Re: [PATCH mptcp-net v2 2/2] selftests: mptcp: join: re-add the initial subflow endp with fullmesh

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] selftests: mptcp: undefined init_nftables() breaks endpoint_tests()
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commit bc814fecc7de467b22c281bbf58a319ea166e5a2
Author: Abdul Wasey <w453y.me@gmail.com>

selftests: mptcp: join: re-add the initial subflow endp with fullmesh

This commit adds two selftests to endpoint_tests() in mptcp_join.sh to
verify deleting and re-adding the endpoint of the initial subflow when the
fullmesh flag is set, both normally and after the initial subflow is reset.

> diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> index 18ce7136a2b0e..0fa69aa2e9b80 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> @@ -4445,6 +4445,70 @@ endpoint_tests()
[ ... ]
> +	# same, but the initial subflow is reset before removing its endpoint
> +	if reset_with_events "delete and re-add, fullmesh, after reset" &&
> +	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
> +		pm_nl_set_limits $ns1 0 2
> +		pm_nl_set_limits $ns2 0 2
> +		pm_nl_add_endpoint $ns2 10.0.1.2 id 1 dev ns2eth1 flags subflow,fullmesh
> +		pm_nl_add_endpoint $ns2 10.0.2.2 id 2 dev ns2eth2 flags subflow,fullmesh
> +		{ timeout_test=120 test_linkfail=128 speed=5 \
> +			run_tests $ns1 $ns2 10.0.1.1 & } 2>/dev/null
> +		local tests_pid=$!
> +
> +		wait_event ns2 MPTCP_LIB_EVENT_ESTABLISHED 1
> +		wait_mpj 1
> +		chk_subflow_nr "before reset" 2
> +
> +		init_nftables
> +		if ip netns exec "${ns1}" nft add rule ip filter INPUT \
> +				ip saddr "10.0.1.2" meta l4proto tcp \
> +				reject with tcp reset; then
> +			wait_event ns2 MPTCP_LIB_EVENT_SUB_CLOSED 1
> +			ip netns exec "${ns1}" nft flush chain ip filter INPUT
> +
> +			pm_nl_del_endpoint $ns2 1 10.0.1.2
> +			pm_nl_add_endpoint $ns2 10.0.1.2 id 1 dev ns2eth1 flags subflow,fullmesh
> +			wait_mpj 2
> +			chk_mptcp_info subflows 2 subflows 2
> +		fi
> +
> +		mptcp_lib_kill_group_wait $tests_pid
> +		kill_events_pids
> +
> +		chk_join_nr 2 2 2
> +	fi

[Severity: Medium]
Where is init_nftables defined? It does not appear to exist in
tools/testing/selftests/net/mptcp/mptcp_join.sh, mptcp_lib.sh, or
net/lib.sh, so calling it here produces "init_nftables: command not found".

Because the ip filter table and INPUT chain are never initialized in
${ns1} (which was freshly created via reset_with_events() ->
init_partial()), the subsequent "nft add rule ip filter INPUT ..." command
also fails with "No such file or directory".

That causes the if block to be skipped without resetting the subflow or
deleting and re-adding endpoint 1, and then chk_join_nr 2 2 2 fails
unconditionally because only 1 MP_JOIN occurred.

Should this use ${iptables} instead, matching how userspace_tests() in
tools/testing/selftests/net/mptcp/mptcp_join.sh injects TCP resets:

		if ip netns exec "${ns1}" ${iptables} -A INPUT -s "10.0.1.2" \
		      -p tcp --tcp-option 30 -j REJECT --reject-with tcp-reset &&

> +
>  	# remove and re-add
>  	if reset_with_events "delete re-add signal" &&
>  	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then

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Sashiko AI review · https://sashiko.dev/#/patchset/20261019180306.382039-1-w453y.me@gmail.com?part=2