syncs: start working on mutex debugging, registrationbradfitz/mutex_debug

Updates #17852

Change-Id: Ib1b634eedd30cc4006bc1b39aa8d479d37c5f1f2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

4 files changed, 8 insertions, 3 deletions

diff --git a/control/controlbase/conn.go b/control/controlbase/conn.go
index 78ef73f71..8a3a90495 100644
--- a/control/controlbase/conn.go
+++ b/control/controlbase/conn.go
@@ -61,7 +61,7 @@ type rxState struct {
 
 // txState is all the Conn state that Write uses.
 type txState struct {
-	sync.Mutex
+	syncs.Mutex
 	cipher cipher.AEAD
 	nonce  nonce
 	err    error // records the first partial write error for all future calls
diff --git a/control/controlbase/handshake.go b/control/controlbase/handshake.go
index 765a4620b..a57a3eca3 100644
--- a/control/controlbase/handshake.go
+++ b/control/controlbase/handshake.go
@@ -20,6 +20,7 @@ import (
 	chp "golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/crypto/curve25519"
 	"golang.org/x/crypto/hkdf"
+	"tailscale.com/syncs"
 	"tailscale.com/types/key"
 )
 
@@ -186,6 +187,8 @@ func continueClientHandshake(ctx context.Context, conn net.Conn, s *symmetricSta
 			cipher: c2,
 		},
 	}
+	syncs.RegisterMutex(&c.rx.Mutex, "controlbase.Conn.rx.Mutex")
+	syncs.RegisterMutex(&c.tx.Mutex, "controlbase.Conn.tx.Mutex")
 	return c, nil
 }
 
diff --git a/control/controlclient/auto.go b/control/controlclient/auto.go
index 336a8d491..235c5e03d 100644
--- a/control/controlclient/auto.go
+++ b/control/controlclient/auto.go
@@ -8,11 +8,11 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
-	"sync"
 	"sync/atomic"
 	"time"
 
 	"tailscale.com/net/sockstats"
+	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tstime"
 	"tailscale.com/types/key"
@@ -122,7 +122,7 @@ type Auto struct {
 	observerQueue execqueue.ExecQueue
 	shutdownFn    func() // to be called prior to shutdown or nil
 
-	mu sync.Mutex // mutex guards the following fields
+	mu syncs.Mutex // mutex guards the following fields
 
 	started      bool   // whether [Auto.Start] has been called
 	wantLoggedIn bool   // whether the user wants to be logged in per last method call
@@ -194,6 +194,7 @@ func newNoStart(opts Options) (_ *Auto, err error) {
 		observer:   opts.Observer,
 		shutdownFn: opts.Shutdown,
 	}
+	syncs.RegisterMutex(&c.mu, "controlclient.Auto.mu")
 
 	c.authCtx, c.authCancel = context.WithCancel(context.Background())
 	c.authCtx = sockstats.WithSockStats(c.authCtx, sockstats.LabelControlClientAuto, opts.Logf)
diff --git a/control/controlclient/direct.go b/control/controlclient/direct.go
index d5cd6a13e..9680da0be 100644
--- a/control/controlclient/direct.go
+++ b/control/controlclient/direct.go
@@ -328,6 +328,7 @@ func NewDirect(opts Options) (*Direct, error) {
 		dnsCache:              dnsCache,
 		dialPlan:              opts.DialPlan,
 	}
+	syncs.RegisterMutex(&c.mu, "controlclient.Direct.mu")
 	c.discoPubKey = opts.DiscoPublicKey
 	c.closedCtx, c.closeCtx = context.WithCancel(context.Background())