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Yuri Benditovich 622479d100 net: change maximum number of UDP segments to 128 
[ Upstream commit 1382e3b6a3 ]

The commit fc8b2a6194
("net: more strict VIRTIO_NET_HDR_GSO_UDP_L4 validation")
adds check of potential number of UDP segments vs
UDP_MAX_SEGMENTS in linux/virtio_net.h.
After this change certification test of USO guest-to-guest
transmit on Windows driver for virtio-net device fails,
for example with packet size of ~64K and mss of 536 bytes.
In general the USO should not be more restrictive than TSO.
Indeed, in case of unreasonably small mss a lot of segments
can cause queue overflow and packet loss on the destination.
Limit of 128 segments is good for any practical purpose,
with minimal meaningful mss of 536 the maximal UDP packet will
be divided to ~120 segments.
The number of segments for UDP packets is validated vs
UDP_MAX_SEGMENTS also in udp.c (v4,v6), this does not affect
quest-to-guest path but does affect packets sent to host, for
example.
It is important to mention that UDP_MAX_SEGMENTS is kernel-only
define and not available to user mode socket applications.
In order to request MSS smaller than MTU the applications
just uses setsockopt with SOL_UDP and UDP_SEGMENT and there is
no limitations on socket API level.

Fixes: fc8b2a6194 ("net: more strict VIRTIO_NET_HDR_GSO_UDP_L4 validation")
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-04-27 17:11:32 +02:00
..
crypto/chacha20-s390 tools/testing/crypto: Use vzalloc instead of vmalloc+memset 2022-07-05 14:46:36 +02:00
cxl cxl: Add cxl_num_decoders_committed() usage to cxl_test 2024-01-10 17:17:02 +01:00
fault-injection docs: fault-injection: convert docs to ReST and rename to *.rst 2019-06-14 14:21:07 -06:00
ktest ktest: force $buildonly = 1 for 'make_warnings_file' test type 2024-04-13 13:07:37 +02:00
kunit kunit: tool: fix parsing of test attributes 2024-02-05 20:14:15 +00:00
memblock memblock tests: fix warning ‘struct seq_file’ declared inside parameter list 2023-09-14 10:51:28 +03:00
nvdimm tools/testing/nvdimm: Drop empty platform remove function 2023-06-07 13:30:21 -07:00
radix-tree maple_tree: do not preallocate nodes for slot stores 2024-01-05 15:19:43 +01:00
scatterlist tools/testing/scatterlist: add missing defines 2022-01-30 09:56:58 +02:00
selftests net: change maximum number of UDP segments to 128 2024-04-27 17:11:32 +02:00
vsock vsock/test: fix SEQPACKET message bounds test 2023-12-03 07:33:05 +01:00