ntuple off/on might be not enough to do it on all NICs.
Add a bunch of shell crap to explicitly remove the rules.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 tools/testing/selftests/net/ncdevmem.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/net/ncdevmem.c b/tools/testing/selftests/net/ncdevmem.c
index 645ef0bb63ec..ad6de8e0e97b 100644
--- a/tools/testing/selftests/net/ncdevmem.c
+++ b/tools/testing/selftests/net/ncdevmem.c
@@ -217,13 +217,18 @@ void validate_buffer(void *line, size_t size)
 
 static int reset_flow_steering(void)
 {
-	int ret = 0;
-
-	ret = run_command("sudo ethtool -K %s ntuple off >&2", ifname);
-	if (ret)
-		return ret;
-
-	return run_command("sudo ethtool -K %s ntuple on >&2", ifname);
+	/* Depending on the NIC, toggling ntuple off and on might not
+	 * be allowed. Additionally, attempting to delete existing filters
+	 * will fail if no filters are present. Therefore, do not enforce
+	 * the exit status.
+	 */
+
+	run_command("sudo ethtool -K %s ntuple off >&2", ifname);
+	run_command("sudo ethtool -K %s ntuple on >&2", ifname);
+	run_command(
+		"sudo ethtool -n %s | grep 'Filter:' | awk '{print $2}' | xargs -n1 ethtool -N %s delete >&2",
+		ifname, ifname);
+	return 0;
 }
 
 static int configure_headersplit(bool on)
-- 
2.47.0