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Fix the statistic counter underflow in ns_client_t

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In case of normal fetch, the .recursionquota is attached and
ns_statscounter_recursclients is incremented when the fetch is created.  Then
the .recursionquota is detached and the counter decremented in the
fetch_callback().

In case of prefetch or rpzfetch, the quota is attached, but the counter is not
incremented.  When we reach the soft-quota, the function returns early but don't
detach from the quota, and it gets destroyed during the ns_client_endrequest(),
so no memory was leaked.

But because the ns_statscounter_recursclients is only incremented during the
normal fetch the counter would be incorrectly decremented on two occassions:

1) When we reached the softquota, because the quota was not properly detached
2) When the prefetch or rpzfetch was cancelled mid-flight and the callback
   function was never called.
This commit is contained in:
Ondřej Surý 2020-03-26 10:57:38 +01:00 committed by Ondřej Surý
parent 26842ac25c
commit 78886d4bed
2 changed files with 17 additions and 2 deletions
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6
lib/ns/client.c
View File

@ -235,8 +235,10 @@ ns_client_endrequest(ns_client_t *client) {
*/
if (client->recursionquota != NULL) {
isc_quota_detach(&client->recursionquota);
ns_stats_decrement(client->sctx->nsstats,
ns_statscounter_recursclients);
if (client->query.prefetch == NULL) {
ns_stats_decrement(client->sctx->nsstats,
ns_statscounter_recursclients);
}
}
/*

13
lib/ns/query.c
View File

@ -2463,6 +2463,13 @@ prefetch_done(isc_task_t *task, isc_event_t *event) {
}
UNLOCK(&client->query.fetchlock);
/*
* We're done prefetching, detach from quota.
*/
if (client->recursionquota != NULL) {
isc_quota_detach(&client->recursionquota);
}
free_devent(client, &event, &devent);
isc_nmhandle_unref(client->handle);
}
@ -2488,6 +2495,9 @@ query_prefetch(ns_client_t *client, dns_name_t *qname,
if (client->recursionquota == NULL) {
result = isc_quota_attach(&client->sctx->recursionquota,
&client->recursionquota);
if (result == ISC_R_SOFTQUOTA) {
isc_quota_detach(&client->recursionquota);
}
if (result != ISC_R_SUCCESS) {
return;
}
@ -2698,6 +2708,9 @@ query_rpzfetch(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t type) {
if (client->recursionquota == NULL) {
result = isc_quota_attach(&client->sctx->recursionquota,
&client->recursionquota);
if (result == ISC_R_SOFTQUOTA) {
isc_quota_detach(&client->recursionquota);
}
if (result != ISC_R_SUCCESS) {
return;
}