From: Alessio Podda Date: Tue, 8 Jul 2025 13:52:35 +0000 (+0200) Subject: Abstract bucket lock selection logic X-Git-Tag: v9.21.11~60^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c2a84bb17a40147affa16d4c0ccfbc1e61a2ad0a;p=thirdparty%2Fbind9.git Abstract bucket lock selection logic Recovering the node lock from a pointer to the header and a pointer to the db is a common operation. This commit abstracts it away into a function, so that the node lock selection logic may be modified more easily. --- diff --git a/lib/dns/qpzone.c b/lib/dns/qpzone.c index 9aed3409831..c3adb7127a8 100644 --- a/lib/dns/qpzone.c +++ b/lib/dns/qpzone.c @@ -91,7 +91,9 @@ #define QPDB_ATTR_LOADED 0x01 #define QPDB_ATTR_LOADING 0x02 +#ifndef DEFAULT_BUCKETS_COUNT #define DEFAULT_BUCKETS_COUNT 17 /*%< Should be prime. */ +#endif #define QPDBITER_NSEC3_ORIGIN_NODE(qpdb, iterator) \ ((iterator)->current == &(iterator)->nsec3iter && \ @@ -108,6 +110,15 @@ typedef struct qpzonedb qpzonedb_t; typedef struct qpznode qpznode_t; +typedef struct qpzone_bucket { + /* Per-bucket lock. */ + isc_rwlock_t lock; + + /* Padding to prevent false sharing between locks. */ + uint8_t __padding[ISC_OS_CACHELINE_SIZE - + (sizeof(isc_rwlock_t)) % ISC_OS_CACHELINE_SIZE]; +} qpzone_bucket_t; + typedef struct qpz_changed { qpznode_t *node; bool dirty; @@ -185,15 +196,6 @@ struct qpznode { void *data; }; -typedef struct qpzone_bucket { - /* Per-bucket lock. */ - isc_rwlock_t lock; - - /* Padding to prevent false sharing between locks. */ - uint8_t __padding[ISC_OS_CACHELINE_SIZE - - (sizeof(isc_rwlock_t)) % ISC_OS_CACHELINE_SIZE]; -} qpzone_bucket_t; - struct qpzonedb { /* Unlocked. */ dns_db_t common; @@ -239,8 +241,7 @@ struct qpzonedb { dns_qpmulti_t *nsec; /* NSEC nodes only */ dns_qpmulti_t *nsec3; /* NSEC3 nodes only */ - size_t buckets_count; - qpzone_bucket_t buckets[]; /* attribute((counted_by(buckets_count))) */ + qpzone_bucket_t buckets[DEFAULT_BUCKETS_COUNT]; }; #ifdef DNS_DB_NODETRACE @@ -404,6 +405,16 @@ static atomic_uint_fast16_t init_count = 0; * Failure to follow this hierarchy can result in deadlock. */ +static isc_rwlock_t * +qpzone_get_lock(qpzonedb_t *qpdb, qpznode_t *node) { + return &qpdb->buckets[node->locknum].lock; +} + +static uint16_t +qpzone_get_locknum(void) { + return isc_random_uniform(DEFAULT_BUCKETS_COUNT); +} + /*% * Return which RRset should be resigned sooner. If the RRsets have the * same signing time, prefer the other RRset over the SOA RRset. @@ -507,7 +518,7 @@ free_db_rcu(struct rcu_head *rcu_head) { if (dns_name_dynamic(&qpdb->common.origin)) { dns_name_free(&qpdb->common.origin, qpdb->common.mctx); } - for (size_t i = 0; i < qpdb->buckets_count; i++) { + for (size_t i = 0; i < DEFAULT_BUCKETS_COUNT; i++) { NODE_DESTROYLOCK(&qpdb->buckets[i].lock); } @@ -532,9 +543,7 @@ free_db_rcu(struct rcu_head *rcu_head) { INSIST(!cds_lfht_destroy(qpdb->common.update_listeners, NULL)); } - isc_mem_putanddetach(&qpdb->common.mctx, qpdb, - sizeof(*qpdb) + qpdb->buckets_count * - sizeof(qpdb->buckets[0])); + isc_mem_putanddetach(&qpdb->common.mctx, qpdb, sizeof(*qpdb)); } static void @@ -595,7 +604,7 @@ new_qpznode(qpzonedb_t *qpdb, const dns_name_t *name) { *newdata = (qpznode_t){ .name = DNS_NAME_INITEMPTY, .references = ISC_REFCOUNT_INITIALIZER(1), - .locknum = isc_random_uniform(qpdb->buckets_count), + .locknum = qpzone_get_locknum(), }; isc_mem_attach(qpdb->common.mctx, &newdata->mctx); @@ -636,14 +645,11 @@ dns__qpzone_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type, isc_result_t result; dns_qp_t *qp = NULL; - qpdb = isc_mem_get(mctx, - sizeof(*qpdb) + DEFAULT_BUCKETS_COUNT * - sizeof(qpdb->buckets[0])); + qpdb = isc_mem_get(mctx, sizeof(*qpdb)); *qpdb = (qpzonedb_t){ .common.origin = DNS_NAME_INITEMPTY, .common.rdclass = rdclass, .common.references = ISC_REFCOUNT_INITIALIZER(1), - .buckets_count = DEFAULT_BUCKETS_COUNT, .current_serial = 1, .least_serial = 1, .next_serial = 2, @@ -662,7 +668,7 @@ dns__qpzone_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type, isc_heap_create(mctx, resign_sooner, set_index, 0, &qpdb->heap); - for (size_t i = 0; i < qpdb->buckets_count; i++) { + for (size_t i = 0; i < DEFAULT_BUCKETS_COUNT; i++) { NODE_INITLOCK(&qpdb->buckets[i].lock); } @@ -944,7 +950,7 @@ qpznode_release(qpzonedb_t *qpdb, qpznode_t *node, uint32_t least_serial, * erefs_increment. If another thread acquires reference it * will be larger than 0, if it doesn't it is going to be 0. */ - isc_rwlock_t *nlock = &qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(qpdb, node); qpznode_erefs_increment(qpdb, node DNS__DB_FLARG_PASS); NODE_FORCEUPGRADE(nlock, nlocktypep); if (!qpznode_erefs_decrement(qpdb, node DNS__DB_FLARG_PASS)) { @@ -1038,7 +1044,7 @@ setnsec3parameters(dns_db_t *db, qpz_version_t *version) { version->havensec3 = false; node = qpdb->origin; - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_RDLOCK(nlock, &nlocktype); for (header = node->data; header != NULL; header = header_next) { header_next = header->next; @@ -1498,7 +1504,7 @@ closeversion(dns_db_t *db, dns_dbversion_t **versionp, ISC_LIST_UNLINK(resigned_list, header, link); - nlock = &qpdb->buckets[HEADERNODE(header)->locknum].lock; + nlock = qpzone_get_lock(qpdb, HEADERNODE(header)); NODE_WRLOCK(nlock, &nlocktype); if (rollback && !IGNORE(header)) { resigninsert(qpdb, header); @@ -1518,7 +1524,7 @@ closeversion(dns_db_t *db, dns_dbversion_t **versionp, isc_rwlocktype_t nlocktype = isc_rwlocktype_none; node = changed->node; - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_WRLOCK(nlock, &nlocktype); if (rollback) { @@ -1562,7 +1568,7 @@ qpzone_findrdataset(dns_db_t *db, dns_dbnode_t *dbnode, } serial = version->serial; - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_RDLOCK(nlock, &nlocktype); matchtype = DNS_TYPEPAIR_VALUE(type, covers); @@ -2168,7 +2174,7 @@ loading_addrdataset(void *arg, const dns_name_t *name, newheader->resign_lsb = rdataset->resign & 0x1; } - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_WRLOCK(nlock, &nlocktype); result = add(qpdb, node, name, qpdb->current_version, newheader, DNS_DBADD_MERGE, true, NULL, 0 DNS__DB_FLARG_PASS); @@ -2377,7 +2383,7 @@ setsigningtime(dns_db_t *db, dns_rdataset_t *rdataset, isc_stdtime_t resign) { header = dns_rdataset_getheader(rdataset); - nlock = &qpdb->buckets[HEADERNODE(header)->locknum].lock; + nlock = qpzone_get_lock(qpdb, HEADERNODE(header)); NODE_WRLOCK(nlock, &nlocktype); oldheader = *header; @@ -2420,7 +2426,6 @@ getsigningtime(dns_db_t *db, isc_stdtime_t *resign, dns_name_t *foundname, dns_slabheader_t *header = NULL; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; isc_rwlock_t *nlock = NULL; - uint16_t locknum; isc_result_t result = ISC_R_NOTFOUND; REQUIRE(VALID_QPZONE(qpdb)); @@ -2434,20 +2439,21 @@ getsigningtime(dns_db_t *db, isc_stdtime_t *resign, dns_name_t *foundname, RWUNLOCK(&qpdb->lock, isc_rwlocktype_read); return ISC_R_NOTFOUND; } - locknum = HEADERNODE(header)->locknum; + nlock = qpzone_get_lock(qpdb, HEADERNODE(header)); RWUNLOCK(&qpdb->lock, isc_rwlocktype_read); again: - nlock = &qpdb->buckets[locknum].lock; - NODE_RDLOCK(nlock, &nlocktype); RWLOCK(&qpdb->lock, isc_rwlocktype_read); header = isc_heap_element(qpdb->heap, 1); - if (header != NULL && HEADERNODE(header)->locknum != locknum) { + if (header != NULL && + qpzone_get_lock(qpdb, HEADERNODE(header)) != nlock) + { RWUNLOCK(&qpdb->lock, isc_rwlocktype_read); NODE_UNLOCK(nlock, &nlocktype); - locknum = HEADERNODE(header)->locknum; + + nlock = qpzone_get_lock(qpdb, HEADERNODE(header)); goto again; } @@ -2632,8 +2638,7 @@ qpzone_setup_delegation(qpz_search_t *search, dns_dbnode_t **nodep, } if (rdataset != NULL) { isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = - &search->qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(search->qpdb, node); NODE_RDLOCK(nlock, &nlocktype); bindrdataset(search->qpdb, node, search->zonecut_header, rdataset DNS__DB_FLARG_PASS); @@ -2673,7 +2678,7 @@ step(qpz_search_t *search, dns_qpiter_t *it, direction_t direction, result = dns_qpiter_current(it, nodename, (void **)&node, NULL); while (result == ISC_R_SUCCESS) { - isc_rwlock_t *nlock = &qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(qpdb, node); isc_rwlocktype_t nlocktype = isc_rwlocktype_none; dns_slabheader_t *header_next = NULL; @@ -2838,7 +2843,7 @@ find_wildcard(qpz_search_t *search, qpznode_t **nodep, dns_qpchain_node(&search->chain, i, NULL, (void **)&node, NULL); - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_RDLOCK(nlock, &nlocktype); /* * First we try to figure out if this node is active in @@ -2882,7 +2887,7 @@ find_wildcard(qpz_search_t *search, qpznode_t **nodep, * is active in the search's version, we're * done. */ - nlock = &qpdb->buckets[wnode->locknum].lock; + nlock = qpzone_get_lock(qpdb, wnode); NODE_RDLOCK(nlock, &nlocktype); for (header = wnode->data; header != NULL; header = header->next) @@ -3065,8 +3070,7 @@ again: do { dns_slabheader_t *found = NULL, *foundsig = NULL; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = - &search->qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(search->qpdb, node); NODE_RDLOCK(nlock, &nlocktype); empty_node = true; for (header = node->data; header != NULL; header = header_next) @@ -3209,7 +3213,7 @@ qpzone_check_zonecut(qpznode_t *node, void *arg DNS__DB_FLARG) { dns_slabheader_t *found = NULL; isc_result_t result = DNS_R_CONTINUE; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = &search->qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(search->qpdb, node); NODE_RDLOCK(nlock, &nlocktype); @@ -3498,7 +3502,7 @@ found: * have matched a wildcard. */ - nlock = &search.qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(search.qpdb, node); NODE_RDLOCK(nlock, &nlocktype); if (search.zonecut != NULL) { @@ -3860,7 +3864,7 @@ tree_exit: if (search.need_cleanup) { node = search.zonecut; INSIST(node != NULL); - nlock = &search.qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(search.qpdb, node); NODE_RDLOCK(nlock, &nlocktype); qpznode_release(search.qpdb, node, 0, @@ -3936,7 +3940,7 @@ qpzone_detachnode(dns_db_t *db, dns_dbnode_t **nodep DNS__DB_FLARG) { node = (qpznode_t *)(*nodep); *nodep = NULL; - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); /* * qpzone_destroy() uses call_rcu() API to destroy the node locks, so it @@ -4020,7 +4024,7 @@ locknode(dns_db_t *db, dns_dbnode_t *dbnode, isc_rwlocktype_t type) { qpzonedb_t *qpdb = (qpzonedb_t *)db; qpznode_t *node = (qpznode_t *)dbnode; - RWLOCK(&qpdb->buckets[node->locknum].lock, type); + RWLOCK(qpzone_get_lock(qpdb, node), type); } static void @@ -4028,7 +4032,7 @@ unlocknode(dns_db_t *db, dns_dbnode_t *dbnode, isc_rwlocktype_t type) { qpzonedb_t *qpdb = (qpzonedb_t *)db; qpznode_t *node = (qpznode_t *)dbnode; - RWUNLOCK(&qpdb->buckets[node->locknum].lock, type); + RWUNLOCK(qpzone_get_lock(qpdb, node), type); } static void @@ -4074,7 +4078,7 @@ rdatasetiter_first(dns_rdatasetiter_t *iterator DNS__DB_FLARG) { qpz_version_t *version = (qpz_version_t *)qrditer->common.version; dns_slabheader_t *header = NULL, *top_next = NULL; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = &qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(qpdb, node); NODE_RDLOCK(nlock, &nlocktype); @@ -4117,7 +4121,7 @@ rdatasetiter_next(dns_rdatasetiter_t *iterator DNS__DB_FLARG) { dns_slabheader_t *header = NULL; dns_slabheader_t *topheader, *topheader_next = NULL; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = &qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(qpdb, node); header = qrditer->current; if (header == NULL) { @@ -4175,7 +4179,7 @@ rdatasetiter_current(dns_rdatasetiter_t *iterator, qpznode_t *node = (qpznode_t *)qrditer->common.node; dns_slabheader_t *header = NULL; isc_rwlocktype_t nlocktype = isc_rwlocktype_none; - isc_rwlock_t *nlock = &qpdb->buckets[node->locknum].lock; + isc_rwlock_t *nlock = qpzone_get_lock(qpdb, node); header = qrditer->current; REQUIRE(header != NULL); @@ -4214,7 +4218,7 @@ dereference_iter_node(qpdb_dbiterator_t *iter DNS__DB_FLARG) { } iter->node = NULL; - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_RDLOCK(nlock, &nlocktype); qpznode_release(qpdb, node, 0, &nlocktype DNS__DB_FLARG_PASS); @@ -4710,7 +4714,7 @@ qpzone_addrdataset(dns_db_t *db, dns_dbnode_t *dbnode, * (Note: node lock must be acquired after starting * the QPDB transaction and released before committing.) */ - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_WRLOCK(nlock, &nlocktype); @@ -4804,7 +4808,7 @@ qpzone_subtractrdataset(dns_db_t *db, dns_dbnode_t *dbnode, newheader->resign_lsb = rdataset->resign & 0x1; } - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_WRLOCK(nlock, &nlocktype); changed = add_changed(newheader, version DNS__DB_FLARG_PASS); @@ -4966,7 +4970,7 @@ qpzone_deleterdataset(dns_db_t *db, dns_dbnode_t *dbnode, dns_name_copy(&node->name, nodename); - nlock = &qpdb->buckets[node->locknum].lock; + nlock = qpzone_get_lock(qpdb, node); NODE_WRLOCK(nlock, &nlocktype); result = add(qpdb, node, nodename, version, newheader, DNS_DBADD_FORCE, false, NULL, 0 DNS__DB_FLARG_PASS); @@ -4985,7 +4989,7 @@ nodefullname(dns_db_t *db, dns_dbnode_t *node, dns_name_t *name) { REQUIRE(node != NULL); REQUIRE(name != NULL); - nlock = &qpdb->buckets[qpnode->locknum].lock; + nlock = qpzone_get_lock(qpdb, qpnode); NODE_RDLOCK(nlock, &nlocktype); dns_name_copy(&qpnode->name, name); diff --git a/tests/dns/qpzone_test.c b/tests/dns/qpzone_test.c index 7e716bf024d..95c214d53ee 100644 --- a/tests/dns/qpzone_test.c +++ b/tests/dns/qpzone_test.c @@ -39,6 +39,7 @@ #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wshadow" #undef CHECK +#define DEFAULT_BUCKETS_COUNT 1 /*%< Should be prime. */ #include "qpzone.c" #pragma GCC diagnostic pop @@ -108,7 +109,6 @@ ownercase_test_one(const char *str1, const char *str2) { *qpdb = (qpzonedb_t){ .common.methods = &qpdb_zonemethods, .common.mctx = mctx, - .buckets_count = 1, }; qpznode_t node = { .locknum = 0 }; dns_slabheader_t header = { @@ -176,7 +176,6 @@ ISC_RUN_TEST_IMPL(setownercase) { *qpdb = (qpzonedb_t){ .common.methods = &qpdb_zonemethods, .common.mctx = mctx, - .buckets_count = 1, }; qpznode_t node = { .locknum = 0 }; dns_slabheader_t header = {