syncs, all: move to using Go's new atomic types instead of ours

Fixes #5185

Change-Id: I850dd532559af78c3895e2924f8237ccc328449d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/cli.go

@@ -20,6 +20,7 @@
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"text/tabwriter"
 
@@ -29,7 +30,6 @@
 	"tailscale.com/ipn"
 	"tailscale.com/paths"
 	"tailscale.com/safesocket"
-	"tailscale.com/syncs"
 	"tailscale.com/version/distro"
 )
 
@@ -230,7 +230,7 @@ func fatalf(format string, a ...any) {
 	socket string
 }
 
-var gotSignal syncs.AtomicBool
+var gotSignal atomic.Bool
 
 func connect(ctx context.Context) (net.Conn, *ipn.BackendClient, context.Context, context.CancelFunc) {
 	s := safesocket.DefaultConnectionStrategy(rootArgs.socket)

cmd/tailscale/depaware.txt

@@ -71,7 +71,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
      💣 tailscale.com/net/tshttpproxy                                from tailscale.com/derp/derphttp+
         tailscale.com/paths                                          from tailscale.com/cmd/tailscale/cli+
         tailscale.com/safesocket                                     from tailscale.com/cmd/tailscale/cli+
-        tailscale.com/syncs                                          from tailscale.com/net/interfaces+
+        tailscale.com/syncs                                          from tailscale.com/net/netcheck
         tailscale.com/tailcfg                                        from tailscale.com/cmd/tailscale/cli+
         tailscale.com/tka                                            from tailscale.com/types/key
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces

cmd/tailscaled/depaware.txt

@@ -241,7 +241,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/safesocket                                     from tailscale.com/client/tailscale+
         tailscale.com/smallzstd                                      from tailscale.com/ipn/ipnserver+
   LD 💣 tailscale.com/ssh/tailssh                                    from tailscale.com/cmd/tailscaled
-        tailscale.com/syncs                                          from tailscale.com/control/controlknobs+
+        tailscale.com/syncs                                          from tailscale.com/net/netcheck+
         tailscale.com/tailcfg                                        from tailscale.com/client/tailscale/apitype+
   LD    tailscale.com/tempfork/gliderlabs/ssh                        from tailscale.com/ssh/tailssh
         tailscale.com/tka                                            from tailscale.com/types/key+

control/controlknobs/controlknobs.go

@@ -7,12 +7,13 @@
 package controlknobs
 
 import (
+	"sync/atomic"
+
 	"tailscale.com/envknob"
-	"tailscale.com/syncs"
 )
 
 // disableUPnP indicates whether to attempt UPnP mapping.
-var disableUPnP syncs.AtomicBool
+var disableUPnP atomic.Bool
 
 func init() {
 	SetDisableUPnP(envknob.Bool("TS_DISABLE_UPNP"))
@@ -21,11 +22,11 @@ func init() {
 // DisableUPnP reports the last reported value from control
 // whether UPnP portmapping should be disabled.
 func DisableUPnP() bool {
-	return disableUPnP.Get()
+	return disableUPnP.Load()
 }
 
 // SetDisableUPnP sets whether control says that UPnP should be
 // disabled.
 func SetDisableUPnP(v bool) {
-	disableUPnP.Set(v)
+	disableUPnP.Store(v)
 }

derp/derp_server.go

@@ -41,7 +41,6 @@
 	"tailscale.com/disco"
 	"tailscale.com/envknob"
 	"tailscale.com/metrics"
-	"tailscale.com/syncs"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/pad32"
@@ -232,7 +231,7 @@ type dupClientSet struct {
 }
 
