From: Simon Baatz <gmbnomis@gmail.com>

Commit 1cc93c48b5d7 ("selftests/net: packetdrill: remove tests for
tcp_rcv_*big") removed the test for the reverted commit 1d2fbaad7cd8
("tcp: stronger sk_rcvbuf checks") but also the one for commit
9ca48d616ed7 ("tcp: do not accept packets beyond window").

Restore the test with the necessary adaptation: expect a delayed ACK
instead of an immediate one, since tcp_can_ingest() does not fail
anymore for the last data packet.

Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
---
 .../net/packetdrill/tcp_rcv_big_endseq.pkt         | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/tools/testing/selftests/net/packetdrill/tcp_rcv_big_endseq.pkt b/tools/testing/selftests/net/packetdrill/tcp_rcv_big_endseq.pkt
new file mode 100644
index 0000000000000000000000000000000000000000..6c0f32c40f19be2a750fc9d69bbf64250cd7b525
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/tcp_rcv_big_endseq.pkt
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+
+--mss=1000
+
+`./defaults.sh`
+
+    0 `nstat -n`
+
+// Establish a connection.
+   +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+   +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [10000], 4) = 0
+   +0 bind(3, ..., ...) = 0
+   +0 listen(3, 1) = 0
+
+   +0 < S 0:0(0) win 32792 <mss 1000,nop,wscale 7>
+   +0 > S. 0:0(0) ack 1 <mss 1460,nop,wscale 0>
+  +.1 < . 1:1(0) ack 1 win 257
+
+  +0 accept(3, ..., ...) = 4
+
+  +0 < P. 1:4001(4000) ack 1 win 257
+  +0 > .  1:1(0) ack 4001 win 5000
+
+// packet in sequence : SKB_DROP_REASON_TCP_INVALID_END_SEQUENCE / LINUX_MIB_BEYOND_WINDOW
+  +0 < P. 4001:54001(50000) ack 1 win 257
+  +0 > .  1:1(0) ack 4001 win 5000
+
+// ooo packet. : SKB_DROP_REASON_TCP_INVALID_END_SEQUENCE / LINUX_MIB_BEYOND_WINDOW
+  +1 < P. 5001:55001(50000) ack 1 win 257
+  +0 > .  1:1(0) ack 4001 win 5000
+
+// SKB_DROP_REASON_TCP_INVALID_SEQUENCE / LINUX_MIB_BEYOND_WINDOW
+  +0 < P. 70001:80001(10000) ack 1 win 257
+  +0 > .  1:1(0) ack 4001 win 5000
+
+  +0 read(4, ..., 100000) = 4000
+
+// If queue is empty, accept a packet even if its end_seq is above wup + rcv_wnd
+  +0 < P. 4001:54001(50000) ack 1 win 257
+   * > .  1:1(0) ack 54001 win 0
+
+// Check LINUX_MIB_BEYOND_WINDOW has been incremented 3 times.
++0 `nstat | grep TcpExtBeyondWindow | grep -q " 3 "`

---
base-commit: 9439a661c2e80485406ce2c90b107ca17858382d
change-id: 20260228-tcp_rcv_big_endseq-c8f1e7914a7d

Best regards,
-- 
Simon Baatz <gmbnomis@gmail.com>

On Sun, 01 Mar 2026 09:41:33 +0100 Simon Baatz via B4 Relay wrote:
> Commit 1cc93c48b5d7 ("selftests/net: packetdrill: remove tests for
> tcp_rcv_*big") removed the test for the reverted commit 1d2fbaad7cd8
> ("tcp: stronger sk_rcvbuf checks") but also the one for commit
> 9ca48d616ed7 ("tcp: do not accept packets beyond window").

Sorry about that!