cache: Optimize caching for 'list tables' command

No point in fetching anything other than existing tables from kernel:
'list tables' merely prints existing table names, no contents.

Also populate filter's family field to reduce overhead when listing
tables in one family with many tables in another one. It works without
further adjustments because nftnl_nlmsg_build_hdr() will use the value
for nfgen_family.

Reported-by: anton.khazan@gmail.com
Link: https://bugzilla.netfilter.org/show_bug.cgi?id=1735
Signed-off-by: Phil Sutter <phil@nwl.cc>

diff --git a/src/cache.c b/src/cache.c
index b7f46c001d6ebb5d6e5d11d8868348ad8e37aa97..97f50ccaf6ba161f79afcd2e8b60da68374ff356 100644 (file)
--- a/src/cache.c
+++ b/src/cache.c
@@ -203,8 +203,12 @@ static unsigned int evaluate_cache_list(struct nft_ctx *nft, struct cmd *cmd,
 {
        switch (cmd->obj) {
        case CMD_OBJ_TABLE:
-               if (filter && cmd->handle.table.name) {
+               if (filter)
                        filter->list.family = cmd->handle.family;
+               if (!cmd->handle.table.name) {
+                       flags |= NFT_CACHE_TABLE;
+                       break;
+               } else if (filter) {
                        filter->list.table = cmd->handle.table.name;
                }
                flags |= NFT_CACHE_FULL;