Make link queue writes nonblocking: gVisor can generate replies on the
reader needed to drain the queue. A full queue drops only the rejected
packet and reports ErrNoBufferSpace, which gVisor counts and TCP handles
by arming its retransmit timer. UDP sockets do not see the error unless
IP_RECVERR is set, matching Linux. Count WireGuard-bound drops as
reason="queue_full" in tailscaled_outbound_dropped_packets_total, and
per-queue drops in debug and client metrics.
Add Wrapper.TryInjectOutbound for best-effort replies generated while
processing packets (TSMP rejects and pongs, conn25 rejects, fake-mode
echo replies), so those paths drop instead of stalling behind the
injection queue's reader. Its drops are also counted as queue_full.
Make outbound injection waits cancellable and close link queues before
abort-generated replies. Stop the WireGuard injection pump on ErrClosed.
Release injected packets still queued at Close, outside closeOnce to
allow reentrant release callbacks; a sender whose send races with Close
releases the packet itself. Release temporary capture buffers.
Copy injected payload views directly into the WireGuard slab, avoiding
an intermediate allocation and copy.
Test queue saturation, multiqueue progress, cancellation, concurrent
shutdown, reference ownership, fragmented payloads, and GSO.
Performance versus the parent commit, on a 4-core Xeon 6975P-C:
inject+read 64B / 1280B 245ns / 479ns -> 187ns / 195ns, 0 allocs
4 injectors, 1 reader 843ns -> 451ns
64KiB GSO inject+split 10.9us -> 4.4us, 64KiB/op -> 0
link queue write+read 81.4ns -> 81.5ns
tsnet TCP, 1 / 8 streams 448 / 580 MB/s -> 492 / 674 MB/s
BenchmarkTCPQueueBottleneck shows that dropping on full queues keeps
throughput at the bottleneck rate (117 MB/s at 100k packets/s, as with
blocking writes), at the cost of more retransmits with many streams.
Fixes#21631
Updates #21638
Updates #21632
Updates #21639
Signed-off-by: James Tucker <james@tailscale.com>
Engine.PeerForIP was pure delegation to the callback that LocalBackend
installs via SetPeerForIPFunc, so external callers going through the
engine were taking a pointless round trip: LocalBackend called
b.e.PeerForIP, which called right back into LocalBackend, and the
netstack UseNetstackForIP hooks in tsnet and tailscaled did the same
dance one layer removed.
Export LocalBackend.PeerForIP and make those callers use it directly.
The engine-internal cold paths (Ping, TSMP disco advertisements,
pendopen diagnostics) still need the lookup and have no netmap of
their own, so SetPeerForIPFunc stays on the interface, but the lookup
method itself is now unexported and gone from the Engine interface.
In tailscaled the UseNetstackForIP hook moves from netstack setup to
just after the LocalBackend is created, since the backend doesn't
exist yet when netstack is wired up.
Updates #12542
Change-Id: Ib1e1a4fa5c84ee0dcb9ce5d1910047f2bab9453c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This file was never truly necessary and has never actually been used in
the history of Tailscale's open source releases.
A Brief History of AUTHORS files
---
The AUTHORS file was a pattern developed at Google, originally for
Chromium, then adopted by Go and a bunch of other projects. The problem
was that Chromium originally had a copyright line only recognizing
Google as the copyright holder. Because Google (and most open source
projects) do not require copyright assignemnt for contributions, each
contributor maintains their copyright. Some large corporate contributors
then tried to add their own name to the copyright line in the LICENSE
file or in file headers. This quickly becomes unwieldy, and puts a
tremendous burden on anyone building on top of Chromium, since the
license requires that they keep all copyright lines intact.
The compromise was to create an AUTHORS file that would list all of the
copyright holders. The LICENSE file and source file headers would then
include that list by reference, listing the copyright holder as "The
Chromium Authors".
This also become cumbersome to simply keep the file up to date with a
high rate of new contributors. Plus it's not always obvious who the
copyright holder is. Sometimes it is the individual making the
contribution, but many times it may be their employer. There is no way
for the proejct maintainer to know.
Eventually, Google changed their policy to no longer recommend trying to
keep the AUTHORS file up to date proactively, and instead to only add to
it when requested: https://opensource.google/docs/releasing/authors.
They are also clear that:
> Adding contributors to the AUTHORS file is entirely within the
> project's discretion and has no implications for copyright ownership.
It was primarily added to appease a small number of large contributors
that insisted that they be recognized as copyright holders (which was
entirely their right to do). But it's not truly necessary, and not even
the most accurate way of identifying contributors and/or copyright
holders.
In practice, we've never added anyone to our AUTHORS file. It only lists
Tailscale, so it's not really serving any purpose. It also causes
confusion because Tailscalars put the "Tailscale Inc & AUTHORS" header
in other open source repos which don't actually have an AUTHORS file, so
it's ambiguous what that means.
Instead, we just acknowledge that the contributors to Tailscale (whoever
they are) are copyright holders for their individual contributions. We
also have the benefit of using the DCO (developercertificate.org) which
provides some additional certification of their right to make the
contribution.
The source file changes were purely mechanical with:
git ls-files | xargs sed -i -e 's/\(Tailscale Inc &\) AUTHORS/\1 contributors/g'
Updates #cleanup
Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d
Signed-off-by: Will Norris <will@tailscale.com>
Baby steps. This permits building without much of gvisor, but not all of it.
Updates #17283
Change-Id: I8433146e259918cc901fe86b4ea29be22075b32c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
James Tucker