Revert "ipn/ipnlocal: remove unnecessary usees of lockAndGetUnlock"

This reverts commit 2fb9472990ea76b30b7ac7c138b856ba9500dfa1.

Reason: rolling back atypical `*Locked` methods.

Updates tailscale/corp#31713

Signed-off-by: Nick Khyl <nickk@tailscale.com>

ipn/ipnlocal/local.go

@@ -797,8 +797,8 @@ func (b *LocalBackend) Dialer() *tsdial.Dialer {
 // It returns (false, nil) if not running in declarative mode, (true, nil) on
 // success, or (false, error) on failure.
 func (b *LocalBackend) ReloadConfig() (ok bool, err error) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	if b.conf == nil {
 		return false, nil
 	}
@@ -1958,8 +1958,8 @@ func (b *LocalBackend) registerSysPolicyWatch() (unregister func(), err error) {
 //
 // b.mu must not be held.
 func (b *LocalBackend) reconcilePrefs() (_ ipn.PrefsView, anyChange bool) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	prefs := b.pm.CurrentPrefs().AsStruct()
 	if !b.reconcilePrefsLocked(prefs) {
 		return prefs.View(), false
@@ -2327,8 +2327,8 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 			clientToShutdown.Shutdown()
 		}
 	}()
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	if opts.UpdatePrefs != nil {
 		if err := b.checkPrefsLocked(opts.UpdatePrefs); err != nil {
@@ -3534,8 +3534,8 @@ func (b *LocalBackend) onClientVersion(v *tailcfg.ClientVersion) {
 }
 
 func (b *LocalBackend) onTailnetDefaultAutoUpdate(au bool) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	prefs := b.pm.CurrentPrefs()
 	if !prefs.Valid() {
@@ -4001,8 +4001,8 @@ func (b *LocalBackend) shouldUploadServices() bool {
 //
 // On non-multi-user systems, the actor should be set to nil.
 func (b *LocalBackend) SetCurrentUser(actor ipnauth.Actor) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	var userIdentifier string
 	if user := cmp.Or(actor, b.currentUser); user != nil {
@@ -4034,8 +4034,8 @@ func (b *LocalBackend) SetCurrentUser(actor ipnauth.Actor) {
 // or disconnecting, or a change in the desktop session state, and is used
 // for logging.
 func (b *LocalBackend) SwitchToBestProfile(reason string) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	b.switchToBestProfileLocked(reason)
 }
 
@@ -4308,8 +4308,8 @@ func (b *LocalBackend) checkAutoUpdatePrefsLocked(p *ipn.Prefs) error {
 // Setting the value to false when use of an exit node is already false is not an error,
 // nor is true when the exit node is already in use.
 func (b *LocalBackend) SetUseExitNodeEnabled(actor ipnauth.Actor, v bool) (ipn.PrefsView, error) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	p0 := b.pm.CurrentPrefs()
 	if v && p0.ExitNodeID() != "" {
@@ -4379,8 +4379,8 @@ func (b *LocalBackend) EditPrefsAs(mp *ipn.MaskedPrefs, actor ipnauth.Actor) (ip
 		return ipn.PrefsView{}, errors.New("can't set Internal fields")
 	}
 
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	return b.editPrefsLocked(actor, mp)
 }
 
@@ -4569,8 +4569,8 @@ func (b *LocalBackend) startReconnectTimerLocked(d time.Duration) {
 	profileID := b.pm.CurrentProfile().ID()
 	var reconnectTimer tstime.TimerController
 	reconnectTimer = b.clock.AfterFunc(d, func() {
-		b.mu.Lock()
-		defer b.mu.Unlock()
+		unlock := b.lockAndGetUnlock()
+		defer unlock()
 
 		if b.reconnectTimer != reconnectTimer {
 			// We're either not the most recent timer, or we lost the race when
@@ -4617,7 +4617,7 @@ func (b *LocalBackend) stopReconnectTimerLocked() {
 	}
 }
 
