[PATCH net] selftests: net: wait for receiver startup in so_txtime.sh

[Paolo Abeni]

The mentioned test is failing in slow environments:

  # SO_TXTIME ipv4 clock monotonic
  # ./so_txtime: recv: timeout: Resource temporarily unavailable
  not ok 1 selftests: net: so_txtime.sh # exit=1

The receiver is started in background and the sender could end-up
transmitting the packet before the receiver is ready, so that the
later recv times out.

Address the issue explcitly waiting for the socket being bound to
the relevant port.

Fixes: af5136f95045 ("selftests/net: SO_TXTIME with ETF and FQ")
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
Note that to really cope with slow env the mentioned self-tests also
need net-next commit c41dfb0dfbec ("selftests/net: ignore timing
errors in so_txtime if KSFT_MACHINE_SLOW"), so this could be applied to
net-next, too
---
 tools/testing/selftests/net/so_txtime.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/net/so_txtime.sh 
b/tools/testing/selftests/net/so_txtime.sh
index 3f06f4d286a9..ade0e5755099 100755
--- a/tools/testing/selftests/net/so_txtime.sh
+++ b/tools/testing/selftests/net/so_txtime.sh
@@ -5,6 +5,8 @@
 
 set -e
 
+source net_helper.sh
+
 readonly DEV="veth0"
 readonly BIN="./so_txtime"
 
@@ -51,13 +53,16 @@ do_test() {
        local readonly CLOCK="$2"
        local readonly TXARGS="$3"
        local readonly RXARGS="$4"
+       local PROTO
 
        if [[ "${IP}" == "4" ]]; then
                local readonly SADDR="${SADDR4}"
                local readonly DADDR="${DADDR4}"
+               PROTO=udp
        elif [[ "${IP}" == "6" ]]; then
                local readonly SADDR="${SADDR6}"
                local readonly DADDR="${DADDR6}"
+               PROTO=udp6
        else
                echo "Invalid IP version ${IP}"
                exit 1
@@ -65,6 +70,7 @@ do_test() {
 
        local readonly START="$(date +%s%N --date="+ 0.1 seconds")"
        ip netns exec "${NS2}" "${BIN}" -"${IP}" -c "${CLOCK}" -t "${START}" -S 
"${SADDR}" -D "${DADDR}" "${RXARGS}" -r &
+       wait_local_port_listen "${NS2}" 8000 "${PROTO}"
        ip netns exec "${NS1}" "${BIN}" -"${IP}" -c "${CLOCK}" -t "${START}" -S 
"${SADDR}" -D "${DADDR}" "${TXARGS}"
        wait "$!"
 }
-- 
2.43.0