 func (s *dupClientSet) ActiveClient() *sclient {
-	if s.last != nil && !s.last.isDisabled.Get() {
+	if s.last != nil && !s.last.isDisabled.Load() {
 		return s.last
 	}
 	return nil
@@ -499,8 +498,8 @@ func (s *Server) registerClient(c *sclient) {
 		s.dupClientConns.Add(2) // both old and new count
 		s.dupClientConnTotal.Add(1)
 		old := set.ActiveClient()
-		old.isDup.Set(true)
+		old.isDup.Store(true)
-		c.isDup.Set(true)
+		c.isDup.Store(true)
 		s.clients[c.key] = &dupClientSet{
 			last: c,
 			set: map[*sclient]bool{
@@ -512,7 +511,7 @@ func (s *Server) registerClient(c *sclient) {
 	case *dupClientSet:
 		s.dupClientConns.Add(1)     // the gauge
 		s.dupClientConnTotal.Add(1) // the counter
-		c.isDup.Set(true)
+		c.isDup.Store(true)
 		set.set[c] = true
 		set.last = c
 		set.sendHistory = append(set.sendHistory, c)
@@ -571,8 +570,8 @@ func (s *Server) unregisterClient(c *sclient) {
 			if remain == nil {
 				panic("unexpected nil remain from single element dup set")
 			}
-			remain.isDisabled.Set(false)
+			remain.isDisabled.Store(false)
-			remain.isDup.Set(false)
+			remain.isDup.Store(false)
 			s.clients[c.key] = singleClient{remain}
 		}
 	}
@@ -1073,11 +1072,11 @@ func (s *Server) sendServerKey(lw *lazyBufioWriter) error {
 }
 
 func (s *Server) noteClientActivity(c *sclient) {
-	if !c.isDup.Get() {
+	if !c.isDup.Load() {
 		// Fast path for clients that aren't in a dup set.
 		return
 	}
-	if c.isDisabled.Get() {
+	if c.isDisabled.Load() {
 		// If they're already disabled, no point checking more.
 		return
 	}
@@ -1112,7 +1111,7 @@ func (s *Server) noteClientActivity(c *sclient) {
 		for _, prior := range ds.sendHistory {
 			if prior == c {
 				ds.ForeachClient(func(c *sclient) {
-					c.isDisabled.Set(true)
+					c.isDisabled.Store(true)
 				})
 				break
 			}
@@ -1253,8 +1252,8 @@ type sclient struct {
 	peerGone       chan key.NodePublic // write request that a previous sender has disconnected (not used by mesh peers)
 	meshUpdate     chan struct{}       // write request to write peerStateChange
 	canMesh        bool                // clientInfo had correct mesh token for inter-region routing
-	isDup          syncs.AtomicBool    // whether more than 1 sclient for key is connected
+	isDup          atomic.Bool         // whether more than 1 sclient for key is connected
-	isDisabled     syncs.AtomicBool    // whether sends to this peer are disabled due to active/active dups
+	isDisabled     atomic.Bool         // whether sends to this peer are disabled due to active/active dups
 
 	// replaceLimiter controls how quickly two connections with
 	// the same client key can kick each other off the server by

ipn/ipnlocal/local.go

@@ -40,7 +40,6 @@
 	"tailscale.com/net/tsdial"
 	"tailscale.com/paths"
 	"tailscale.com/portlist"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tka"
 	"tailscale.com/types/dnstype"
@@ -127,7 +126,7 @@ type LocalBackend struct {
 	serverURL             string           // tailcontrol URL
 	newDecompressor       func() (controlclient.Decompressor, error)
 	varRoot               string // or empty if SetVarRoot never called
-	sshAtomicBool         syncs.AtomicBool
+	sshAtomicBool         atomic.Bool
 	shutdownCalled        bool // if Shutdown has been called
 
 	filterAtomic            atomic.Value // of *filter.Filter
@@ -1740,7 +1739,7 @@ func (b *LocalBackend) loadStateLocked(key ipn.StateKey, prefs *ipn.Prefs) (err
 // setAtomicValuesFromPrefs populates sshAtomicBool and containsViaIPFuncAtomic
 // from the prefs p, which may be nil.
 func (b *LocalBackend) setAtomicValuesFromPrefs(p *ipn.Prefs) {
-	b.sshAtomicBool.Set(p != nil && p.RunSSH && canSSH)
+	b.sshAtomicBool.Store(p != nil && p.RunSSH && canSSH)
 
 	if p == nil {
 		b.containsViaIPFuncAtomic.Store(tsaddr.NewContainsIPFunc(nil))
@@ -3053,7 +3052,7 @@ func (b *LocalBackend) ResetForClientDisconnect() {
 	b.setAtomicValuesFromPrefs(nil)
 }
 