-// The caller must hold b.mu.
+// Warning: b.mu must be held on entry.
 func (b *LocalBackend) editPrefsLocked(actor ipnauth.Actor, mp *ipn.MaskedPrefs) (ipn.PrefsView, error) {
 	p0 := b.pm.CurrentPrefs()
 
@@ -5664,8 +5664,8 @@ func (b *LocalBackend) applyPrefsToHostinfoLocked(hi *tailcfg.Hostinfo, prefs ip
 // really this is more "one of several places in which random things
 // happen".
 func (b *LocalBackend) enterState(newState ipn.State) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	b.enterStateLocked(newState)
 }
 
@@ -5868,8 +5868,8 @@ func (b *LocalBackend) nextStateLocked() ipn.State {
 // TODO(apenwarr): use a channel or something to prevent reentrancy?
 // Or maybe just call the state machine from fewer places.
 func (b *LocalBackend) stateMachine() {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 	b.stateMachineLocked()
 }
 
@@ -6063,8 +6063,8 @@ func (b *LocalBackend) Logout(ctx context.Context, actor ipnauth.Actor) error {
 	var profile ipn.LoginProfileView
 
 	if err := func() error {
-		b.mu.Lock()
-		defer b.mu.Unlock()
+		unlock := b.lockAndGetUnlock()
+		defer unlock()
 
 		if !b.hasNodeKeyLocked() {
 			// Already logged out.
@@ -6106,8 +6106,8 @@ func (b *LocalBackend) Logout(ctx context.Context, actor ipnauth.Actor) error {
 		return err
 	}
 
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	if err := b.pm.DeleteProfile(profile.ID()); err != nil {
 		b.logf("error deleting profile: %v", err)
@@ -7289,8 +7289,8 @@ func (b *LocalBackend) ShouldInterceptVIPServiceTCPPort(ap netip.AddrPort) bool
 // It will restart the backend on success.
 // If the profile is not known, it returns an errProfileNotFound.
 func (b *LocalBackend) SwitchProfile(profile ipn.ProfileID) error {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	oldControlURL := b.pm.CurrentPrefs().ControlURLOrDefault()
 	if _, changed, err := b.pm.SwitchToProfileByID(profile); !changed || err != nil {
@@ -7384,7 +7384,7 @@ func (b *LocalBackend) getHardwareAddrs() ([]string, error) {
 
 // resetForProfileChangeLocked resets the backend for a profile change.
 //
-// The caller must hold b.mu.
+// b.mu must held on entry. It is released on exit.
 func (b *LocalBackend) resetForProfileChangeLocked() error {
 	if b.shutdownCalled {
 		// Prevent a call back to Start during Shutdown, which calls Logout for
@@ -7434,8 +7434,8 @@ func (b *LocalBackend) resetForProfileChangeLocked() error {
 // DeleteProfile deletes a profile with the given ID.
 // If the profile is not known, it is a no-op.
 func (b *LocalBackend) DeleteProfile(p ipn.ProfileID) error {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	needToRestart := b.pm.CurrentProfile().ID() == p
 	if err := b.pm.DeleteProfile(p); err != nil {
@@ -7460,8 +7460,8 @@ func (b *LocalBackend) CurrentProfile() ipn.LoginProfileView {
 
 // NewProfile creates and switches to the new profile.
 func (b *LocalBackend) NewProfile() error {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	b.pm.SwitchToNewProfile()
 
@@ -7484,8 +7484,8 @@ func (b *LocalBackend) ListProfiles() []ipn.LoginProfileView {
 // backend is left with a new profile, ready for StartLoginInterative to be
 // called to register it as new node.
 func (b *LocalBackend) ResetAuth() error {
-	b.mu.Lock()
-	defer b.mu.Unlock()
+	unlock := b.lockAndGetUnlock()
+	defer unlock()
 
 	prevCC := b.resetControlClientLocked()
 	if prevCC != nil {