1 files changed, 0 insertions, 176 deletions
diff --git a/pkg/flipcall/ctrl_futex.go b/pkg/flipcall/ctrl_futex.go
deleted file mode 100644
index 8390915a2..000000000
--- a/pkg/flipcall/ctrl_futex.go
+++ /dev/null
@@ -1,176 +0,0 @@
-// Copyright 2019 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package flipcall
-
-import (
-	"encoding/json"
-	"fmt"
-	"math"
-	"sync/atomic"
-
-	"gvisor.dev/gvisor/pkg/log"
-)
-
-type endpointControlImpl struct {
-	state int32
-}
-
-// Bits in endpointControlImpl.state.
-const (
-	epsBlocked = 1 << iota
-	epsShutdown
-)
-
-func (ep *Endpoint) ctrlInit(opts ...EndpointOption) error {
-	if len(opts) != 0 {
-		return fmt.Errorf("unknown EndpointOption: %T", opts[0])
-	}
-	return nil
-}
-
-type ctrlHandshakeRequest struct{}
-
-type ctrlHandshakeResponse struct{}
-
-func (ep *Endpoint) ctrlConnect() error {
-	if err := ep.enterFutexWait(); err != nil {
-		return err
-	}
-	_, err := ep.futexConnect(&ctrlHandshakeRequest{})
-	ep.exitFutexWait()
-	return err
-}
-
-func (ep *Endpoint) ctrlWaitFirst() error {
-	if err := ep.enterFutexWait(); err != nil {
-		return err
-	}
-	defer ep.exitFutexWait()
-
-	// Wait for the handshake request.
-	if err := ep.futexSwitchFromPeer(); err != nil {
-		return err
-	}
-
-	// Read the handshake request.
-	reqLen := atomic.LoadUint32(ep.dataLen())
-	if reqLen > ep.dataCap {
-		return fmt.Errorf("invalid handshake request length %d (maximum %d)", reqLen, ep.dataCap)
-	}
-	var req ctrlHandshakeRequest
-	if err := json.NewDecoder(ep.NewReader(reqLen)).Decode(&req); err != nil {
-		return fmt.Errorf("error reading handshake request: %v", err)
-	}
-
-	// Write the handshake response.
-	w := ep.NewWriter()
-	if err := json.NewEncoder(w).Encode(ctrlHandshakeResponse{}); err != nil {
-		return fmt.Errorf("error writing handshake response: %v", err)
-	}
-	*ep.dataLen() = w.Len()
-
-	// Return control to the client.
-	raceBecomeInactive()
-	if err := ep.futexSwitchToPeer(); err != nil {
-		return err
-	}
-
-	// Wait for the first non-handshake message.
-	return ep.futexSwitchFromPeer()
-}
-
-func (ep *Endpoint) ctrlRoundTrip() error {
-	if err := ep.futexSwitchToPeer(); err != nil {
-		return err
-	}
-	if err := ep.enterFutexWait(); err != nil {
-		return err
-	}
-	err := ep.futexSwitchFromPeer()
-	ep.exitFutexWait()
-	return err
-}
-
-func (ep *Endpoint) ctrlWakeLast() error {
-	return ep.futexSwitchToPeer()
-}
-
-func (ep *Endpoint) enterFutexWait() error {
-	switch eps := atomic.AddInt32(&ep.ctrl.state, epsBlocked); eps {
-	case epsBlocked:
-		return nil
-	case epsBlocked | epsShutdown:
-		atomic.AddInt32(&ep.ctrl.state, -epsBlocked)
-		return shutdownError{}
-	default:
-		// Most likely due to ep.enterFutexWait() being called concurrently
-		// from multiple goroutines.
-		panic(fmt.Sprintf("invalid flipcall.Endpoint.ctrl.state before flipcall.Endpoint.enterFutexWait(): %v", eps-epsBlocked))
-	}
-}
-
-func (ep *Endpoint) exitFutexWait() {
-	switch eps := atomic.AddInt32(&ep.ctrl.state, -epsBlocked); eps {
-	case 0:
-		return
-	case epsShutdown:
-		// ep.ctrlShutdown() was called while we were blocked, so we are
-		// repsonsible for indicating connection shutdown.
-		ep.shutdownConn()
-	default:
-		panic(fmt.Sprintf("invalid flipcall.Endpoint.ctrl.state after flipcall.Endpoint.exitFutexWait(): %v", eps+epsBlocked))
-	}
-}
-
-func (ep *Endpoint) ctrlShutdown() {
-	// Set epsShutdown to ensure that future calls to ep.enterFutexWait() fail.
-	if atomic.AddInt32(&ep.ctrl.state, epsShutdown)&epsBlocked != 0 {
-		// Wake the blocked thread. This must loop because it's possible that
-		// FUTEX_WAKE occurs after the waiter sets epsBlocked, but before it
-		// blocks in FUTEX_WAIT.
-		for {
-			// Wake MaxInt32 threads to prevent a broken or malicious peer from
-			// swallowing our wakeup by FUTEX_WAITing from multiple threads.
-			if err := ep.futexWakeConnState(math.MaxInt32); err != nil {
-				log.Warningf("failed to FUTEX_WAKE Endpoints: %v", err)
-				break
-			}
-			yieldThread()
-			if atomic.LoadInt32(&ep.ctrl.state)&epsBlocked == 0 {
-				break
-			}
-		}
-	} else {
-		// There is no blocked thread, so we are responsible for indicating
-		// connection shutdown.
-		ep.shutdownConn()
-	}
-}
-
-func (ep *Endpoint) shutdownConn() {
-	switch cs := atomic.SwapUint32(ep.connState(), csShutdown); cs {
-	case ep.activeState:
-		if err := ep.futexWakeConnState(1); err != nil {
-			log.Warningf("failed to FUTEX_WAKE peer Endpoint for shutdown: %v", err)
-		}
-	case ep.inactiveState:
-		// The peer is currently active and will detect shutdown when it tries
-		// to update the connection state.
-	case csShutdown:
-		// The peer also called Endpoint.Shutdown().
-	default:
-		log.Warningf("unexpected connection state before Endpoint.shutdownConn(): %v", cs)
-	}
-}