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remove node lock for settrust and clearprefetch

Browse source 
dns_rdataset_clearprefetch() performs an atomic operation,
so it didn't actually need to lock the database node.

dns_rdataset_settrust() updates header->trust; this is also
now atomic, so it doesn't need to lock the node now either.
This commit is contained in:
Evan Hunt 2025-08-04 21:26:01 -07:00
parent 4de396f955
commit 18db48eb2c
4 changed files with 33 additions and 31 deletions
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6
lib/dns/include/dns/rdataslab.h
View file

@ -83,13 +83,13 @@ struct dns_slabtop {
};
struct dns_slabheader {
_Atomic(uint16_t) attributes;
_Atomic(uint16_t) attributes;
_Atomic(dns_trust_t) trust;
/*%
* Locked by the owning node's lock.
*/
dns_trust_t trust;
uint32_t serial;
uint32_t serial;
union {
isc_stdtime_t expire;
dns_ttl_t ttl;

47
lib/dns/qpcache.c
View file

@ -1045,7 +1045,7 @@ bindrdataset(qpcache_t *qpdb, qpcnode_t *node, dns_slabheader_t *header,
rdataset->covers = DNS_TYPEPAIR_COVERS(header->typepair);
}
rdataset->ttl = !ZEROTTL(header) ? header->expire - now : 0;
rdataset->trust = header->trust;
rdataset->trust = atomic_load(&header->trust);
rdataset->resign = 0;
if (NEGATIVE(header)) {
@ -1313,7 +1313,7 @@ check_zonecut(qpcnode_t *node, void *arg DNS__DB_FLARG) {
}
}
if (found != NULL && (!DNS_TRUST_PENDING(found->trust) ||
if (found != NULL && (!DNS_TRUST_PENDING(atomic_load(&found->trust)) ||
(search->options & DNS_DBFIND_PENDINGOK) != 0))
{
/*
@ -1506,14 +1506,19 @@ find_coveringnsec(qpc_search_t *search, const dns_name_t *name,
return result;
}
#define MISSING_ANSWER(found, options) \
((found) == NULL || \
(DNS_TRUST_ADDITIONAL((found)->trust) && \
(((options) & DNS_DBFIND_ADDITIONALOK) == 0)) || \
((found)->trust == dns_trust_glue && \
(((options) & DNS_DBFIND_GLUEOK) == 0)) || \
(DNS_TRUST_PENDING((found)->trust) && \
(((options) & DNS_DBFIND_PENDINGOK) == 0)))
static inline bool
missing_answer(dns_slabheader_t *found, unsigned int options) {
if (found == NULL) {
return true;
}
dns_trust_t trust = atomic_load(&found->trust);
return (DNS_TRUST_ADDITIONAL(trust) &&
(options & DNS_DBFIND_ADDITIONALOK) == 0) ||
(DNS_TRUST_GLUE(trust) && (options & DNS_DBFIND_GLUEOK) == 0) ||
(DNS_TRUST_PENDING(trust) &&
(options & DNS_DBFIND_PENDINGOK) == 0);
}
static void
qpc_search_init(qpc_search_t *search, qpcache_t *db, unsigned int options,
@ -1698,7 +1703,7 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
empty_node = false;
if (header->noqname != NULL &&
header->trust == dns_trust_secure)
atomic_load(&header->trust) == dns_trust_secure)
{
found_noqname = true;
}
@ -1710,15 +1715,14 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
bool match = false;
if (related_headers(header, typepair, sigpair, &found,
&foundsig, &match) &&
!MISSING_ANSWER(found, options))
!missing_answer(found, options))
{
/*
* We can't exit early until we have an answer with
* sufficient trust level, see MISSING_ANSWER() macro
* for details, because we might need NS or NSEC
* sufficient trust level - see missing_answer()
* for details - because we might need NS or NSEC
* records.
*/
break;
}
@ -1808,7 +1812,7 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
/*
* If we didn't find what we were looking for...
*/
if (MISSING_ANSWER(found, options)) {
if (missing_answer(found, options)) {
/*
* Return covering NODATA NSEC record.
*/
@ -2748,7 +2752,8 @@ add(qpcache_t *qpdb, qpcnode_t *qpnode, dns_slabheader_t *newheader,
* data will supersede it below. Unclear what the best
* policy is here.
*/
if (trust < oldheader->trust &&
dns_trust_t oldtrust = atomic_load(&oldheader->trust);
if (trust < oldtrust &&
(ACTIVE(oldheader, now) || !EXISTS(oldheader)))
{
qpcache_hit(qpdb, oldheader);
@ -2781,7 +2786,7 @@ add(qpcache_t *qpdb, qpcnode_t *qpnode, dns_slabheader_t *newheader,
if (ACTIVE(oldheader, now) &&
oldheader->typepair == DNS_TYPEPAIR(dns_rdatatype_ns) &&
EXISTS(oldheader) && EXISTS(newheader) &&
oldheader->trust >= newheader->trust &&
newheader->trust < oldtrust &&
oldheader->expire < newheader->expire &&
dns_rdataslab_equalx(
oldheader, newheader, qpdb->common.rdclass,
@ -2815,14 +2820,14 @@ add(qpcache_t *qpdb, qpcnode_t *qpnode, dns_slabheader_t *newheader,
}
/*
* If we will be replacing a NS RRset force its TTL
* If we will be replacing an NS RRset, force its TTL
* to be no more than the current NS RRset's TTL. This
* ensures the delegations that are withdrawn are honoured.
*/
if (ACTIVE(oldheader, now) &&
oldheader->typepair == DNS_TYPEPAIR(dns_rdatatype_ns) &&
EXISTS(oldheader) && EXISTS(newheader) &&
oldheader->trust <= newheader->trust)
newheader->trust > oldtrust)
{
if (newheader->expire > oldheader->expire) {
if (ZEROTTL(oldheader)) {
@ -2841,7 +2846,7 @@ add(qpcache_t *qpdb, qpcnode_t *qpnode, dns_slabheader_t *newheader,
oldheader->typepair ==
DNS_SIGTYPEPAIR(dns_rdatatype_ds)) &&
EXISTS(oldheader) && EXISTS(newheader) &&
oldheader->trust >= newheader->trust &&
newheader->trust < oldtrust &&
oldheader->expire < newheader->expire &&
dns_rdataslab_equal(oldheader, newheader))
{

