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>

net/interfaces/interfaces_linux.go

@@ -17,13 +17,13 @@ import (
 	"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 @@ ens18   00000000        0100000A        0003    0       0       0       00000000
 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 @@ import (
 	"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 @@ import (
 	"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.
 
@@ -71,7 +71,7 @@ func NewTestIGD(logf logger.Logf, t TestIGDOptions) (*TestIGD, error) {
 	d.logf = func(msg string, args ...any) {
 		// Don't log after the device has closed;
 		// stray trailing logging angers testing.T.Logf.
-		if d.closed.Get() {
+		if d.closed.Load() {
 			return
 		}
 		logf(msg, args...)
@@ -107,7 +107,7 @@ func testIPAndGateway() (gw, ip netip.Addr, ok bool) {
 }
 
 func (d *TestIGD) Close() error {
-	d.closed.Set(true)
+	d.closed.Store(true)
 	d.ts.Close()
 	d.upnpConn.Close()
 	d.pxpConn.Close()
@@ -135,7 +135,7 @@ func (d *TestIGD) serveUPnPDiscovery() {
 	for {
 		n, src, err := d.upnpConn.ReadFrom(buf)
 		if err != nil {
-			if !d.closed.Get() {
+			if !d.closed.Load() {
 				d.logf("serveUPnP failed: %v", err)
 			}
 			return
@@ -162,7 +162,7 @@ func (d *TestIGD) servePxP() {
 	for {
 		n, a, err := d.pxpConn.ReadFrom(buf)
 		if err != nil {
-			if !d.closed.Get() {
+			if !d.closed.Load() {
 				d.logf("servePxP failed: %v", err)
 			}
 			return