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Currently sk_rethink_txhash() changes the socket's txhash on RTO, but the cached route is reused and the new hash is not propagated into the ECMP path selection logic. This series adds sk_dst_reset() alongside sk_rethink_txhash() to force a fresh route lookup, and sets fl6->mp_hash from sk_txhash so fib6_select_path() picks a path based on the new hash. Three selftest scenarios verify the behavior: SYN retransmission, SYN/ACK retransmission (server-side), and midstream RTO on an established connection. Changes since v1: - Use tcp_rsk(req)->txhash instead of jhash_1word(req->num_retrans, ...) for ECMP path selection in inet6_csk_route_req(), making the request socket path consistent with the established socket path (Eric Dumazet) - Add comments explaining the >> 1 shift for 31-bit mp_hash range - Add comment explaining the ir_iif update rationale in tcp_check_req() - Use socat -u (unidirectional) in selftest to avoid SIGPIPE race - Increase tcp_syn_retries and tcp_syn_linear_timeouts to 25 for better rehash coverage; add tcp_synack_retries=10 on the server Neil Spring (2): tcp: rehash onto different ECMP path on retransmit timeout selftests: net: add ECMP rehash test net/ipv4/tcp_input.c | 4 +- net/ipv4/tcp_minisocks.c | 13 + net/ipv4/tcp_plb.c | 1 + net/ipv4/tcp_timer.c | 1 + net/ipv6/inet6_connection_sock.c | 11 + tools/testing/selftests/net/Makefile | 1 + tools/testing/selftests/net/ecmp_rehash.sh | 361 +++++++++++++++++++++ 7 files changed, 391 insertions(+), 1 deletion(-) create mode 100755 tools/testing/selftests/net/ecmp_rehash.sh -- 2.52.0