cache-size: fix cache size value issue.

src/dns_conf.c

@@ -5936,7 +5936,7 @@ static struct config_item _config_item[] = {
 	CONF_CUSTOM("nftset-no-speed", _config_nftset_no_speed, NULL),
 	CONF_CUSTOM("speed-check-mode", _config_speed_check_mode, NULL),
 	CONF_INT("tcp-idle-time", &dns_conf_tcp_idle_time, 0, 3600),
-	CONF_SSIZE("cache-size", &dns_conf_cachesize, 0, CONF_INT_MAX),
+	CONF_SSIZE("cache-size", &dns_conf_cachesize, -1, CONF_INT_MAX),
 	CONF_CUSTOM("cache-file", _config_option_parser_filepath, (char *)&dns_conf_cache_file),
 	CONF_YESNO("cache-persist", &dns_conf_cache_persist),
 	CONF_INT("cache-checkpoint-time", &dns_conf_cache_checkpoint_time, 0, 3600 * 24 * 7),

src/lib/conf.c

@@ -233,10 +233,6 @@ int conf_ssize(const char *item, void *data, int argc, char *argv[])
 	}
 
 	num = atoi(value);
-	if (num < 0) {
-		return -1;
-	}
-
 	size = num * base;
 	if (size > item_size->max) {
 		size = item_size->max;