Don't call kernel.Task.Block() from netstack.SocketOperations.Write().

kernel.Task.Block() requires that the caller is running on the task goroutine.
netstack.SocketOperations.Write() uses kernel.TaskFromContext() to call
kernel.Task.Block() even if it's not running on the task goroutine. Stop doing
that.

PiperOrigin-RevId: 311178335

3 files changed, 9 insertions, 22 deletions

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{})
 	}