Remove resolver.c:maybe_destroy()

After refactoring of `validated()`, the `maybe_destroy()` function is
no longer expected to actually destroy the fetch context when it is
being called, so effectively it only ensures that the validators are
canceled when the context has no more queries and pending events, but
that is redundant, because `maybe_destroy()` `REQUIRE`s that the context
should be in the shutting down state, and the function which sets that
state is already canceling the validators in its own turn.

As a failsafe, to make sure that no validators will be created after
`fctx_doshutdown()` is called, add an early return from `valcreate()` if
the context is in the shutting down state.

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index e8899d2457217d4ab033e51d63e5ebf62c1fc30c..15297024c0e80123593eec1dd26975bf5e6f3321 100644 (file)
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -641,8 +641,6 @@ ncache_adderesult(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
                  dns_rdataset_t *ardataset, isc_result_t *eresultp);
 static void
 validated(isc_task_t *task, isc_event_t *event);
-static bool
-maybe_destroy(fetchctx_t *fctx, bool locked);
 static void
 add_bad(fetchctx_t *fctx, dns_message_t *rmessage, dns_adbaddrinfo_t *addrinfo,
        isc_result_t reason, badnstype_t badtype);
@@ -902,14 +900,16 @@ valcreate(fetchctx_t *fctx, dns_message_t *message, dns_adbaddrinfo_t *addrinfo,
          dns_rdataset_t *sigrdataset, unsigned int valoptions,
          isc_task_t *task) {
        dns_validator_t *validator = NULL;
-       dns_valarg_t *valarg;
+       dns_valarg_t *valarg = NULL;
        isc_result_t result;
 
+       if (SHUTTINGDOWN(fctx)) {
+               return (ISC_R_SHUTTINGDOWN);
+       }
+
        valarg = isc_mem_get(fctx->mctx, sizeof(*valarg));
+       *valarg = (dns_valarg_t){ .fctx = fctx, .addrinfo = addrinfo };
 
-       valarg->fctx = fctx;
-       valarg->addrinfo = addrinfo;
-       valarg->message = NULL;
        dns_message_attach(message, &valarg->message);
 
        if (!ISC_LIST_EMPTY(fctx->validators)) {
@@ -4434,7 +4434,6 @@ resume_qmin(isc_task_t *task, isc_event_t *event) {
 
        LOCK(&res->buckets[bucketnum].lock);
        if (SHUTTINGDOWN(fctx)) {
-               maybe_destroy(fctx, true);
                UNLOCK(&res->buckets[bucketnum].lock);
                goto cleanup;
        }
@@ -5679,58 +5678,6 @@ clone_results(fetchctx_t *fctx) {
 #define CHASE(r)      (((r)->attributes & DNS_RDATASETATTR_CHASE) != 0)
 #define CHECKNAMES(r) (((r)->attributes & DNS_RDATASETATTR_CHECKNAMES) != 0)
 
-/*
- * Destroy '*fctx' if it is ready to be destroyed (i.e., if it has
- * no references and is no longer waiting for any events).
- *
- * Requires:
- *      '*fctx' is shutting down.
- *
- * Returns:
- *     true if the resolver is exiting and this is the last fctx in the bucket.
- */
-static bool
-maybe_destroy(fetchctx_t *fctx, bool locked) {
-       unsigned int bucketnum;
-       bool bucket_empty = false;
-       dns_resolver_t *res = fctx->res;
-       dns_validator_t *validator, *next_validator;
-       bool dodestroy = false;
-
-       bucketnum = fctx->bucketnum;
-       if (!locked) {
-               LOCK(&res->buckets[bucketnum].lock);
-       }
-
-       REQUIRE(SHUTTINGDOWN(fctx));
-
-       if (fctx->pending != 0 || fctx->nqueries != 0) {
-               goto unlock;
-       }
-
-       for (validator = ISC_LIST_HEAD(fctx->validators); validator != NULL;
-            validator = next_validator)
-       {
-               next_validator = ISC_LIST_NEXT(validator, link);
-               dns_validator_cancel(validator);
-       }
-
-       if (isc_refcount_current(&fctx->references) == 0 &&
-           ISC_LIST_EMPTY(fctx->validators))
-       {
-               bucket_empty = fctx_unlink(fctx);
-               dodestroy = true;
-       }
-unlock:
-       if (!locked) {
-               UNLOCK(&res->buckets[bucketnum].lock);
-       }
-       if (dodestroy) {
-               fctx_destroy(fctx);
-       }
-       return (bucket_empty);
-}
-
 /*
  * The validator has finished.
  */
@@ -5807,12 +5754,9 @@ validated(isc_task_t *task, isc_event_t *event) {
        sentresponse = ((fctx->options & DNS_FETCHOPT_NOVALIDATE) != 0);
 
        /*
-        * If shutting down, ignore the results.  Check to see if we're
-        * done waiting for validator completions and ADB pending events; if
-        * so, destroy the fctx.
+        * If shutting down, ignore the results.
         */
        if (SHUTTINGDOWN(fctx) && !sentresponse) {
-               maybe_destroy(fctx, true);
                UNLOCK(&res->buckets[bucketnum].lock);
                goto cleanup_event;
        }
@@ -6052,9 +5996,6 @@ validated(isc_task_t *task, isc_event_t *event) {
                 * the data, destroy now.
                 */
                dns_db_detachnode(fctx->cache, &node);
-               if (SHUTTINGDOWN(fctx)) {
-                       maybe_destroy(fctx, true);
-               }
                UNLOCK(&res->buckets[bucketnum].lock);
                goto cleanup_event;
        }