WIP

Change-Id: Ie985bbc870cb79ce69ed4218c832922fcecca5c9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

net/dns/manager_linux.go

@@ -40,7 +40,7 @@ var publishOnce sync.Once
 // This is particularly useful because certain conditions can cause indefinite hangs
 // (such as improper dbus auth followed by contextless dbus.Object.Call).
 // Such operations should be wrapped in a timeout context.
-const reconfigTimeout = time.Second
+const reconfigTimeout = 5 * time.Second
 
 // Set unless ts_omit_networkmanager
 var (

net/dns/manager_linux_test.go

@@ -6,14 +6,27 @@ package dns
 import (
 	"errors"
 	"io/fs"
+	"net/netip"
 	"os"
 	"strings"
 	"testing"
 
 	"tailscale.com/tstest"
 	"tailscale.com/util/cmpver"
+	"tailscale.com/util/must"
 )
 
+func TestBradNetworkManager(t *testing.T) {
+	m := must.Get(newNMManager("wlp3s0"))
+	must.Do(m.SetDNS(OSConfig{
+		Nameservers: []netip.Addr{
+			netip.MustParseAddr("10.0.0.2"),
+			netip.MustParseAddr("10.0.0.3"),
+		},
+	}))
+	t.Logf("done")
+}
+
 func TestLinuxDNSMode(t *testing.T) {
 	tests := []struct {
 		name    string

util/eventbus/subscribe.go

@@ -245,6 +245,9 @@ func (s *Subscriber[T]) dispatch(ctx context.Context, vals *queue[DeliveredEvent
 		case <-s.slow.C:
 			s.logf("subscriber for %T is slow (%v elapsed)", t, time.Since(start))
 			s.slow.Reset(slowSubscriberTimeout)
+			all := make([]byte, 2<<20)
+			n := runtime.Stack(all, true)
+			panic("TOO SLOW: " + string(all[:n]))
 		}
 	}
 }
@@ -344,6 +347,9 @@ func (s *SubscriberFunc[T]) dispatch(ctx context.Context, vals *queue[DeliveredE
 		case <-s.slow.C:
 			s.logf("subscriber for %T is slow (%v elapsed)", t, time.Since(start))
 			s.slow.Reset(slowSubscriberTimeout)
+			all := make([]byte, 2<<20)
+			n := runtime.Stack(all, true)
+			panic("TOO SLOW: " + string(all[:n]))
 		}
 	}
 }