Running corp/ipn#TestNetworkLockE2E has a 1/300 chance of failing, and
deskchecking suggests thats whats happening are two netmaps are racing each
other to be processed through tkaSyncIfNeededLocked. This happens in the
first place because we release b.mu during network RPCs.
To fix this, we make the tka sync logic an exclusive section, so two
netmaps will need to wait for tka sync to complete serially (which is what
we would want anyway, as the second run through probably wont need to
sync).
Signed-off-by: Tom DNetto <tom@tailscale.com>
* tka.State.staticValidateCheckpoint could call methods on a contained key prior to calling StaticValidate on that key
* Remove broken backoff / RPC retry logic from tka methods in ipn/ipnlocal, to be fixed at a later time
* Fix NetworkLockModify() which would attempt to take b.mu twice and deadlock, remove now-unused dependence on netmap
* Add methods on ipnlocal.LocalBackend to be used in integration tests
* Use TAILSCALE_USE_WIP_CODE as the feature flag so it can be manipulated in tests
Signed-off-by: Tom DNetto <tom@tailscale.com>