-func (b *LocalBackend) ShouldRunSSH() bool { return b.sshAtomicBool.Get() && canSSH }
+func (b *LocalBackend) ShouldRunSSH() bool { return b.sshAtomicBool.Load() && canSSH }
 
 // ShouldHandleViaIP reports whether whether ip is an IPv6 address in the
 // Tailscale ULA's v6 "via" range embedding an IPv4 address to be forwarded to

ipn/ipnlocal/peerapi.go

@@ -26,6 +26,7 @@
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 	"unicode"
 	"unicode/utf8"
@@ -41,7 +42,6 @@
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netaddr"
 	"tailscale.com/net/netutil"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/wgengine"
@@ -58,7 +58,7 @@ type peerAPIServer struct {
 	b          *LocalBackend
 	rootDir    string // empty means file receiving unavailable
 	selfNode   *tailcfg.Node
-	knownEmpty syncs.AtomicBool
+	knownEmpty atomic.Bool
 	resolver   *resolver.Resolver
 
 	// directFileMode is whether we're writing files directly to a
@@ -144,7 +144,7 @@ func (s *peerAPIServer) hasFilesWaiting() bool {
 	if s == nil || s.rootDir == "" || s.directFileMode {
 		return false
 	}
-	if s.knownEmpty.Get() {
+	if s.knownEmpty.Load() {
 		// Optimization: this is usually empty, so avoid opening
 		// the directory and checking. We can't cache the actual
 		// has-files-or-not values as the macOS/iOS client might
@@ -185,7 +185,7 @@ func (s *peerAPIServer) hasFilesWaiting() bool {
 			}
 		}
 		if err == io.EOF {
-			s.knownEmpty.Set(true)
+			s.knownEmpty.Store(true)
 		}
 		if err != nil {
 			break
@@ -808,7 +808,7 @@ func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
 	// TODO: some real response
 	success = true
 	io.WriteString(w, "{}\n")
-	h.ps.knownEmpty.Set(false)
+	h.ps.knownEmpty.Store(false)
 	h.ps.b.sendFileNotify()
 }
 

ipn/ipnlocal/state_test.go

@@ -7,6 +7,7 @@
 import (
 	"context"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -15,7 +16,6 @@
 	"tailscale.com/control/controlclient"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/store/mem"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
@@ -91,7 +91,7 @@ type mockControl struct {
 	opts       controlclient.Options
 	logfActual logger.Logf
 	statusFunc func(controlclient.Status)
-	preventLog syncs.AtomicBool
+	preventLog atomic.Bool
 
 	mu          sync.Mutex
 	calls       []string
@@ -920,7 +920,7 @@ func TestStateMachine(t *testing.T) {
 
 type testStateStorage struct {
 	mem     mem.Store
-	written syncs.AtomicBool
+	written atomic.Bool
 }
 
 func (s *testStateStorage) ReadState(id ipn.StateKey) ([]byte, error) {

logtail/logtail.go

@@ -23,7 +23,6 @@
 
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/net/interfaces"
-	"tailscale.com/syncs"
 	tslogger "tailscale.com/types/logger"
 	"tailscale.com/wgengine/monitor"
 )
@@ -448,15 +447,15 @@ func (l *Logger) Flush() error {
 }
 
 // logtailDisabled is whether logtail uploads to logcatcher are disabled.
-var logtailDisabled syncs.AtomicBool
+var logtailDisabled atomic.Bool
 
