Due to the gro_sender sending data packets and FIN packets in very quick succession, these are received almost simultaneously by the gro_receiver. FIN packets are sometimes processed before the data packets leading to intermittent (~1/100) test failures.

This change adds a delay of 100ms before sending FIN packets in gro:tcp test to avoid the out-of-order delivery. The same mitigation already exists for the gro:ip test.

Fixes: 7d1575014a63 ("selftests/net: GRO coalesce test") Reviewed-by: Willem de Bruijn willemb@google.com Signed-off-by: Anubhav Singh anubhavsinggh@google.com --- Changes in v2: - Add 'Shuah Khan shuah@kernel.org' to the CC list.

tools/testing/selftests/net/gro.c | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c index 2b1d9f2b3e9e..3fa63bd85dea 100644 --- a/tools/testing/selftests/net/gro.c +++ b/tools/testing/selftests/net/gro.c @@ -989,6 +989,7 @@ static void check_recv_pkts(int fd, int *correct_payload,

static void gro_sender(void) { + const int fin_delay_us = 100 * 1000; static char fin_pkt[MAX_HDR_LEN]; struct sockaddr_ll daddr = {}; int txfd = -1; @@ -1032,15 +1033,22 @@ static void gro_sender(void) write_packet(txfd, fin_pkt, total_hdr_len, &daddr); } else if (strcmp(testname, "tcp") == 0) { send_changed_checksum(txfd, &daddr); + /* Adding sleep before sending FIN so that it is not + * received prior to other packets. + */ + usleep(fin_delay_us); write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

send_changed_seq(txfd, &daddr); + usleep(fin_delay_us); write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

send_changed_ts(txfd, &daddr); + usleep(fin_delay_us); write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

send_diff_opt(txfd, &daddr); + usleep(fin_delay_us); write_packet(txfd, fin_pkt, total_hdr_len, &daddr); } else if (strcmp(testname, "ip") == 0) { send_changed_ECN(txfd, &daddr);