selftests: rtnetlink.sh: remove esp4_offload after test

The esp4_offload module, loaded during IPsec offload tests, should
be reset to its default settings after testing.
Otherwise, leaving it enabled could unintentionally affect subsequence
test cases by keeping offload active.

Without this fix:
$ lsmod | grep offload; ./rtnetlink.sh -t kci_test_ipsec_offload ; lsmod | grep offload;
PASS: ipsec_offload
esp4_offload           12288  0
esp4                   32768  1 esp4_offload

With this fix:
$ lsmod | grep offload; ./rtnetlink.sh -t kci_test_ipsec_offload ; lsmod | grep offload;
PASS: ipsec_offload

Fixes: 2766a11 ("selftests: rtnetlink: add ipsec offload API test")
Signed-off-by: Xiumei Mu <[email protected]>
Reviewed-by: Shannon Nelson <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
Link: https://patch.msgid.link/6d3a1d777c4de4eb0ca94ced9e77be8d48c5b12f.1753415428.git.xmu@redhat.com
Signed-off-by: Jakub Kicinski <[email protected]>

Author: xmmu

tools/testing/selftests/net/rtnetlink.sh

@@ -720,6 +720,11 @@ kci_test_ipsec_offload()
 	sysfsf=$sysfsd/ipsec
 	sysfsnet=/sys/bus/netdevsim/devices/netdevsim0/net/
 	probed=false
+	esp4_offload_probed_default=false
+
+	if lsmod | grep -q esp4_offload; then
+		esp4_offload_probed_default=true
+	fi
 
 	if ! mount | grep -q debugfs; then
 		mount -t debugfs none /sys/kernel/debug/ &> /dev/null
@@ -813,6 +818,7 @@ EOF
 	fi
 
 	# clean up any leftovers
+	! "$esp4_offload_probed_default" && lsmod | grep -q esp4_offload && rmmod esp4_offload
 	echo 0 > /sys/bus/netdevsim/del_device
 	$probed && rmmod netdevsim