Re: [PATCH net v1 2/2] selftest: net: Add test for TCP flow failover with ECMP routes.

[Ido Schimmel <idosch@nvidia.com>]

On Mon, Apr 27, 2026 at 10:42:23PM +0000, Sagarika Sharma wrote:
> From: Kuniyuki Iwashima <kuniyu@google.com>
> 
> Without the previous commit, TCP failed to switch to alternative
> IPv6 routes immediately upon carrier loss.
> 
> It would persist with the dead route until reaching the threshold
> net.ipv4.tcp_retries1, leading to unnecessary delays in failover.
> 
> Let's add a selftest for this scenario to ensure TCP fails over
> immediately upon a carrier loss event.
> 
> Before:
>   TEST: TCP IPv4 failover                                             [ OK ]
>   TEST: TCP IPv6 failover                                             [FAIL]
> 
> After:
>   TEST: TCP IPv4 failover                                             [ OK ]
>   TEST: TCP IPv6 failover                                             [ OK ]
> 
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> Signed-off-by: Sagarika Sharma <sharmasagarika@google.com>

Thanks for the test. LGTM. A couple of nits below.

[...]

> diff --git a/tools/testing/selftests/net/tcp_ecmp_failover.sh b/tools/testing/selftests/net/tcp_ecmp_failover.sh
> new file mode 100755
> index 000000000000..f857d5db84d8
> --- /dev/null
> +++ b/tools/testing/selftests/net/tcp_ecmp_failover.sh

[...]

> +
> +test_ipv4
> +test_ipv6

Maybe squash something like [1]? I ran the test without the first patch
and I get:

# ./tcp_ecmp_failover.sh 
TEST: TCP IPv4 failover                                             [ OK ]
TEST: TCP IPv6 failover                                             [FAIL]
# echo $?
0

[1]
diff --git a/tools/testing/selftests/net/tcp_ecmp_failover.sh b/tools/testing/selftests/net/tcp_ecmp_failover.sh
index f857d5db84d8..8b7a2d82c442 100755
--- a/tools/testing/selftests/net/tcp_ecmp_failover.sh
+++ b/tools/testing/selftests/net/tcp_ecmp_failover.sh
@@ -205,5 +205,10 @@ test_ipv6()
 	cleanup
 }
 
+require_command socat
+require_command tcpdump
+
 test_ipv4
 test_ipv6
+
+exit "$EXIT_STATUS"