From: Simon Baatz <[email protected]> This test verifies - the sequence number checks using the maximum advertised window sequence number and - the logic for handling received data in tcp_data_queue()
for the cases: 1. The window is reduced to zero because of memory 2. The window grows again but still does not reach the originally advertised window Signed-off-by: Simon Baatz <[email protected]> --- .../net/packetdrill/tcp_rcv_wnd_shrink_nomem.pkt | 141 +++++++++++++++++++++ 1 file changed, 141 insertions(+) diff --git a/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_nomem.pkt b/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_nomem.pkt new file mode 100644 index 0000000000000000000000000000000000000000..8c30e231d7c82705f522f0e7bcdaffb9fb825974 --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_nomem.pkt @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0 +// When tcp_receive_window() < tcp_max_receive_window(), tcp_sequence() accepts +// packets that would be dropped under normal conditions (i.e. tcp_receive_window() +// equal to tcp_max_receive_window()). +// Test that such packets are handled as expected for RWIN == 0 and for RWIN > 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, [1000000], 4) = 0 + +0 bind(3, ..., ...) = 0 + +0 listen(3, 1) = 0 + + +0 < S 0:0(0) win 32792 <mss 1000,nop,nop,sackOK,nop,wscale 7> + +0 > S. 0:0(0) ack 1 win 65535 <mss 1460,nop,nop,sackOK,nop,wscale 4> + +0 < . 1:1(0) ack 1 win 257 + + +0 accept(3, ..., ...) = 4 + +// Put 1040000 bytes into the receive buffer + +0 < P. 1:65001(65000) ack 1 win 257 + * > . 1:1(0) ack 65001 + +0 < P. 65001:130001(65000) ack 1 win 257 + * > . 1:1(0) ack 130001 + +0 < P. 130001:195001(65000) ack 1 win 257 + * > . 1:1(0) ack 195001 + +0 < P. 195001:260001(65000) ack 1 win 257 + * > . 1:1(0) ack 260001 + +0 < P. 260001:325001(65000) ack 1 win 257 + * > . 1:1(0) ack 325001 + +0 < P. 325001:390001(65000) ack 1 win 257 + * > . 1:1(0) ack 390001 + +0 < P. 390001:455001(65000) ack 1 win 257 + * > . 1:1(0) ack 455001 + +0 < P. 455001:520001(65000) ack 1 win 257 + * > . 1:1(0) ack 520001 + +0 < P. 520001:585001(65000) ack 1 win 257 + * > . 1:1(0) ack 585001 + +0 < P. 585001:650001(65000) ack 1 win 257 + * > . 1:1(0) ack 650001 + +0 < P. 650001:715001(65000) ack 1 win 257 + * > . 1:1(0) ack 715001 + +0 < P. 715001:780001(65000) ack 1 win 257 + * > . 1:1(0) ack 780001 + +0 < P. 780001:845001(65000) ack 1 win 257 + * > . 1:1(0) ack 845001 + +0 < P. 845001:910001(65000) ack 1 win 257 + * > . 1:1(0) ack 910001 + +0 < P. 910001:975001(65000) ack 1 win 257 + * > . 1:1(0) ack 975001 + +0 < P. 975001:1040001(65000) ack 1 win 257 + * > . 1:1(0) ack 1040001 + +// Trigger an extreme memory squeeze by shrinking SO_RCVBUF + +0 setsockopt(4, SOL_SOCKET, SO_RCVBUF, [16000], 4) = 0 + + +0 < P. 1040001:1105001(65000) ack 1 win 257 + * > . 1:1(0) ack 1040001 win 0 +// Check LINUX_MIB_TCPRCVQDROP has been incremented + +0 `nstat -s | grep TcpExtTCPRcvQDrop| grep -q " 1 "` + +// RWIN == 0: rcv_wup = 1040001, rcv_wnd = 0, rcv_mwnd_seq > 1105001 (significantly larger, typically ~1970000) + +// Accept pure ack with seq in max adv. window + +0 write(4, ..., 1000) = 1000 + +0 > P. 1:1001(1000) ack 1040001 win 0 + +0 < . 