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https://github.com/isc-projects/bind9.git
synced 2026-05-28 04:34:54 -04:00
fix: usr: Avoid unnecessary locking in the zone/cache database
Prevent lock contention among many worker threads referring to the same database node at the same time. This would improve zone and cache database performance for the heavily contended database nodes. Closes #5130 Merge branch '5130-reduce-lock-contention-in-decrement-reference' into 'main' See merge request isc-projects/bind9!9963
This commit is contained in:
Ondřej Surý
commit
48471fd50c
2 changed files with 102 additions and 90 deletions
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@ -616,12 +616,9 @@ delete_node(qpcache_t *qpdb, qpcnode_t *node) {
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* then the caller must be holding at least one lock.
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*/
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static void
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newref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t nlocktype,
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isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
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uint_fast32_t refs;
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qpcnode_ref(node);
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refs = isc_refcount_increment0(&node->erefs);
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qpcnode_newref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t nlocktype,
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isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
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uint_fast32_t refs = isc_refcount_increment0(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr, "incr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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@ -654,6 +651,13 @@ newref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t nlocktype,
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}
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}
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static void
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newref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t nlocktype,
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isc_rwlocktype_t tlocktype DNS__DB_FLARG) {
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qpcnode_ref(node);
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qpcnode_newref(qpdb, node, nlocktype, tlocktype DNS__DB_FLARG_PASS);
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}
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static void
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cleanup_deadnodes(void *arg);
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@ -679,45 +683,45 @@ decref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t *nlocktypep,
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isc_result_t result;
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bool locked = *tlocktypep != isc_rwlocktype_none;
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bool write_locked = false;
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db_nodelock_t *nodelock = NULL;
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int bucket = node->locknum;
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db_nodelock_t *nodelock = &qpdb->node_locks[bucket];
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uint_fast32_t refs;
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REQUIRE(*nlocktypep != isc_rwlocktype_none);
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nodelock = &qpdb->node_locks[bucket];
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refs = isc_refcount_decrement(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr, "decr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs - 1);
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#endif
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if (refs > 1) {
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qpcnode_unref(node);
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return false;
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}
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#define KEEP_NODE(n, r) ((n)->data != NULL || (n) == (r)->origin_node)
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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/* Handle easy and typical case first. */
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if (!node->dirty && KEEP_NODE(node, qpdb)) {
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bool no_reference = false;
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refs = isc_refcount_decrement(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs - 1);
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#else
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UNUSED(refs);
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#endif
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if (refs == 1) {
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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no_reference = true;
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}
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if (!node->dirty && (node->data != NULL || node == qpdb->origin_node)) {
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qpcnode_unref(node);
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return no_reference;
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return false;
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}
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/*
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* Node lock ref has decremented to 0 and we may need to clean up the
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* node. To clean it up, the node ref needs to decrement to 0 under the
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* node write lock, so we regain the ref and try again.
