In v1.78, we started acquiring the GP lock when reading policy settings. This led to a deadlock during
Tailscale installation via Group Policy Software Installation because the GP engine holds the write lock
for the duration of policy processing, which in turn waits for the installation to complete, which in turn
waits for the service to enter the running state.
In this PR, we prevent the acquisition of GP locks (aka EnterCriticalPolicySection) during service startup
and update the Windows Registry-based util/syspolicy/source.PlatformPolicyStore to handle this failure
gracefully. The GP lock is somewhat optional; it’s safe to read policy settings without it, but acquiring
the lock is recommended when reading multiple values to prevent the Group Policy engine from modifying
settings mid-read and to avoid inconsistent results.
Fixes#14416
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Nick Khyl
f0db47338e