1105001:1105001(0) ack 1001 win 257 + +// In order segment, in max adv. window -> drop (SKB_DROP_REASON_TCP_ZEROWINDOW) + +0 < P. 1040001:1041001(1000) ack 1001 win 257 + +0 > . 1001:1001(0) ack 1040001 win 0 +// Ooo partial segment, in max adv. window -> drop (SKB_DROP_REASON_TCP_ZEROWINDOW) + +0 < P. 1039001:1041001(2000) ack 1001 win 257 + +0 > . 1001:1001(0) ack 1040001 win 0 <nop,nop,sack 1039001:1040001> +// Check LINUX_MIB_TCPZEROWINDOWDROP has been incremented twice + +0 `nstat -s | grep TcpExtTCPZeroWindowDrop| grep -q " 2 "` + +// Ooo segment, in max adv. window -> drop (SKB_DROP_REASON_TCP_OVERWINDOW) + +0 < P. 1105001:1106001(1000) ack 1001 win 257 + +0 > . 1001:1001(0) ack 1040001 win 0 +// Ooo segment, beyond max adv. window -> drop (SKB_DROP_REASON_TCP_INVALID_SEQUENCE) + +0 < P. 2000001:2001001(1000) ack 1001 win 257 + +0 > . 1001:1001(0) ack 1040001 win 0 +// Check LINUX_MIB_BEYOND_WINDOW has been incremented twice + +0 `nstat -s | grep TcpExtBeyondWindow | grep -q " 2 "` + +// Read all data + +0 read(4, ..., 2000000) = 1040000 + * > . 1001:1001(0) ack 1040001 + +// RWIN > 0: rcv_wup = 1040001, 0 < rcv_wnd < 32000, rcv_mwnd_seq > 1105001 (significantly larger, typically ~1970000) + +// Accept pure ack with seq in max adv. window, beyond adv. window + +0 write(4, ..., 1000) = 1000 + +0 > P. 1001:2001(1000) ack 1040001 + +0 < . 1105001:1105001(0) ack 2001 win 257 + +// In order segment, in max adv. window, in adv. window -> accept +// Note: This also ensures that we cannot hit the empty queue exception in tcp_sequence() in the following tests + +0 < P. 1040001:1041001(1000) ack 2001 win 257 + * > . 2001:2001(0) ack 1041001 + +// Ooo partial segment, in adv. window -> accept + +0 < P. 1040001:1042001(2000) ack 2001 win 257 + +0 > . 2001:2001(0) ack 1042001 <nop,nop,sack 1040001:1041001> + +// Ooo segment, in max adv. window, beyond adv. window -> drop (SKB_DROP_REASON_TCP_OVERWINDOW) + +0 < P. 1105001:1106001(1000) ack 2001 win 257 + +0 > . 2001:2001(0) ack 1042001 +// Ooo segment, beyond max adv. window, beyond adv. window -> drop (SKB_DROP_REASON_TCP_INVALID_SEQUENCE) + +0 < P. 2000001:2001001(1000) ack 2001 win 257 + +0 > . 2001:2001(0) ack 1042001 +// Check LINUX_MIB_BEYOND_WINDOW has been incremented twice + +0 `nstat -s | grep TcpExtBeyondWindow | grep -q " 4 "` + +// Let's probe how much more data we can squeeze in, 2 * 10k should be ok + +0 < P. 1042001:1052001(10000) ack 2001 win 257 + * > . 2001:2001(0) ack 1052001 + +0 < P. 1052001:1062001(10000) ack 2001 win 257 + * > . 2001:2001(0) ack 1062001 + +// Ooo segment, in max adv. window, seq 152002 in adv. window, not enough buffer space -> drop, _no_ ack + +0 < P. 1062002:1072002(10000) ack 2001 win 257 +// Check LINUX_MIB_TCPOFODROP has been incremented + +.1 `nstat -s | grep TcpExtTCPOFODrop | grep -q " 1 "` + +// In order segment, in max adv. window, not enough buffer space -> drop + +0 < P. 1062001:1072001(10000) ack 2001 win 257 + +0 > . 2001:2001(0) ack 1062001 win 0 +// Check LINUX_MIB_TCPRCVQDROP has been incremented again + +0 `nstat -s | grep TcpExtTCPRcvQDrop | grep -q " 2 "` + +// Verify that our other counters did not change + +0 `nstat -s | grep TcpExtTCPZeroWindowDrop | grep -q " 2 "` + +0 `nstat -s | grep TcpExtBeyondWindow | grep -q " 4 "` -- 2.53.0