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*/
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qpcnode_newref(qpdb, node, *nlocktypep, *tlocktypep DNS__DB_FLARG_PASS);
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/* Upgrade the lock? */
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if (*nlocktypep == isc_rwlocktype_read) {
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NODE_FORCEUPGRADE(&nodelock->lock, nlocktypep);
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@ -734,8 +738,6 @@ decref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t *nlocktypep,
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return false;
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}
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INSIST(refs == 1);
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if (node->dirty) {
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clean_cache_node(qpdb, node);
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}
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@ -782,7 +784,7 @@ decref(qpcache_t *qpdb, qpcnode_t *node, isc_rwlocktype_t *nlocktypep,
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UNUSED(refs);
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#endif
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if (KEEP_NODE(node, qpdb)) {
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if (node->data != NULL || node == qpdb->origin_node) {
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goto restore_locks;
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}
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116
lib/dns/qpzone.c
116
lib/dns/qpzone.c
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@ -727,16 +727,11 @@ dns__qpzone_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type,
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}
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static void
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newref(qpzonedb_t *qpdb, qpznode_t *node DNS__DB_FLARG) {
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uint_fast32_t refs;
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qpznode_ref(node);
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refs = isc_refcount_increment0(&node->erefs);
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qpznode_newref(qpzonedb_t *qpdb, qpznode_t *node DNS__DB_FLARG) {
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uint_fast32_t refs = isc_refcount_increment0(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr, "incr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs + 1);
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#else
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UNUSED(refs);
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#endif
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if (refs == 0) {
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@ -755,6 +750,12 @@ newref(qpzonedb_t *qpdb, qpznode_t *node DNS__DB_FLARG) {
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}
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}
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static void
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newref(qpzonedb_t *qpdb, qpznode_t *node DNS__DB_FLARG) {
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qpznode_ref(node);
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qpznode_newref(qpdb, node DNS__DB_FLARG_PASS);
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}
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static void
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clean_zone_node(qpznode_t *node, uint32_t least_serial) {
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dns_slabheader_t *current = NULL, *dcurrent = NULL;
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@ -890,40 +891,47 @@ clean_zone_node(qpznode_t *node, uint32_t least_serial) {
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static void
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decref(qpzonedb_t *qpdb, qpznode_t *node, uint32_t least_serial,
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isc_rwlocktype_t *nlocktypep DNS__DB_FLARG) {
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db_nodelock_t *nodelock = NULL;
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int bucket = node->locknum;
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db_nodelock_t *nodelock = &qpdb->node_locks[bucket];
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uint_fast32_t refs;
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REQUIRE(*nlocktypep != isc_rwlocktype_none);
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nodelock = &qpdb->node_locks[bucket];
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refs = isc_refcount_decrement(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr, "decr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs - 1);
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#endif
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if (refs > 1) {
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qpznode_unref(node);
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return;
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}
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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/* Handle easy and typical case first. */
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if (!node->dirty && (node->data != NULL || node == qpdb->origin ||
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node == qpdb->nsec3_origin))
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{
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refs = isc_refcount_decrement(&node->erefs);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs - 1);
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#else
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UNUSED(refs);
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#endif
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if (refs == 1) {
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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}
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goto done;
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qpznode_unref(node);
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return;
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}
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/*
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* Node lock ref has decremented to 0 and we may need to clean up the
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* node. To clean it up, the node ref needs to decrement to 0 under the
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* node write lock, so we regain the ref and try again.
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*/
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qpznode_newref(qpdb, node DNS__DB_FLARG_PASS);
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/* Upgrade the lock? */
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if (*nlocktypep == isc_rwlocktype_read) {
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NODE_FORCEUPGRADE(&nodelock->lock, nlocktypep);
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@ -934,32 +942,34 @@ decref(qpzonedb_t *qpdb, qpznode_t *node, uint32_t least_serial,
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fprintf(stderr, "decr:node:%s:%s:%u:%p->erefs = %" PRIuFAST32 "\n",
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func, file, line, node, refs - 1);
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#endif
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if (refs == 1) {
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if (node->dirty) {
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if (least_serial == 0) {
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/*
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* Caller doesn't know the least serial.
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* Get it.
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*/
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RWLOCK(&qpdb->lock, isc_rwlocktype_read);
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least_serial = qpdb->least_serial;
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RWUNLOCK(&qpdb->lock, isc_rwlocktype_read);
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}
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clean_zone_node(node, least_serial);
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}
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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if (refs > 1) {
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qpznode_unref(node);
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return;
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}
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done:
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if (node->dirty) {
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if (least_serial == 0) {
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/*
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* Caller doesn't know the least serial.
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* Get it.
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*/
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RWLOCK(&qpdb->lock, isc_rwlocktype_read);
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least_serial = qpdb->least_serial;
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RWUNLOCK(&qpdb->lock, isc_rwlocktype_read);
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}
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clean_zone_node(node, least_serial);
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}
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refs = isc_refcount_decrement(&nodelock->references);
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#if DNS_DB_NODETRACE
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fprintf(stderr,
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"decr:nodelock:%s:%s:%u:%p:%p->references = "
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"%" PRIuFAST32 "\n",
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func, file, line, node, nodelock, refs - 1);
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#else
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UNUSED(refs);
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#endif
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qpznode_unref(node);
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}
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