lru_get_new *can* return NULL

... and that doesn't necessarily mean that malloc() failed.
We do *not* want to evict a heavy-hitter by an unfrequent element.

Note: even the implementation currently in master *did* return NULL,
so some parts of the code were just wrongly returning ENOMEM.

lib/cookies/lru_cache.c

@@ -62,11 +62,9 @@ int kr_cookie_lru_set(kr_cookie_lru_t *cache, const struct sockaddr *sa,
 	}
 
 	struct cookie_opt_data *cached = lru_get_new(cache, addr, addr_len);
-	if (!cached) {
-		return kr_error(ENOMEM);
+	if (cached) {
+		memcpy(cached->opt_data, opt, opt_size);
 	}
 
-	memcpy(cached->opt_data, opt, opt_size);
-
 	return kr_ok();
 }

lib/nsrep.c

@@ -260,7 +260,7 @@ int kr_nsrep_update_rtt(struct kr_nsrep *ns, const struct sockaddr *addr,
 	}
 	unsigned *cur = lru_get_new(cache, addr_in, addr_len);
 	if (!cur) {
-		return kr_error(ENOMEM);
+		return kr_ok();
 	}
 	/* Score limits */
 	if (score > KR_NS_MAX_SCORE) {
@@ -294,9 +294,8 @@ int kr_nsrep_update_rep(struct kr_nsrep *ns, unsigned reputation, kr_nsrep_lru_t
 	ns->reputation = reputation;
 	/* Store reputation in the LRU cache */
 	unsigned *cur = lru_get_new(cache, (const char *)ns->name, knot_dname_size(ns->name));
-	if (!cur) {
-		return kr_error(ENOMEM);
+	if (cur) {
+		*cur = reputation;
 	}
-	*cur = reputation;
 	return kr_ok();
 }

tests/test_lru.c

@@ -62,7 +62,9 @@ static void test_insert(void **state)
 
 	for (i = 0; i < dict_size; i++) {
 		int *data = lru_get_new(lru, dict[i], KEY_LEN(dict[i]));
-		assert_non_null(data);
+		if (!data) {
+			continue;
+		}
 		*data = i;
 		assert_true(*lru_get_try(lru, dict[i], KEY_LEN(dict[i])) == i);
 	}
@@ -83,7 +85,7 @@ static void test_eviction(void **state)
 		test_randstr(key, sizeof(key));
 		int *data = lru_get_new(lru, key, sizeof(key));
 		if (!data) {
-			assert_true(0);
+			continue;
 		}
 		*data = i;
 		if (*lru_get_try(lru, key, sizeof(key)) != i) {