selftests: rtnetlink: fix addrlft test flakiness on power-saving systems

Jakub reported that the rtnetlink test for the preferred lifetime of an
address has become quite flaky. The issue started appearing around the 6.16
merge window in May, and the test fails with:

    FAIL: preferred_lft addresses remaining

The flakiness might be related to power-saving behavior, as address
expiration is handled by a "power-efficient" workqueue.

To address this, use slowwait to check more frequently whether the address
still exists. This reduces the likelihood of the system entering a low-power
state during the test, improving reliability.

Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20250715043459.110523-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/rtnetlink.sh b/tools/testing/selftests/net/rtnetlink.sh
index 2e8243a65b5070290385f3edd8aa3da81f9935fe..49141254065cb3eebed25f4f36fb07d4fa68149f 100755 (executable)
--- a/tools/testing/selftests/net/rtnetlink.sh
+++ b/tools/testing/selftests/net/rtnetlink.sh
@@ -291,6 +291,17 @@ kci_test_route_get()
        end_test "PASS: route get"
 }
 
+check_addr_not_exist()
+{
+       dev=$1
+       addr=$2
+       if ip addr show dev $dev | grep -q $addr; then
+               return 1
+       else
+               return 0
+       fi
+}
+
 kci_test_addrlft()
 {
        for i in $(seq 10 100) ;do
@@ -298,9 +309,8 @@ kci_test_addrlft()
                run_cmd ip addr add 10.23.11.$i/32 dev "$devdummy" preferred_lft $lft valid_lft $((lft+1))
        done
 
-       sleep 5
-       run_cmd_grep_fail "10.23.11." ip addr show dev "$devdummy"
-       if [ $? -eq 0 ]; then
+       slowwait 5 check_addr_not_exist "$devdummy" "10.23.11."
+       if [ $? -eq 1 ]; then
                check_err 1
                end_test "FAIL: preferred_lft addresses remaining"
                return