From 58d8baa70172bb9862276ac5f542248c88d3faf4 Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Wed, 24 Jun 2020 18:48:14 +0200
Subject: [PATCH] JSON: Improve performance of json_events_cb()

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1835300
Upstream Status: nftables commit c96c7da272e33

commit c96c7da272e33a34770c4de4e3e50f7ed264672e
Author: Phil Sutter <phil@nwl.cc>
Date:   Wed May 13 16:29:51 2020 +0200

    JSON: Improve performance of json_events_cb()

    The function tries to insert handles into JSON input for echo option.
    Yet there may be nothing to do if the given netlink message doesn't
    contain a handle, e.g. if it is an 'add element' command. Calling
    seqnum_to_json() is pointless overhead in that case, and if input is
    large this overhead is significant. Better wait with that call until
    after checking if the message is relevant at all.

    Signed-off-by: Phil Sutter <phil@nwl.cc>
    Acked-by: Eric Garver <eric@garver.life>
---
 src/parser_json.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/parser_json.c b/src/parser_json.c
index c48faa8..ce8e566 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -3845,12 +3845,15 @@ static uint64_t handle_from_nlmsg(const struct nlmsghdr *nlh)
 }
 int json_events_cb(const struct nlmsghdr *nlh, struct netlink_mon_handler *monh)
 {
-	json_t *tmp, *json = seqnum_to_json(nlh->nlmsg_seq);
 	uint64_t handle = handle_from_nlmsg(nlh);
+	json_t *tmp, *json;
 	void *iter;
 
-	/* might be anonymous set, ignore message */
-	if (!json || !handle)
+	if (!handle)
+		return MNL_CB_OK;
+
+	json = seqnum_to_json(nlh->nlmsg_seq);
+	if (!json)
 		return MNL_CB_OK;
 
 	tmp = json_object_get(json, "add");
-- 
2.31.1