On 7/20/26 3:03 PM, David Marchand wrote:
> On Mon, 20 Jul 2026 at 12:48, Dmitry Mityugov via discuss
> <[email protected]> wrote:
>>
>> Hi,
>>
>> It seems that test 1262 ("ofproto-dpif - fragment handling -
>> reassembly") is flaky, and when run on an ARM machine and with
>> --enable-shared configure parameter, it almost always fails. It also
>> sometimes fails on x86 machines and on ARM machines without
>> --enable-shared. Running `make check TESTSUITEFLAGS=--recheck` usually
>> fixes these random failures.
>>
>> To reliably reproduce the problem, this command can be used, on an ARM
>> machine:
>>
>> make distclean ; ./boot.sh && ./configure --enable-shared && make -j9
>> && make check RECHECK=yes TESTSUITEFLAGS=-j8
>>
>> I used Orange Pi 6 Plus and Rock Pi 5b ARM machines to reproduce this,
>> with Arch Linux (kernel 7.x) and Armbian (kernel 6.18). I'm attaching
>> relevant files. Please let me know if I can help further.
>
> From the logs, we are missing a flow in the dump:
> -recirc(),in_port(90),packet_type(ns=0,id=0),eth(src=22:22:22:22:22:22),eth_type(0x0800),ipv4(src=2.2.2.2/248.0.0.0,proto=6,frag=first),
> packets:0, bytes:0, actions:ct(commit,zone=10),recirc()
>
>
> This flow is a consequence of receiving the first fragment:
> 2026-07-20T10:29:34.952Z|00121|unixctl|DBG|received request
> netdev-dummy/receive["p90","1111111111112222222222220800450001d4123420004006dead020202020101010100020001000000000000000050020000a9da00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"],
> id=0
>
> And the flow dump happens at:
> 2026-07-20T10:29:46.280Z|00393|unixctl|DBG|received request
> dpctl/dump-flows[], id=0
>
> So my guess is that the "first" flow expired after 10s, probably due
> to some external activity on the system running the test.
>
> Looking at my recent change, I lazily copied some printf that seems to
> take a long time.
Beside that, I think, the test should stop the time as well in the
beginning. Though this affects the stats reported on the flows,
which is likely a sign of a different race in this test as well.
Best regards, Ilya Maximets.
>
> Could you try this diff:
>
> $ git diff
> diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
> index 02b4a02be1..64d73f6734 100644
> --- a/tests/ofproto-dpif.at
> +++ b/tests/ofproto-dpif.at
> @@ -5489,7 +5489,7 @@ m4_define([GEN_IP_FRAGS],
> AT_CHECK([ovs-ofctl compose-packet --bare "${flow_first}"], [0], [stdout])
> hdr=$(cat stdout)
> ip_len=$(printf '%04x' $((20 + frag_len)))
> - payload=$(printf '0%.0s' $(seq $(( (frag_len - 20) * 2 ))))
> + payload=$(printf "%0$(( (frag_len - 20) * 2 ))d" 0)
> AT_CHECK([echo ${hdr}${payload} \
> | sed
> "s/^\(.\{32\}\).\{12\}\(.\{4\}\).\{4\}/\1${ip_len}12342000\2dead/"],
> [0], [stdout])
> @@ -5498,7 +5498,7 @@ m4_define([GEN_IP_FRAGS],
> AT_CHECK([ovs-ofctl compose-packet --bare "${flow_later}"], [0], [stdout])
> hdr=$(cat stdout)
> ip_len=$(printf '%04x' $((20 + frag_len)))
> - payload=$(printf '0%.0s' $(seq $(( frag_len * 2 ))))
> + payload=$(printf "%0$(( frag_len * 2 ))d" 0)
> for i in $(seq 1 61); do
> frag_off=$(printf '%04x' $((0x2000 + i * frag_len / 8)))
> AT_CHECK([echo ${hdr}${payload} \
> @@ -5508,7 +5508,7 @@ m4_define([GEN_IP_FRAGS],
> done
>
> ip_len=$(printf '%04x' $((40 + frag_len / 2)))
> - payload=$(printf '0%.0s' $(seq $((frag_len + 40))))
> + payload=$(printf "%0$((frag_len + 40))d" 0)
> frag_off=$(printf '%04x' $((62 * frag_len / 8)))
> AT_CHECK([echo ${hdr}${payload} \
> | sed
> "s/^\(.\{32\}\).\{12\}\(.\{4\}\).\{4\}/\1${ip_len}1234${frag_off}\2dead/"],
> @@ -5567,7 +5567,7 @@ dnl Make sure all four packets are counted
> properly in the coverage.
> AT_CHECK([ovs-appctl coverage/show | grep -c "^ipf.*total: 2"], [0], [2
> ])
>
> -zero1208=$(printf '0%.0s' $(seq 2416))
> +zero1208=$(printf '%02416d' 0)
> dnl Test that reassembled packets flow.
> AT_CHECK([ovs-appctl netdev-dummy/receive p90 "0021853763af
> 0026b98cb0f9 0800 4500 04c4 0002 2000 40 06 8ff7 ac11370d ac11370b dnl
> 0000 0001 00000000 00000000 50 10 8000 604c 0000 dnl
>
>
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