netdev - [PATCH net-next 3/5] selftests: mlxsw: sch_red_core: Sleep before querying queue depth

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <321dcf8b3e9a1f0766429c8cf3e3f1746f1bc375.1728316370.git.petrm@nvidia.com>
Date: Mon, 7 Oct 2024 18:26:07 +0200
From: Petr Machata <petrm@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, <netdev@...r.kernel.org>
CC: Amit Cohen <amcohen@...dia.com>, Ido Schimmel <idosch@...dia.com>,
	<linux-kselftest@...r.kernel.org>, Shuah Khan <shuah@...nel.org>, "Petr
 Machata" <petrm@...dia.com>, <mlxsw@...dia.com>
Subject: [PATCH net-next 3/5] selftests: mlxsw: sch_red_core: Sleep before querying queue depth

The qdisc stats are taken from the port's periodic HW stats, which are
updated once a second. We try to accommodate the latency by using busywait
in build_backlog().

The issue in that seems to be that when do_mark_test() builds the backlog,
it makes the decision whether to send more packets based on the first
instance of the queue depth stat exceeding the current value, when in fact
more traffic is on the way and the queue depth would increase further. This
leads to failures in TC 1 of mark-mirror test, where we see the following
failure:

TEST: TC 0: marked packets mirror'd                                 [ OK ]
TEST: TC 1: marked packets mirror'd                                 [FAIL]
        Spurious packets (1680 -> 2290) observed without buffer pressure

Fix by waiting for the full second before reading the queue depth for the
first time, to make sure it reflects all in-flight traffic.

Signed-off-by: Petr Machata <petrm@...dia.com>
Reviewed-by: Amit Cohen <amcohen@...dia.com>
---
 tools/testing/selftests/drivers/net/mlxsw/sch_red_core.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/drivers/net/mlxsw/sch_red_core.sh b/tools/testing/selftests/drivers/net/mlxsw/sch_red_core.sh
index a25a15eb6d31..b1ff395b3880 100644
--- a/tools/testing/selftests/drivers/net/mlxsw/sch_red_core.sh
+++ b/tools/testing/selftests/drivers/net/mlxsw/sch_red_core.sh
@@ -372,6 +372,7 @@ build_backlog()
 	local i=0

 	while :; do
+		sleep 1
 		local cur=$(busywait 1100 until_counter_is "> $cur" \
 					    get_qdisc_backlog $vlan)
 		local diff=$((size - cur))
-- 
2.45.0