 // Disable disables logtail uploads for the lifetime of the process.
 func Disable() {
-	logtailDisabled.Set(true)
+	logtailDisabled.Store(true)
 }
 
 func (l *Logger) sendLocked(jsonBlob []byte) (int, error) {
-	if logtailDisabled.Get() {
+	if logtailDisabled.Load() {
 		return len(jsonBlob), nil
 	}
 	n, err := l.buffer.Write(jsonBlob)

net/interfaces/interfaces_linux.go

@@ -17,13 +17,13 @@
 	"os/exec"
 	"runtime"
 	"strings"
+	"sync/atomic"
 
 	"github.com/jsimonetti/rtnetlink"
 	"github.com/mdlayher/netlink"
 	"go4.org/mem"
 	"golang.org/x/sys/unix"
 	"tailscale.com/net/netaddr"
-	"tailscale.com/syncs"
 	"tailscale.com/util/lineread"
 )
 
@@ -31,7 +31,7 @@ func init() {
 	likelyHomeRouterIP = likelyHomeRouterIPLinux
 }
 
-var procNetRouteErr syncs.AtomicBool
+var procNetRouteErr atomic.Bool
 
 // errStopReading is a sentinel error value used internally by
 // lineread.File callers to stop reading. It doesn't escape to
@@ -47,7 +47,7 @@ func init() {
 ens18   0000000A        00000000        0001    0       0       0       0000FFFF        0       0       0
 */
 func likelyHomeRouterIPLinux() (ret netip.Addr, ok bool) {
-	if procNetRouteErr.Get() {
+	if procNetRouteErr.Load() {
 		// If we failed to read /proc/net/route previously, don't keep trying.
 		// But if we're on Android, go into the Android path.
 		if runtime.GOOS == "android" {
@@ -93,7 +93,7 @@ func likelyHomeRouterIPLinux() (ret netip.Addr, ok bool) {
 		err = nil
 	}
 	if err != nil {
-		procNetRouteErr.Set(true)
+		procNetRouteErr.Store(true)
 		if runtime.GOOS == "android" {
 			return likelyHomeRouterIPAndroid()
 		}

net/netns/netns.go

@@ -18,25 +18,25 @@
 	"context"
 	"net"
 	"net/netip"
+	"sync/atomic"
 
 	"tailscale.com/net/netknob"
-	"tailscale.com/syncs"
 	"tailscale.com/types/logger"
 )
 
-var disabled syncs.AtomicBool
+var disabled atomic.Bool
 
 // SetEnabled enables or disables netns for the process.
 // It defaults to being enabled.
 func SetEnabled(on bool) {
-	disabled.Set(!on)
+	disabled.Store(!on)
 }
 
 // Listener returns a new net.Listener with its Control hook func
 // initialized as necessary to run in logical network namespace that
 // doesn't route back into Tailscale.
 func Listener(logf logger.Logf) *net.ListenConfig {
-	if disabled.Get() {
+	if disabled.Load() {
 		return new(net.ListenConfig)
 	}
 	return &net.ListenConfig{Control: control(logf)}
@@ -57,7 +57,7 @@ func NewDialer(logf logger.Logf) Dialer {
 // handles using a SOCKS if configured in the environment with
 // ALL_PROXY.
 func FromDialer(logf logger.Logf, d *net.Dialer) Dialer {
-	if disabled.Get() {
+	if disabled.Load() {
 		return d
 	}
 	d.Control = control(logf)

net/portmapper/igd_test.go

@@ -12,10 +12,10 @@
 	"net/http/httptest"
 	"net/netip"
 	"sync"
+	"sync/atomic"
 	"testing"
 
 	"tailscale.com/net/netaddr"
-	"tailscale.com/syncs"
 	"tailscale.com/types/logger"
 )
 
@@ -26,7 +26,7 @@ type TestIGD struct {
 	pxpConn  net.PacketConn // for NAT-PMP and/or PCP
 	ts       *httptest.Server
 	logf     logger.Logf
-	closed   syncs.AtomicBool
+	closed   atomic.Bool
 
