5 files changed, 27 insertions, 22 deletions
diff --git a/pkg/amutex/BUILD b/pkg/amutex/BUILD
index 9612f072e..ffc918846 100644
--- a/pkg/amutex/BUILD
+++ b/pkg/amutex/BUILD
@@ -6,6 +6,7 @@ go_library(
     name = "amutex",
     srcs = ["amutex.go"],
     visibility = ["//:sandbox"],
+    deps = ["//pkg/syserror"],
 )
 
 go_test(
diff --git a/pkg/amutex/amutex.go b/pkg/amutex/amutex.go
index 1c4fd1784..a078a31db 100644
--- a/pkg/amutex/amutex.go
+++ b/pkg/amutex/amutex.go
@@ -18,6 +18,8 @@ package amutex
 
 import (
 	"sync/atomic"
+
+	"gvisor.dev/gvisor/pkg/syserror"
 )
 
 // Sleeper must be implemented by users of the abortable mutex to allow for
@@ -53,6 +55,21 @@ func (NoopSleeper) SleepFinish(success bool) {}
 // Interrupted implements Sleeper.Interrupted.
 func (NoopSleeper) Interrupted() bool { return false }
 
+// Block blocks until either receiving from ch succeeds (in which case it
+// returns nil) or sleeper is interrupted (in which case it returns
+// syserror.ErrInterrupted).
+func Block(sleeper Sleeper, ch <-chan struct{}) error {
+	cancel := sleeper.SleepStart()
+	select {
+	case <-ch:
+		sleeper.SleepFinish(true)
+		return nil
+	case <-cancel:
+		sleeper.SleepFinish(false)
+		return syserror.ErrInterrupted
+	}
+}
+
 // AbortableMutex is an abortable mutex. It allows Lock() to be aborted while it
 // waits to acquire the mutex.
 type AbortableMutex struct {
diff --git a/pkg/sentry/socket/netstack/BUILD b/pkg/sentry/socket/netstack/BUILD
index 6129fb83d..333e0042e 100644
--- a/pkg/sentry/socket/netstack/BUILD
+++ b/pkg/sentry/socket/netstack/BUILD
@@ -18,6 +18,7 @@ go_library(
     ],
     deps = [
         "//pkg/abi/linux",
+        "//pkg/amutex",
         "//pkg/binary",
         "//pkg/context",
         "//pkg/log",
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 81053d8ef..9d032f052 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -34,6 +34,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/amutex"
 	"gvisor.dev/gvisor/pkg/binary"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
@@ -553,11 +554,9 @@ func (s *SocketOperations) Write(ctx context.Context, _ *fs.File, src usermem.IO
 	}
 
 	if resCh != nil {
-		t := kernel.TaskFromContext(ctx)
-		if err := t.Block(resCh); err != nil {
-			return 0, syserr.FromError(err).ToError()
+		if err := amutex.Block(ctx, resCh); err != nil {
+			return 0, err
 		}
-
 		n, _, err = s.Endpoint.Write(f, tcpip.WriteOptions{})
 	}
 
@@ -626,11 +625,9 @@ func (s *SocketOperations) ReadFrom(ctx context.Context, _ *fs.File, r io.Reader
 	}
 
 	if resCh != nil {
-		t := kernel.TaskFromContext(ctx)
-		if err := t.Block(resCh); err != nil {
-			return 0, syserr.FromError(err).ToError()
+		if err := amutex.Block(ctx, resCh); err != nil {
+			return 0, err
 		}
-
 		n, _, err = s.Endpoint.Write(f, tcpip.WriteOptions{
 			Atomic: true, // See above.
 		})
diff --git a/pkg/sentry/socket/netstack/netstack_vfs2.go b/pkg/sentry/socket/netstack/netstack_vfs2.go
index 191970d41..fcd8013c0 100644
--- a/pkg/sentry/socket/netstack/netstack_vfs2.go
+++ b/pkg/sentry/socket/netstack/netstack_vfs2.go
@@ -16,6 +16,7 @@ package netstack
 
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/amutex"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/sockfs"
@@ -89,11 +90,6 @@ func (s *SocketVFS2) EventUnregister(e *waiter.Entry) {
 	s.socketOpsCommon.EventUnregister(e)
 }
 
-// PRead implements vfs.FileDescriptionImpl.
-func (s *SocketVFS2) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
-	return 0, syserror.ESPIPE
-}
-
 // Read implements vfs.FileDescriptionImpl.
 func (s *SocketVFS2) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
 	// All flags other than RWF_NOWAIT should be ignored.
@@ -115,11 +111,6 @@ func (s *SocketVFS2) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.
 	return int64(n), nil
 }
 
-// PWrite implements vfs.FileDescriptionImpl.
-func (s *SocketVFS2) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
-	return 0, syserror.ESPIPE
-}
-
 // Write implements vfs.FileDescriptionImpl.
 func (s *SocketVFS2) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
 	// All flags other than RWF_NOWAIT should be ignored.
@@ -135,11 +126,9 @@ func (s *SocketVFS2) Write(ctx context.Context, src usermem.IOSequence, opts vfs
 	}
 
 	if resCh != nil {
-		t := kernel.TaskFromContext(ctx)
-		if err := t.Block(resCh); err != nil {
-			return 0, syserr.FromError(err).ToError()
+		if err := amutex.Block(ctx, resCh); err != nil {
+			return 0, err
 		}
-
 		n, _, err = s.Endpoint.Write(f, tcpip.WriteOptions{})
 	}