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Don't expire fresh ADB names and entries

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The overmem cleaning in ADB could become overzealous and clean fresh ADB
names and entries.  Add a safety check to not clean any ADB names and
entries that are below ADB_CACHE_MINIMUM threshold.

(cherry picked from commit 0b661b6f95)
This commit is contained in:
Ondřej Surý 2022-12-13 14:32:19 +01:00
parent ecde82689e
commit 146f93ff46
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
1 changed files with 22 additions and 10 deletions
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32
lib/dns/adb.c
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@ -324,7 +324,7 @@ inc_adb_erefcnt(dns_adb_t *);
static void
inc_entry_refcnt(dns_adb_t *, dns_adbentry_t *, bool);
static bool
dec_entry_refcnt(dns_adb_t *, bool, dns_adbentry_t *, bool);
dec_entry_refcnt(dns_adb_t *, bool, dns_adbentry_t *, bool, isc_stdtime_t);
static void
violate_locking_hierarchy(isc_mutex_t *, isc_mutex_t *);
static bool
@ -1372,7 +1372,8 @@ clean_namehooks(dns_adb_t *adb, dns_adbnamehooklist_t *namehooks) {
}
entry->nh--;
result = dec_entry_refcnt(adb, overmem, entry, false);
result = dec_entry_refcnt(adb, overmem, entry, false,
INT_MAX);
}
/*
@ -1648,10 +1649,10 @@ inc_entry_refcnt(dns_adb_t *adb, dns_adbentry_t *entry, bool lock) {
}
static bool
dec_entry_refcnt(dns_adb_t *adb, bool overmem, dns_adbentry_t *entry,
bool lock) {
dec_entry_refcnt(dns_adb_t *adb, bool overmem, dns_adbentry_t *entry, bool lock,
isc_stdtime_t now) {
int bucket;
bool destroy_entry;
bool destroy_entry = false;
bool result = false;
bucket = entry->lock_bucket;
@ -1663,9 +1664,9 @@ dec_entry_refcnt(dns_adb_t *adb, bool overmem, dns_adbentry_t *entry,
INSIST(entry->refcnt > 0);
entry->refcnt--;
destroy_entry = false;
if (entry->refcnt == 0 &&
(adb->entry_sd[bucket] || entry->expires == 0 || overmem ||
(adb->entry_sd[bucket] || entry->expires == 0 ||
(overmem && entry->expires + ADB_CACHE_MINIMUM < now) ||
(entry->flags & ENTRY_IS_DEAD) != 0))
{
destroy_entry = true;
@ -2370,6 +2371,14 @@ check_stale_name(dns_adb_t *adb, int bucket, isc_stdtime_t now) {
goto next;
}
/*
* Make sure that we are not purging ADB names that has been
* just created.
*/
if (victim->last_used + ADB_CACHE_MINIMUM >= now) {
break;
}
if (!NAME_FETCH(victim) &&
(overmem || victim->last_used + ADB_STALE_MARGIN <= now))
{
@ -3240,6 +3249,7 @@ dns_adb_destroyfind(dns_adbfind_t **findp) {
int bucket;
dns_adb_t *adb;
bool overmem;
isc_stdtime_t now;
REQUIRE(findp != NULL && DNS_ADBFIND_VALID(*findp));
find = *findp;
@ -3264,6 +3274,7 @@ dns_adb_destroyfind(dns_adbfind_t **findp) {
* Return the find to the memory pool, and decrement the adb's
* reference count.
*/
isc_stdtime_get(&now);
overmem = isc_mem_isovermem(adb->mctx);
ai = ISC_LIST_HEAD(find->list);
while (ai != NULL) {
@ -3271,7 +3282,8 @@ dns_adb_destroyfind(dns_adbfind_t **findp) {
entry = ai->entry;
ai->entry = NULL;
INSIST(DNS_ADBENTRY_VALID(entry));
RUNTIME_CHECK(!dec_entry_refcnt(adb, overmem, entry, true));
RUNTIME_CHECK(
!dec_entry_refcnt(adb, overmem, entry, true, now));
free_adbaddrinfo(adb, &ai);
ai = ISC_LIST_HEAD(find->list);
}
@ -4533,12 +4545,12 @@ dns_adb_freeaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **addrp) {
bucket = addr->entry->lock_bucket;
LOCK(&adb->entrylocks[bucket]);
isc_stdtime_get(&now);
if (entry->expires == 0) {
isc_stdtime_get(&now);
entry->expires = now + ADB_ENTRY_WINDOW;
}
want_check_exit = dec_entry_refcnt(adb, overmem, entry, false);
want_check_exit = dec_entry_refcnt(adb, overmem, entry, false, now);
UNLOCK(&adb->entrylocks[bucket]);