selftests/bpf: fix race in test_tcp_rtt test

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There is a race in this test between receiving the ACK for the
single-byte packet sent in the test, and reading the values from the
map.

This patch fixes this by having the client wait until there are no more
unacknowledged packets.

Before:
for i in {1..1000}; do ../net/in_netns.sh ./test_tcp_rtt; \
done | grep -c PASSED
< trimmed error messages >
993

After:
for i in {1..10000}; do ../net/in_netns.sh ./test_tcp_rtt; \
done | grep -c PASSED
10000

Fixes: b55873984d ("selftests/bpf: test BPF_SOCK_OPS_RTT_CB")
Signed-off-by: Petar Penkov <ppenkov@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

...

This commit is contained in:

Petar Penkov 2019-08-16 10:08:25 -07:00 • committed by Daniel Borkmann

parent 929ffa6e9d

commit fae55527ac

1 changed files with 31 additions and 0 deletions

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tools/testing/selftests/bpf/test_tcp_rtt.c

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