diff --git a/vendor/google.golang.org/grpc/internal/transport/controlbuf.go b/vendor/google.golang.org/grpc/internal/transport/controlbuf.go
index 204ba15..ddee20b 100644
--- a/vendor/google.golang.org/grpc/internal/transport/controlbuf.go
+++ b/vendor/google.golang.org/grpc/internal/transport/controlbuf.go
@@ -23,6 +23,7 @@
 	"fmt"
 	"runtime"
 	"sync"
+	"sync/atomic"
 
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/hpack"
@@ -84,24 +85,40 @@
 // the control buffer of transport. They represent different aspects of
 // control tasks, e.g., flow control, settings, streaming resetting, etc.
 
+// maxQueuedTransportResponseFrames is the most queued "transport response"
+// frames we will buffer before preventing new reads from occurring on the
+// transport.  These are control frames sent in response to client requests,
+// such as RST_STREAM due to bad headers or settings acks.
+const maxQueuedTransportResponseFrames = 50
+
+type cbItem interface {
+	isTransportResponseFrame() bool
+}
+
 // registerStream is used to register an incoming stream with loopy writer.
 type registerStream struct {
 	streamID uint32
 	wq       *writeQuota
 }
 
+func (*registerStream) isTransportResponseFrame() bool { return false }
+
 // headerFrame is also used to register stream on the client-side.
 type headerFrame struct {
 	streamID   uint32
 	hf         []hpack.HeaderField
-	endStream  bool                       // Valid on server side.
-	initStream func(uint32) (bool, error) // Used only on the client side.
+	endStream  bool               // Valid on server side.
+	initStream func(uint32) error // Used only on the client side.
 	onWrite    func()
 	wq         *writeQuota    // write quota for the stream created.
 	cleanup    *cleanupStream // Valid on the server side.
 	onOrphaned func(error)    // Valid on client-side
 }
 
+func (h *headerFrame) isTransportResponseFrame() bool {
+	return h.cleanup != nil && h.cleanup.rst // Results in a RST_STREAM
+}
+
 type cleanupStream struct {
 	streamID uint32
 	rst      bool
@@ -109,6 +126,8 @@
 	onWrite  func()
 }
 
+func (c *cleanupStream) isTransportResponseFrame() bool { return c.rst } // Results in a RST_STREAM
+
 type dataFrame struct {
 	streamID  uint32
 	endStream bool
@@ -119,27 +138,41 @@
 	onEachWrite func()
 }
 
+func (*dataFrame) isTransportResponseFrame() bool { return false }
+
 type incomingWindowUpdate struct {
 	streamID  uint32
 	increment uint32
 }
 
+func (*incomingWindowUpdate) isTransportResponseFrame() bool { return false }
+
 type outgoingWindowUpdate struct {
 	streamID  uint32
 	increment uint32
 }
 
+func (*outgoingWindowUpdate) isTransportResponseFrame() bool {
+	return false // window updates are throttled by thresholds
+}
+
 type incomingSettings struct {
 	ss []http2.Setting
 }
 
+func (*incomingSettings) isTransportResponseFrame() bool { return true } // Results in a settings ACK
+
 type outgoingSettings struct {
 	ss []http2.Setting
 }
 
+func (*outgoingSettings) isTransportResponseFrame() bool { return false }
+
 type incomingGoAway struct {
 }
 
+func (*incomingGoAway) isTransportResponseFrame() bool { return false }
+
 type goAway struct {
 	code      http2.ErrCode
 	debugData []byte
@@ -147,15 +180,21 @@
 	closeConn bool
 }
 
+func (*goAway) isTransportResponseFrame() bool { return false }
+
 type ping struct {
 	ack  bool
 	data [8]byte
 }
 
+func (*ping) isTransportResponseFrame() bool { return true }
+
 type outFlowControlSizeRequest struct {
 	resp chan uint32
 }
 
+func (*outFlowControlSizeRequest) isTransportResponseFrame() bool { return false }
+
 type outStreamState int
 
 const (
@@ -238,6 +277,14 @@
 	consumerWaiting bool
 	list            *itemList
 	err             error
+
+	// transportResponseFrames counts the number of queued items that represent
+	// the response of an action initiated by the peer.  trfChan is created
+	// when transportResponseFrames >= maxQueuedTransportResponseFrames and is
+	// closed and nilled when transportResponseFrames drops below the
+	// threshold.  Both fields are protected by mu.
+	transportResponseFrames int
+	trfChan                 atomic.Value // *chan struct{}
 }
 
 func newControlBuffer(done <-chan struct{}) *controlBuffer {
@@ -248,12 +295,24 @@
 	}
 }
 
-func (c *controlBuffer) put(it interface{}) error {
+// throttle blocks if there are too many incomingSettings/cleanupStreams in the
+// controlbuf.
+func (c *controlBuffer) throttle() {
+	ch, _ := c.trfChan.Load().(*chan struct{})
+	if ch != nil {
+		select {
+		case <-*ch:
+		case <-c.done:
+		}
+	}
+}
+
+func (c *controlBuffer) put(it cbItem) error {
 	_, err := c.executeAndPut(nil, it)
 	return err
 }
 
-func (c *controlBuffer) executeAndPut(f func(it interface{}) bool, it interface{}) (bool, error) {
+func (c *controlBuffer) executeAndPut(f func(it interface{}) bool, it cbItem) (bool, error) {
 	var wakeUp bool
 	c.mu.Lock()
 	if c.err != nil {
@@ -271,6 +330,15 @@
 		c.consumerWaiting = false
 	}
 	c.list.enqueue(it)
+	if it.isTransportResponseFrame() {
+		c.transportResponseFrames++
+		if c.transportResponseFrames == maxQueuedTransportResponseFrames {
+			// We are adding the frame that puts us over the threshold; create
+			// a throttling channel.
+			ch := make(chan struct{})
+			c.trfChan.Store(&ch)
+		}
+	}
 	c.mu.Unlock()
 	if wakeUp {
 		select {
@@ -304,7 +372,17 @@
 			return nil, c.err
 		}
 		if !c.list.isEmpty() {
-			h := c.list.dequeue()
+			h := c.list.dequeue().(cbItem)
+			if h.isTransportResponseFrame() {
+				if c.transportResponseFrames == maxQueuedTransportResponseFrames {
+					// We are removing the frame that put us over the
+					// threshold; close and clear the throttling channel.
+					ch := c.trfChan.Load().(*chan struct{})
+					close(*ch)
+					c.trfChan.Store((*chan struct{})(nil))
+				}
+				c.transportResponseFrames--
+			}
 			c.mu.Unlock()
 			return h, nil
 		}
@@ -559,21 +637,17 @@
 
 func (l *loopyWriter) originateStream(str *outStream) error {
 	hdr := str.itl.dequeue().(*headerFrame)
-	sendPing, err := hdr.initStream(str.id)
-	if err != nil {
+	if err := hdr.initStream(str.id); err != nil {
 		if err == ErrConnClosing {
 			return err
 		}
 		// Other errors(errStreamDrain) need not close transport.
 		return nil
 	}
-	if err = l.writeHeader(str.id, hdr.endStream, hdr.hf, hdr.onWrite); err != nil {
+	if err := l.writeHeader(str.id, hdr.endStream, hdr.hf, hdr.onWrite); err != nil {
 		return err
 	}
 	l.estdStreams[str.id] = str
-	if sendPing {
-		return l.pingHandler(&ping{data: [8]byte{}})
-	}
 	return nil
 }