selftests: rtnetlink: print device info on preferred_lft test failure

Even with slowwait used to avoid system sleep in the preferred_lft test,
failures can still occur after long runtimes.

Print the device address info when the test fails to provide better
troubleshooting data.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20250819074749.388064-1-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 d6c00efeb66423be75ebb6bd55f850f0623f3e97..91b0f6cae04dbd9b247cd8515e729e759c49b3c8 100755 (executable)
--- a/tools/testing/selftests/net/rtnetlink.sh
+++ b/tools/testing/selftests/net/rtnetlink.sh
@@ -313,6 +313,8 @@ kci_test_addrlft()
 
        slowwait 5 check_addr_not_exist "$devdummy" "10.23.11."
        if [ $? -eq 1 ]; then
+               # troubleshoot the reason for our failure
+               run_cmd ip addr show dev "$devdummy"
                check_err 1
                end_test "FAIL: preferred_lft addresses remaining"
                return