 	// do* will log which packets are sent, but will not reply to unexpected packets.
 

portlist/portlist_linux.go

@@ -14,12 +14,12 @@
 	"runtime"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"syscall"
 	"time"
 
 	"go4.org/mem"
 	"golang.org/x/sys/unix"
-	"tailscale.com/syncs"
 )
 
 // Reading the sockfiles on Linux is very fast, so we can do it often.
@@ -27,7 +27,7 @@
 
 var sockfiles = []string{"/proc/net/tcp", "/proc/net/tcp6", "/proc/net/udp", "/proc/net/udp6"}
 
-var sawProcNetPermissionErr syncs.AtomicBool
+var sawProcNetPermissionErr atomic.Bool
 
 const (
 	v6Localhost = "00000000000000000000000001000000:"
@@ -37,7 +37,7 @@
 )
 
 func listPorts() (List, error) {
-	if sawProcNetPermissionErr.Get() {
+	if sawProcNetPermissionErr.Load() {
 		return nil, nil
 	}
 	var ret []Port
@@ -48,13 +48,13 @@ func listPorts() (List, error) {
 		// https://developer.android.com/about/versions/10/privacy/changes#proc-net-filesystem
 		// Ignore it rather than have the system log about our violation.
 		if runtime.GOOS == "android" && syscall.Access(fname, unix.R_OK) != nil {
-			sawProcNetPermissionErr.Set(true)
+			sawProcNetPermissionErr.Store(true)
 			return nil, nil
 		}
 
 		f, err := os.Open(fname)
 		if os.IsPermission(err) {
-			sawProcNetPermissionErr.Set(true)
+			sawProcNetPermissionErr.Store(true)
 			return nil, nil
 		}
 		if err != nil {

prober/prober_test.go

@@ -12,11 +12,11 @@
 	"fmt"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
-	"tailscale.com/syncs"
 	"tailscale.com/tstest"
 	"tailscale.com/tsweb"
 )
@@ -131,7 +131,7 @@ func TestExpvar(t *testing.T) {
 	clk := newFakeTime()
 	p := newForTest(clk.Now, clk.NewTicker)
 
-	var succeed syncs.AtomicBool
+	var succeed atomic.Bool
 	p.Run("probe", probeInterval, map[string]string{"label": "value"}, func(context.Context) error {
 		clk.Advance(aFewMillis)
 		if succeed.Get() {
@@ -189,7 +189,7 @@ func TestPrometheus(t *testing.T) {
 	clk := newFakeTime()
 	p := newForTest(clk.Now, clk.NewTicker)
 
-	var succeed syncs.AtomicBool
+	var succeed atomic.Bool
 	p.Run("testprobe", probeInterval, map[string]string{"label": "value"}, func(context.Context) error {
 		clk.Advance(aFewMillis)
 		if succeed.Get() {

ssh/tailssh/tailssh.go

@@ -30,6 +30,7 @@
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	gossh "github.com/tailscale/golang-x-crypto/ssh"
@@ -37,7 +38,6 @@
 	"tailscale.com/ipn/ipnlocal"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/net/tsaddr"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tempfork/gliderlabs/ssh"
 	"tailscale.com/types/logger"
@@ -645,7 +645,7 @@ func (c *conn) resolveTerminalActionLocked(s ssh.Session, cr *contextReader) (ac
 	action = c.action0
 
 	var awaitReadOnce sync.Once // to start Reads on cr
-	var sawInterrupt syncs.AtomicBool
+	var sawInterrupt atomic.Bool
 	var wg sync.WaitGroup
 	defer wg.Wait() // wait for awaitIntrOnce's goroutine to exit
 
