From 4369db522b3fd7adc28a2a82b89315a6f3edbcc4 Mon Sep 17 00:00:00 2001 From: Dmytro Shynkevych Date: Wed, 24 Jun 2020 01:35:41 -0400 Subject: [PATCH] device: wait for routines to stop before removing peers Peers are currently removed after Device's goroutines are signaled to stop, but without waiting for them to actually do so, which is racy. For example, RoutineHandshake may be in Peer.SendKeepalive when the corresponding peer is removed, which closes its nonce channel. This causes a send on a closed channel, as observed in tailscale/tailscale#487. This patch seems to be the correct synchronizing action: Peer's goroutines are receivers and handle channel closure gracefully, so Device's goroutines are the ones that should be fully stopped first. Signed-Off-By: Dmytro Shynkevych --- device/device.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/device/device.go b/device/device.go index c64432e..c440679 100644 --- a/device/device.go +++ b/device/device.go @@ -383,10 +383,10 @@ func (device *Device) Close() { device.isUp.Set(false) close(device.signals.stop) + device.state.stopping.Wait() device.RemoveAllPeers() - device.state.stopping.Wait() device.FlushPacketQueues() device.rate.limiter.Close()