (nodep != NULL) {
newref(search->qpdb, node,
nlocktype DNS__DB_FLARG_PASS);
newref(search->qpdb, node, nlocktype,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
*nodep = node;
}
bindrdataset(search->qpdb, node, found, search->now,
nlocktype, rdataset DNS__DB_FLARG_PASS);
nlocktype, isc_rwlocktype_none,
rdataset DNS__DB_FLARG_PASS);
if (foundsig != NULL) {
bindrdataset(search->qpdb, node, foundsig,
search->now, nlocktype,
isc_rwlocktype_none,
sigrdataset DNS__DB_FLARG_PASS);
}
if (need_headerupdate(found, search->now) ||
@@ -1612,12 +1627,14 @@ find_coveringnsec(qpdb_search_t *search, const dns_name_t *name,
}
if (found != NULL) {
bindrdataset(search->qpdb, node, found, now, nlocktype,
rdataset DNS__DB_FLARG_PASS);
isc_rwlocktype_none, rdataset DNS__DB_FLARG_PASS);
if (foundsig != NULL) {
bindrdataset(search->qpdb, node, foundsig, now,
nlocktype, sigrdataset DNS__DB_FLARG_PASS);
nlocktype, isc_rwlocktype_none,
sigrdataset DNS__DB_FLARG_PASS);
}
newref(search->qpdb, node, nlocktype DNS__DB_FLARG_PASS);
newref(search->qpdb, node, nlocktype,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
dns_name_copy(fname, foundname);
@@ -1728,9 +1745,9 @@ find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
}
}
if (search.zonecut != NULL) {
result = setup_delegation(
&search, nodep, foundname, rdataset,
sigrdataset DNS__DB_FLARG_PASS);
result = setup_delegation(&search, nodep, foundname,
rdataset, sigrdataset,
tlocktype DNS__DB_FLARG_PASS);
goto tree_exit;
} else {
find_ns:
@@ -1910,18 +1927,19 @@ find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
nsecheader != NULL)
{
if (nodep != NULL) {
newref(search.qpdb, node,
nlocktype DNS__DB_FLARG_PASS);
newref(search.qpdb, node, nlocktype,
tlocktype DNS__DB_FLARG_PASS);
*nodep = node;
}
bindrdataset(search.qpdb, node, nsecheader, search.now,
nlocktype, rdataset DNS__DB_FLARG_PASS);
nlocktype, tlocktype,
rdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(nsecheader, search.now)) {
update = nsecheader;
}
if (nsecsig != NULL) {
bindrdataset(search.qpdb, node, nsecsig,
search.now, nlocktype,
search.now, nlocktype, tlocktype,
sigrdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(nsecsig, search.now)) {
updatesig = nsecsig;
@@ -1953,18 +1971,19 @@ find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
*/
if (nsheader != NULL) {
if (nodep != NULL) {
newref(search.qpdb, node,
nlocktype DNS__DB_FLARG_PASS);
newref(search.qpdb, node, nlocktype,
tlocktype DNS__DB_FLARG_PASS);
*nodep = node;
}
bindrdataset(search.qpdb, node, nsheader, search.now,
nlocktype, rdataset DNS__DB_FLARG_PASS);
nlocktype, tlocktype,
rdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(nsheader, search.now)) {
update = nsheader;
}
if (nssig != NULL) {
bindrdataset(search.qpdb, node, nssig,
search.now, nlocktype,
search.now, nlocktype, tlocktype,
sigrdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(nssig, search.now)) {
updatesig = nssig;
@@ -1986,7 +2005,8 @@ find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
*/
if (nodep != NULL) {
newref(search.qpdb, node, nlocktype DNS__DB_FLARG_PASS);
newref(search.qpdb, node, nlocktype,
tlocktype DNS__DB_FLARG_PASS);
*nodep = node;
}
@@ -2019,13 +2039,14 @@ find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
result == DNS_R_NCACHENXRRSET)
{
bindrdataset(search.qpdb, node, found, search.now, nlocktype,
rdataset DNS__DB_FLARG_PASS);
tlocktype, rdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(found, search.now)) {
update = found;
}
if (!NEGATIVE(found) && foundsig != NULL) {
bindrdataset(search.qpdb, node, foundsig, search.now,
nlocktype, sigrdataset DNS__DB_FLARG_PASS);
nlocktype, tlocktype,
sigrdataset DNS__DB_FLARG_PASS);
if (need_headerupdate(foundsig, search.now)) {
updatesig = foundsig;
}
@@ -2203,15 +2224,16 @@ findzonecut(dns_db_t *db, const dns_name_t *name, unsigned int options,
}
if (nodep != NULL) {
newref(search.qpdb, node, nlocktype DNS__DB_FLARG_PASS);
newref(search.qpdb, node, nlocktype,
tlocktype DNS__DB_FLARG_PASS);
*nodep = node;
}
bindrdataset(search.qpdb, node, found, search.now, nlocktype,
bindrdataset(search.qpdb, node, found, search.now, nlocktype, tlocktype,
rdataset DNS__DB_FLARG_PASS);
if (foundsig != NULL) {
bindrdataset(search.qpdb, node, foundsig, search.now, nlocktype,
sigrdataset DNS__DB_FLARG_PASS);
tlocktype, sigrdataset DNS__DB_FLARG_PASS);
}
if (need_headerupdate(found, search.now) ||
@@ -2316,9 +2338,10 @@ findrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
}
if (found != NULL) {
bindrdataset(qpdb, qpnode, found, now, nlocktype,
rdataset DNS__DB_FLARG_PASS);
isc_rwlocktype_none, rdataset DNS__DB_FLARG_PASS);
if (!NEGATIVE(found) && foundsig != NULL) {
bindrdataset(qpdb, qpnode, foundsig, now, nlocktype,
isc_rwlocktype_none,
sigrdataset DNS__DB_FLARG_PASS);
}
}
@@ -2422,7 +2445,8 @@ expiredata(dns_db_t *db, dns_dbnode_t *node, void *data) {
isc_rwlocktype_t tlocktype = isc_rwlocktype_none;
NODE_WRLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
expireheader(header, &tlocktype, dns_expire_flush DNS__DB_FILELINE);
expireheader(header, &nlocktype, &tlocktype,
dns_expire_flush DNS__DB_FILELINE);
NODE_UNLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
INSIST(tlocktype == isc_rwlocktype_none);
}
@@ -2439,7 +2463,7 @@ rdataset_size(dns_slabheader_t *header) {
static size_t
expire_lru_headers(dns_qpdb_t *qpdb, unsigned int locknum,
isc_rwlocktype_t *tlocktypep,
isc_rwlocktype_t *nlocktypep, isc_rwlocktype_t *tlocktypep,
size_t purgesize DNS__DB_FLARG) {
dns_slabheader_t *header = NULL;
size_t purged = 0;
@@ -2459,7 +2483,7 @@ expire_lru_headers(dns_qpdb_t *qpdb, unsigned int locknum,
* TTL will be reset to 0.