@@ -687,7 +687,7 @@ func (c *conn) resolveTerminalActionLocked(s ssh.Session, cr *contextReader) (ac
 						return
 					}
 					if n > 0 && buf[0] == 0x03 { // Ctrl-C
-						sawInterrupt.Set(true)
+						sawInterrupt.Store(true)
 						s.Stderr().Write([]byte("Canceled.\r\n"))
 						s.Exit(1)
 						return
@@ -699,7 +699,7 @@ func (c *conn) resolveTerminalActionLocked(s ssh.Session, cr *contextReader) (ac
 		var err error
 		action, err = c.fetchSSHAction(ctx, url)
 		if err != nil {
-			if sawInterrupt.Get() {
+			if sawInterrupt.Load() {
 				metricTerminalInterrupt.Add(1)
 				return nil, fmt.Errorf("aborted by user")
 			} else {

syncs/syncs.go

@@ -68,42 +68,6 @@ func (wg *WaitGroupChan) Decr() {
 // Wait blocks until the WaitGroupChan counter is zero.
 func (wg *WaitGroupChan) Wait() { <-wg.done }
 
-// AtomicBool is an atomic boolean.
-type AtomicBool int32
-
-func (b *AtomicBool) Set(v bool) {
-	var n int32
-	if v {
-		n = 1
-	}
-	atomic.StoreInt32((*int32)(b), n)
-}
-
-// Swap sets b to v and reports whether it changed.
-func (b *AtomicBool) Swap(v bool) (changed bool) {
-	var n int32
-	if v {
-		n = 1
-	}
-	old := atomic.SwapInt32((*int32)(b), n)
-	return old != n
-}
-
-func (b *AtomicBool) Get() bool {
-	return atomic.LoadInt32((*int32)(b)) != 0
-}
-
-// AtomicUint32 is an atomic uint32.
-type AtomicUint32 uint32
-
-func (b *AtomicUint32) Set(v uint32) {
-	atomic.StoreUint32((*uint32)(b), v)
-}
-
-func (b *AtomicUint32) Get() uint32 {
-	return atomic.LoadUint32((*uint32)(b))
-}
-
 // Semaphore is a counting semaphore.
 //
 // Use NewSemaphore to create one.

wgengine/magicsock/magicsock.go

@@ -286,20 +286,20 @@ type Conn struct {
 	// is named negatively because in early start-up, we don't yet
 	// necessarily have a netcheck.Report and don't want to skip
 	// logging.
-	noV4, noV6 syncs.AtomicBool
+	noV4, noV6 atomic.Bool
 
 	// noV4Send is whether IPv4 UDP is known to be unable to transmit
 	// at all. This could happen if the socket is in an invalid state
 	// (as can happen on darwin after a network link status change).
-	noV4Send syncs.AtomicBool
+	noV4Send atomic.Bool
 
 	// networkUp is whether the network is up (some interface is up
 	// with IPv4 or IPv6). It's used to suppress log spam and prevent
 	// new connection that'll fail.
-	networkUp syncs.AtomicBool
+	networkUp atomic.Bool
 
 	// havePrivateKey is whether privateKey is non-zero.
-	havePrivateKey  syncs.AtomicBool
+	havePrivateKey  atomic.Bool
 	publicKeyAtomic atomic.Value // of key.NodePublic (or NodeKey zero value if !havePrivateKey)
 
 	// derpMapAtomic is the same as derpMap, but without requiring
@@ -310,7 +310,7 @@ type Conn struct {
 	lastNetCheckReport atomic.Value // of *netcheck.Report
 
 	// port is the preferred port from opts.Port; 0 means auto.
-	port syncs.AtomicUint32
+	port atomic.Uint32
 
 	// ============================================================
 	// mu guards all following fields; see userspaceEngine lock
@@ -531,7 +531,7 @@ func newConn() *Conn {
 	}
 	c.bind = &connBind{Conn: c, closed: true}
 	c.muCond = sync.NewCond(&c.mu)
-	c.networkUp.Set(true) // assume up until told otherwise
+	c.networkUp.Store(true) // assume up until told otherwise
 	return c
 }
 
