Merge release-20211019.0-48-g8acc3a9bb (automated)

2 files changed, 25 insertions, 8 deletions

diff --git a/pkg/tcpip/link/sharedmem/queue/rx.go b/pkg/tcpip/link/sharedmem/queue/rx.go
index a78826ebc..89bdf5ef6 100644
--- a/pkg/tcpip/link/sharedmem/queue/rx.go
+++ b/pkg/tcpip/link/sharedmem/queue/rx.go
@@ -49,9 +49,16 @@ const (
 	sizeOfConsumedBuffer = 28
 
 	// The following are the allowed states of the shared data area.
-	eventFDUninitialized = 0
-	eventFDDisabled      = 1
-	eventFDEnabled       = 2
+	// EventFDUinitialized is the value stored at the start of the shared data
+	// region when it hasn't been initialized.
+	EventFDUninitialized = 0
+	// EventFDDisabled is the value stored at the start of the shared data region
+	// when notifications using eventFD has been disabled.
+	EventFDDisabled = 1
+	// EventFDEnabled is the value stored at the start of the shared data region
+	// when eventFD should be notified as the peer might be blocked waiting on
+	// notifications.
+	EventFDEnabled = 2
 )
 
 // RxBuffer is the descriptor of a receive buffer.
@@ -84,13 +91,13 @@ func (r *Rx) Init(tx, rx []byte, sharedEventFDState *uint32) {
 // EnableNotification updates the shared state such that the peer will notify
 // the eventfd when there are packets to be dequeued.
 func (r *Rx) EnableNotification() {
-	atomic.StoreUint32(r.sharedEventFDState, eventFDEnabled)
+	atomic.StoreUint32(r.sharedEventFDState, EventFDEnabled)
 }
 
 // DisableNotification updates the shared state such that the peer will not
 // notify the eventfd.
 func (r *Rx) DisableNotification() {
-	atomic.StoreUint32(r.sharedEventFDState, eventFDDisabled)
+	atomic.StoreUint32(r.sharedEventFDState, EventFDDisabled)
 }
 
 // PostedBuffersLimit returns the maximum number of buffers that can be posted
diff --git a/pkg/tcpip/link/sharedmem/queue/tx.go b/pkg/tcpip/link/sharedmem/queue/tx.go
index beffe807b..09907c761 100644
--- a/pkg/tcpip/link/sharedmem/queue/tx.go
+++ b/pkg/tcpip/link/sharedmem/queue/tx.go
@@ -16,6 +16,7 @@ package queue
 
 import (
 	"encoding/binary"
+	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/tcpip/link/sharedmem/pipe"
@@ -49,14 +50,23 @@ type TxBuffer struct {
 //
 // This struct is thread-compatible.
 type Tx struct {
-	tx pipe.Tx
-	rx pipe.Rx
+	tx                 pipe.Tx
+	rx                 pipe.Rx
+	sharedEventFDState *uint32
 }
 
 // Init initializes the transmit queue with the given pipes.
-func (t *Tx) Init(tx, rx []byte) {
+func (t *Tx) Init(tx, rx []byte, sharedEventFDState *uint32) {
 	t.tx.Init(tx)
 	t.rx.Init(rx)
+	t.sharedEventFDState = sharedEventFDState
+}
+
+// NotificationsEnabled returns true if eventFD should be used to notify the
+// peer of events (eg. packet transmit etc).
+func (t *Tx) NotificationsEnabled() bool {
+	// Notifications are considered enabled unless explicitly disabled.
+	return atomic.LoadUint32(t.sharedEventFDState) != EventFDDisabled
 }
 
 // Enqueue queues the given linked list of buffers for transmission as one