*/
ISC_LIST_UNLINK(qpdb->lru[locknum], header, link);
expireheader(header, tlocktypep,
expireheader(header, nlocktypep, tlocktypep,
dns_expire_lru DNS__DB_FLARG_PASS);
purged += header_size;
}
@@ -2493,9 +2517,9 @@ again:
isc_rwlocktype_t nlocktype = isc_rwlocktype_none;
NODE_WRLOCK(&qpdb->node_locks[locknum].lock, &nlocktype);
purged += expire_lru_headers(qpdb, locknum, tlocktypep,
purgesize -
purged DNS__DB_FLARG_PASS);
purged += expire_lru_headers(
qpdb, locknum, &nlocktype, tlocktypep,
purgesize - purged DNS__DB_FLARG_PASS);
/*
* Work out the oldest remaining last_used values of the list
@@ -2847,7 +2871,7 @@ reactivate_node(dns_qpdb_t *qpdb, dns_qpdata_t *node,
}
}
newref(qpdb, node, nlocktype DNS__DB_FLARG_PASS);
newref(qpdb, node, nlocktype, tlocktype DNS__DB_FLARG_PASS);
NODE_UNLOCK(nodelock, &nlocktype);
}
@@ -2923,7 +2947,8 @@ attachnode(dns_db_t *db, dns_dbnode_t *source,
dns_qpdb_t *qpdb = (dns_qpdb_t *)db;
dns_qpdata_t *node = (dns_qpdata_t *)source;
newref(qpdb, node, isc_rwlocktype_none DNS__DB_FLARG_PASS);
newref(qpdb, node, isc_rwlocktype_none,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
*targetp = source;
}
@@ -3056,7 +3081,8 @@ allrdatasets(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
iterator->common.now = now;
iterator->current = NULL;
newref(qpdb, qpnode, isc_rwlocktype_none DNS__DB_FLARG_PASS);
newref(qpdb, qpnode, isc_rwlocktype_none,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
*iteratorp = (dns_rdatasetiter_t *)iterator;
@@ -3067,7 +3093,8 @@ static isc_result_t
add(dns_qpdb_t *qpdb, dns_qpdata_t *qpnode,
const dns_name_t *nodename ISC_ATTR_UNUSED, dns_slabheader_t *newheader,
unsigned int options, bool loading, dns_rdataset_t *addedrdataset,
isc_stdtime_t now DNS__DB_FLARG) {
isc_stdtime_t now, isc_rwlocktype_t nlocktype,
isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
dns_slabheader_t *topheader = NULL, *topheader_prev = NULL;
dns_slabheader_t *header = NULL, *sigheader = NULL;
dns_slabheader_t *prioheader = NULL;
@@ -3158,8 +3185,8 @@ add(dns_qpdb_t *qpdb, dns_qpdata_t *qpnode,
if (addedrdataset != NULL) {
bindrdataset(
qpdb, qpnode, topheader,
now,
isc_rwlocktype_write,
now, nlocktype,
tlocktype,
addedrdataset
DNS__DB_FLARG_PASS);
}
@@ -3224,7 +3251,7 @@ find_header:
dns_slabheader_destroy(&newheader);
if (addedrdataset != NULL) {
bindrdataset(qpdb, qpnode, header, now,
isc_rwlocktype_write,
nlocktype, tlocktype,
addedrdataset DNS__DB_FLARG_PASS);
}
return (DNS_R_UNCHANGED);
@@ -3280,7 +3307,7 @@ find_header:
dns_slabheader_destroy(&newheader);
if (addedrdataset != NULL) {
bindrdataset(qpdb, qpnode, header, now,
isc_rwlocktype_write,
nlocktype, tlocktype,
addedrdataset DNS__DB_FLARG_PASS);
}
return (ISC_R_SUCCESS);
@@ -3344,7 +3371,7 @@ find_header:
dns_slabheader_destroy(&newheader);
if (addedrdataset != NULL) {
bindrdataset(qpdb, qpnode, header, now,
isc_rwlocktype_write,
nlocktype, tlocktype,
addedrdataset DNS__DB_FLARG_PASS);
}
return (ISC_R_SUCCESS);
@@ -3470,7 +3497,7 @@ find_header:
}
if (addedrdataset != NULL) {
bindrdataset(qpdb, qpnode, newheader, now, isc_rwlocktype_write,
bindrdataset(qpdb, qpnode, newheader, now, nlocktype, tlocktype,
addedrdataset DNS__DB_FLARG_PASS);
}
@@ -3556,8 +3583,8 @@ cleanup:
static void
expire_ttl_headers(dns_qpdb_t *qpdb, unsigned int locknum,
isc_rwlocktype_t *tlocktypep, isc_stdtime_t now,
bool cache_is_overmem DNS__DB_FLARG);
isc_rwlocktype_t *nlocktypep, isc_rwlocktype_t *tlocktypep,
isc_stdtime_t now, bool cache_is_overmem DNS__DB_FLARG);
static isc_result_t
addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
@@ -3689,7 +3716,7 @@ addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
cleanup_dead_nodes(qpdb, qpnode->locknum DNS__DB_FLARG_PASS);
}
expire_ttl_headers(qpdb, qpnode->locknum, &tlocktype, now,
expire_ttl_headers(qpdb, qpnode->locknum, &nlocktype, &tlocktype, now,
cache_is_overmem DNS__DB_FLARG_PASS);
/*
@@ -3722,7 +3749,8 @@ addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
if (result == ISC_R_SUCCESS) {
result = add(qpdb, qpnode, name, newheader, options, false,
addedrdataset, now DNS__DB_FLARG_PASS);
addedrdataset, now, nlocktype,
tlocktype DNS__DB_FLARG_PASS);
}
if (result == ISC_R_SUCCESS && delegating) {
qpnode->find_callback = 1;
@@ -3764,7 +3792,8 @@ deleterdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
NODE_WRLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
result = add(qpdb, qpnode, NULL, newheader, DNS_DBADD_FORCE, false,
NULL, 0 DNS__DB_FLARG_PASS);
NULL, 0, nlocktype,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
NODE_UNLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
return (result);
@@ -3825,7 +3854,8 @@ getoriginnode(dns_db_t *db, dns_dbnode_t **nodep DNS__DB_FLARG) {
/* Note that the access to origin_node doesn't require a DB lock */
onode = (dns_qpdata_t *)qpdb->origin_node;
if (onode != NULL) {
newref(qpdb, onode, isc_rwlocktype_none DNS__DB_FLARG_PASS);
newref(qpdb, onode, isc_rwlocktype_none,
isc_rwlocktype_none DNS__DB_FLARG_PASS);
*nodep = qpdb->origin_node;
} else {
result = ISC_R_NOTFOUND;
@@ -4161,8 +4191,8 @@ rdatasetiter_current(dns_rdatasetiter_t *iterator,
NODE_RDLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
bindrdataset(qpdb, qpnode, header, rbtiterator->common.now,
isc_rwlocktype_read, rdataset DNS__DB_FLARG_PASS);
bindrdataset(qpdb, qpnode, header, rbtiterator->common.now, nlocktype,
isc_rwlocktype_none, rdataset DNS__DB_FLARG_PASS);
NODE_UNLOCK(&qpdb->node_locks[qpnode->locknum].lock, &nlocktype);
}
@@ -4642,7 +4672,8 @@ dbiterator_current(dns_dbiterator_t *iterator, dns_dbnode_t **nodep,
result = ISC_R_SUCCESS;
}
newref(qpdb, node, isc_rwlocktype_none DNS__DB_FLARG_PASS);
newref(qpdb, node, isc_rwlocktype_none,
qpdbiter->tree_locked DNS__DB_FLARG_PASS);
*nodep = qpdbiter->node;
@@ -4720,8 +4751,8 @@ deletedata(dns_db_t *db ISC_ATTR_UNUSED, dns_dbnode_t *node ISC_ATTR_UNUSED,
*/
static void
expire_ttl_headers(dns_qpdb_t *qpdb, unsigned int locknum,
isc_rwlocktype_t *tlocktypep, isc_stdtime_t now,
bool cache_is_overmem DNS__DB_FLARG) {
isc_rwlocktype_t *nlocktypep, isc_rwlocktype_t *tlocktypep,
isc_stdtime_t now, bool cache_is_overmem DNS__DB_FLARG) {
isc_heap_t *heap = qpdb->heaps[locknum];
for (size_t i = 0; i < DNS_QPDB_EXPIRE_TTL_COUNT; i++) {
@@ -4749,7 +4780,7 @@ expire_ttl_headers(dns_qpdb_t *qpdb, unsigned int locknum,
return;
}
expireheader(header, tlocktypep,
expireheader(header, tlocktypep, nlocktypep,
dns_expire_ttl DNS__DB_FLARG_PASS);
}
}