@@ -542,7 +542,7 @@ func newConn() *Conn {
 // It doesn't start doing anything until Start is called.
 func NewConn(opts Options) (*Conn, error) {
 	c := newConn()
-	c.port.Set(uint32(opts.Port))
+	c.port.Store(uint32(opts.Port))
 	c.logf = opts.logf()
 	c.epFunc = opts.endpointsFunc()
 	c.derpActiveFunc = opts.derpActiveFunc()
@@ -634,7 +634,7 @@ func (c *Conn) updateEndpoints(why string) {
 		c.muCond.Broadcast()
 	}()
 	c.logf("[v1] magicsock: starting endpoint update (%s)", why)
-	if c.noV4Send.Get() && runtime.GOOS != "js" {
+	if c.noV4Send.Load() && runtime.GOOS != "js" {
 		c.mu.Lock()
 		closed := c.closed
 		c.mu.Unlock()
@@ -736,9 +736,9 @@ func (c *Conn) updateNetInfo(ctx context.Context) (*netcheck.Report, error) {
 	}
 
 	c.lastNetCheckReport.Store(report)
-	c.noV4.Set(!report.IPv4)
+	c.noV4.Store(!report.IPv4)
-	c.noV6.Set(!report.IPv6)
+	c.noV6.Store(!report.IPv6)
-	c.noV4Send.Set(!report.IPv4CanSend)
+	c.noV4Send.Store(!report.IPv4CanSend)
 
 	ni := &tailcfg.NetInfo{
 		DERPLatency:           map[string]float64{},
@@ -1074,7 +1074,7 @@ func (c *Conn) determineEndpoints(ctx context.Context) ([]tailcfg.Endpoint, erro
 		// port mapping on their router to the same explicit
 		// port that tailscaled is running with. Worst case
 		// it's an invalid candidate mapping.
-		if port := c.port.Get(); nr.MappingVariesByDestIP.EqualBool(true) && port != 0 {
+		if port := c.port.Load(); nr.MappingVariesByDestIP.EqualBool(true) && port != 0 {
 			if ip, _, err := net.SplitHostPort(nr.GlobalV4); err == nil {
 				addAddr(ipp(net.JoinHostPort(ip, strconv.Itoa(int(port)))), tailcfg.EndpointSTUN4LocalPort)
 			}
@@ -1167,7 +1167,7 @@ func (c *Conn) LocalPort() uint16 {
 
 var errNetworkDown = errors.New("magicsock: network down")
 
-func (c *Conn) networkDown() bool { return !c.networkUp.Get() }
+func (c *Conn) networkDown() bool { return !c.networkUp.Load() }
 
 func (c *Conn) Send(b []byte, ep conn.Endpoint) error {
 	metricSendData.Add(1)
@@ -1207,7 +1207,7 @@ func (c *Conn) sendUDPStd(addr netip.AddrPort, b []byte) (sent bool, err error)
 	switch {
 	case addr.Addr().Is4():
 		_, err = c.pconn4.WriteToUDPAddrPort(b, addr)
-		if err != nil && (c.noV4.Get() || neterror.TreatAsLostUDP(err)) {
+		if err != nil && (c.noV4.Load() || neterror.TreatAsLostUDP(err)) {
 			return false, nil
 		}
 	case addr.Addr().Is6():
@@ -1216,7 +1216,7 @@ func (c *Conn) sendUDPStd(addr netip.AddrPort, b []byte) (sent bool, err error)
 			return false, nil
 		}
 		_, err = c.pconn6.WriteToUDPAddrPort(b, addr)
-		if err != nil && (c.noV6.Get() || neterror.TreatAsLostUDP(err)) {
+		if err != nil && (c.noV6.Load() || neterror.TreatAsLostUDP(err)) {
 			return false, nil
 		}
 	default:
@@ -1674,7 +1674,7 @@ func (c *Conn) receiveIP(b []byte, ipp netip.AddrPort, cache *ippEndpointCache)
 	if c.handleDiscoMessage(b, ipp, key.NodePublic{}) {
 		return nil, false
 	}
-	if !c.havePrivateKey.Get() {
+	if !c.havePrivateKey.Load() {
 		// If we have no private key, we're logged out or
 		// stopped. Don't try to pass these wireguard packets
 		// up to wireguard-go; it'll just complain (issue 1167).
@@ -2140,12 +2140,12 @@ func (c *Conn) discoInfoLocked(k key.DiscoPublic) *discoInfo {
 func (c *Conn) SetNetworkUp(up bool) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	if c.networkUp.Get() == up {
+	if c.networkUp.Load() == up {
 		return
 	}
 
