Behavior untouched; each marker records a known gap and the intended
fix so the next visit doesn't rediscover it: transient zero-sent
sendmmsg errors drop a whole run; the non-vnet Poll queue lacks the
post-wake drain loop; recvmmsg controllen resets touch every entry;
cached handshake packets flush one syscall each; the routines clamp in
activate() would blackhole surplus REUSEPORT sockets if it ever became
reachable; darwin WriteBatch burst-drops on EWOULDBLOCK.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
- multi_coalesce/batch: the ordering contract now states what Flush
actually guarantees -- per-flow DATA order -- and names the two
shapes later data may legally overtake (pure ACKs by design, and
unparseable in-flow shapes as an accepted tradeoff).
- validVnetHdr claimed DATA_VALID makes the stack skip L4 checksum
verification; the tun write path ignores that bit entirely. What the
header buys is the absence of NEEDS_CSUM.
- tun_darwin Write said "only valid for single threaded use"; it is
concurrency-safe and concurrent callers exist.
- udp_coalesce eviction comment said "Seal it" but never sets sealed.
- recordCapability: note the gauges are process-global while the state
is per-socket (last writer wins).
- drop a stale tunReadBufSize reference.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
Every non-coalesceable in-flow packet evicted the flow's open slot, so
a bidirectional connection's inbound data run was broken by each peer
ACK interleaved into it, largely defeating coalescing on concurrent
upload+download. A bare acknowledgment (zero payload, nothing beyond
ACK|PSH|ECE) carries no ordering obligation toward the flow's data --
delivered late it is just a stale ACK the receiver ignores -- so it
can ride the lane as a passthrough without the evict, same as kernel
GRO, which doesn't flush held data on pure ACKs. SYN/FIN/RST/CWR keep
sealing.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
A slot that stays single-segment is byte-identical to the packet it
was seeded from, but flushSlot re-emitted it via WriteGSO with a
seeded pseudo-sum, forcing the kernel to software-checksum up to
~1400B that arrived with a perfectly valid checksum. Keep the borrowed
seed packet on the slot (valid until Flush per the Commit contract)
and emit it through the plain DATA_VALID path when numSeg is still 1
at flush time. appendPayload and mergeSlots only touch hdrBuf once
numSeg >= 2, so the raw bytes are pristine whenever the fast path
fires. This is every non-coalesced TCP/UDP packet: request/response
flows, many-flow fan-in, and each run's leftover tail.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
decodeRead failures were silently swallowed; a kernel emitting an
unnegotiated GSO type would blackhole all tun traffic with nothing in
the logs. Debug-gated per the usual idiom so the happy path pays
nothing, which means plumbing the logger down through the offload
queueset.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
gsoTypeFromProto returns GSO_NONE when the IP version nibble is
neither 4 nor 6, so a multi-fragment superpacket went out as one
silent jumbo GSO_NONE packet -- exactly the silent mis-emission the
geometry checks promise not to allow.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ugV2edVqoz3tBvq9J6yWp
35596c7 added the udp-l4-ecn-rejected test but only the ECN mask, so
UDP_L4|ECN validated as plain UDP_L4. Mirror virtio_net_hdr_to_skb and
refuse ECN on anything but TCPV4/TCPV6.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The correctness sweeps only exercised the public Checksum dispatcher, so
wherever it resolved to the gvisor fallback (non-AVX2 amd64, fallback
architectures) the suite compared gvisor against itself and the AVX2
assembly went untested -- silently green. Per-arch export_test.go files
now enumerate the hand-written implementations and every sweep runs
against the dispatcher plus each of them, skipping with an explicit
message when the running CPU can't execute one.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
pseudoSumIPv4/IPv6, foldOnceNoInvert, ipv4HdrChecksum (batch) and
foldComplement (tio/virtio) feed the virtio NEEDS_CSUM contract; a wrong
seed means every coalesced packet is silently dropped by the receiver
with nothing failing on our side. Check them against an independent
reference built from explicit RFC pseudo-header bytes -- deliberately
not the production checksum code -- including the carry/fold edge cases
and an end-to-end seed -> kernel-completion -> receiver-accepts
property.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The length checks were fishy on four counts: an empty hdr/transportHdr
with real payload returned nil (silent drop with a success signal); the
HdrLen/GSOSize/CsumStart uint16 conversions could wrap unchecked;
nothing verified transportHdr covers csum_start+csum_offset, so the
kernel's NEEDS_CSUM write could land in payload bytes; and there was no
total-size bound even though every length field involved is 16-bit.
Malformed geometry is now a real error, and a single 65535 total-length
guard makes all the u16 conversions exact.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
GSOSize came from len(pays[0]) while the iovec build skips empty
fragments, so a leading empty fragment emitted a TSO/USO header with
gso_size == 0 -- virtio_net_hdr_to_skb rejects that with EINVAL and the
whole superpacket is lost. Compute gso_size from the first non-empty
fragment and use the non-empty count to decide superpacket vs plain.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Write took &buf[0] before calling writeWithScratch, so the len==0 guard
in the helper could never run -- a zero-length buffer panicked on the
index instead of returning. Hoist the guard above the indexing and fold
writeWithScratch into Write since it was the only caller and duplicated
the iovec setup.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The Warn("==== end of batch ====") delimiter (and the `logged` flag that
fed it) was left over from debugging the cross-slot gap logging.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
TUN_F_TSO_ECN is negotiated, so once ECN feedback flows the kernel hands
us TSO superpackets typed TCPV4|GSO_ECN (CWR set). protoFromGSOType
treated the qualifier bit as an unknown type and the read path dropped
every such superpacket - a latent bug that only fires when a congested
hop CE-marks the flow, exactly when drops hurt most. The segmenter
already handles CWR (first segment only); just mask the bit.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
JackDoan