4
lib/dns/qpzone.c
View file

@ -981,7 +981,7 @@ bindrdataset(qpzonedb_t *qpdb, qpznode_t *node, dns_slabheader_t *header,
rdataset->type = DNS_TYPEPAIR_TYPE(header->typepair);
rdataset->covers = DNS_TYPEPAIR_COVERS(header->typepair);
rdataset->ttl = header->ttl;
rdataset->trust = header->trust;
rdataset->trust = atomic_load(&header->trust);
if (OPTOUT(header)) {
rdataset->attributes.optout = true;
@ -2137,7 +2137,7 @@ loading_addrdataset(void *arg, const dns_name_t *name,
dns_slabheader_reset(newheader, (dns_dbnode_t *)node);
newheader->ttl = rdataset->ttl;
newheader->trust = rdataset->trust;
atomic_store(&newheader->trust, rdataset->trust);
newheader->serial = 1;
dns_slabheader_setownercase(newheader, name);

7
lib/dns/rdataslab.c
View file

@ -1123,9 +1123,8 @@ static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
dns_slabheader_t *header = dns_rdataset_getheader(rdataset);
dns_db_locknode(header->node, isc_rwlocktype_write);
header->trust = rdataset->trust = trust;
dns_db_unlocknode(header->node, isc_rwlocktype_write);
rdataset->trust = trust;
atomic_store(&header->trust, trust);
}
static void
@ -1139,9 +1138,7 @@ static void
rdataset_clearprefetch(dns_rdataset_t *rdataset) {
dns_slabheader_t *header = dns_rdataset_getheader(rdataset);
dns_db_locknode(header->node, isc_rwlocktype_write);
DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_PREFETCH);
dns_db_unlocknode(header->node, isc_rwlocktype_write);
}
static void