 	c.logf("magicsock: SetNetworkUp(%v)", up)
-	c.networkUp.Set(up)
+	c.networkUp.Store(up)
 
 	if up {
 		c.startDerpHomeConnectLocked()
@@ -2157,10 +2157,10 @@ func (c *Conn) SetNetworkUp(up bool) {
 
 // SetPreferredPort sets the connection's preferred local port.
 func (c *Conn) SetPreferredPort(port uint16) {
-	if uint16(c.port.Get()) == port {
+	if uint16(c.port.Load()) == port {
 		return
 	}
-	c.port.Set(uint32(port))
+	c.port.Store(uint32(port))
 
 	if err := c.rebind(dropCurrentPort); err != nil {
 		c.logf("%w", err)
@@ -2185,7 +2185,7 @@ func (c *Conn) SetPrivateKey(privateKey key.NodePrivate) error {
 		return nil
 	}
 	c.privateKey = newKey
-	c.havePrivateKey.Set(!newKey.IsZero())
+	c.havePrivateKey.Store(!newKey.IsZero())
 
 	if newKey.IsZero() {
 		c.publicKeyAtomic.Store(key.NodePublic{})
@@ -2835,7 +2835,7 @@ func (c *Conn) bindSocket(rucPtr **RebindingUDPConn, network string, curPortFate
 	// Second best is the port that is currently in use.
 	// If those fail, fall back to 0.
 	var ports []uint16
-	if port := uint16(c.port.Get()); port != 0 {
+	if port := uint16(c.port.Load()); port != 0 {
 		ports = append(ports, port)
 	}
 	if ruc.pconn != nil && curPortFate == keepCurrentPort {

wgengine/router/router_linux.go

@@ -14,6 +14,7 @@
 	"os/exec"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -25,7 +26,6 @@
 	"golang.zx2c4.com/wireguard/tun"
 	"tailscale.com/envknob"
 	"tailscale.com/net/tsaddr"
-	"tailscale.com/syncs"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/preftype"
 	"tailscale.com/util/multierr"
@@ -84,7 +84,7 @@ type netfilterRunner interface {
 }
 
 type linuxRouter struct {
-	closed           syncs.AtomicBool
+	closed           atomic.Bool
 	logf             func(fmt string, args ...any)
 	tunname          string
 	linkMon          *monitor.Mon
@@ -97,7 +97,7 @@ type linuxRouter struct {
 
 	// ruleRestorePending is whether a timer has been started to
 	// restore deleted ip rules.
-	ruleRestorePending syncs.AtomicBool
+	ruleRestorePending atomic.Bool
 	ipRuleFixLimiter   *rate.Limiter
 
 	// Various feature checks for the network stack.
@@ -233,7 +233,7 @@ func (r *linuxRouter) onIPRuleDeleted(table uint8, priority uint32) {
 		return
 	}
 	time.AfterFunc(rr.Delay()+250*time.Millisecond, func() {
-		if r.ruleRestorePending.Swap(false) && !r.closed.Get() {
+		if r.ruleRestorePending.Swap(false) && !r.closed.Load() {
 			r.logf("somebody (likely systemd-networkd) deleted ip rules; restoring Tailscale's")
 			r.justAddIPRules()
 		}
@@ -258,7 +258,7 @@ func (r *linuxRouter) Up() error {
 }
 
 func (r *linuxRouter) Close() error {
-	r.closed.Set(true)
+	r.closed.Store(true)
 	if r.unregLinkMon != nil {
 		r.unregLinkMon()
 	}