From 9a7078985338c4699228373b16d93d3227b3723e Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Tue, 2 Feb 2021 14:48:39 -0800
Subject: [PATCH] cmd/tailscale: fix IPN message reading stall in tailscale
 status -web

Fixes #1234
Updates #1254
---
 cmd/tailscale/cli/status.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/cmd/tailscale/cli/status.go b/cmd/tailscale/cli/status.go
index 022eb1328..f4f8c78ad 100644
--- a/cmd/tailscale/cli/status.go
+++ b/cmd/tailscale/cli/status.go
@@ -65,7 +65,17 @@ func runStatus(ctx context.Context, args []string) error {
 			log.Fatal(*n.ErrMessage)
 		}
 		if n.Status != nil {
-			ch <- n.Status
+			select {
+			case ch <- n.Status:
+			default:
+				// A status update from somebody else's request.
+				// Ignoring this matters mostly for "tailscale status -web"
+				// mode, otherwise the channel send would block forever
+				// and pump would stop reading from tailscaled, which
+				// previously caused tailscaled to block (while holding
+				// a mutex), backing up unrelated clients.
+				// See https://github.com/tailscale/tailscale/issues/1234
+			}
 		}
 	})
 	go pump(ctx, bc, c)