Merge pull request #322 from ctiller/http

Prevent a potential deadlock

src/core/transport/chttp2_transport.c

@@ -237,6 +237,9 @@ struct transport {
   /* state for a stream that's not yet been created */
   grpc_stream_op_buffer new_stream_sopb;
 
+  /* stream ops that need to be destroyed, but outside of the lock */
+  grpc_stream_op_buffer nuke_later_sopb;
+
   /* active parser */
   void *parser_data;
   stream *incoming_stream;
@@ -370,6 +373,8 @@ static void unref_transport(transport *t) {
   }
   gpr_free(t->pending_goaways);
 
+  grpc_sopb_destroy(&t->nuke_later_sopb);
+
   gpr_free(t);
 }
 
@@ -416,6 +421,7 @@ static void init_transport(transport *t, grpc_transport_setup_callback setup,
   t->cap_pending_goaways = 0;
   gpr_slice_buffer_init(&t->outbuf);
   gpr_slice_buffer_init(&t->qbuf);
+  grpc_sopb_init(&t->nuke_later_sopb);
   if (is_client) {
     gpr_slice_buffer_add(&t->qbuf,
                          gpr_slice_from_copied_string(CLIENT_CONNECT_STRING));
@@ -555,6 +561,11 @@ static int init_stream(grpc_transport *gt, grpc_stream *gs,
   return 0;
 }
 
+static void schedule_nuke_sopb(transport *t, grpc_stream_op_buffer *sopb) {
+  grpc_sopb_append(&t->nuke_later_sopb, sopb->ops, sopb->nops);
+  sopb->nops = 0;
+}
+
 static void destroy_stream(grpc_transport *gt, grpc_stream *gs) {
   transport *t = (transport *)gt;
   stream *s = (stream *)gs;
@@ -681,6 +692,11 @@ static void unlock(transport *t) {
   int i;
   pending_goaway *goaways = NULL;
   grpc_endpoint *ep = t->ep;
+  grpc_stream_op_buffer nuke_now = t->nuke_later_sopb;
+
+  if (nuke_now.nops) {
+    memset(&t->nuke_later_sopb, 0, sizeof(t->nuke_later_sopb));
+  }
 
   /* see if we need to trigger a write - and if so, get the data ready */
   if (ep && !t->writing) {
@@ -750,6 +766,10 @@ static void unlock(transport *t) {
     unref_transport(t);
   }
 
+  if (nuke_now.nops) {
+    grpc_sopb_destroy(&nuke_now);
+  }
+
   gpr_free(goaways);
 }
 
@@ -1006,9 +1026,9 @@ static void cancel_stream_inner(transport *t, stream *s, gpr_uint32 id,
 
   if (s) {
     /* clear out any unreported input & output: nobody cares anymore */
-    grpc_sopb_reset(&s->parser.incoming_sopb);
     had_outgoing = s->outgoing_sopb.nops != 0;
-    grpc_sopb_reset(&s->outgoing_sopb);
+    schedule_nuke_sopb(t, &s->parser.incoming_sopb);
+    schedule_nuke_sopb(t, &s->outgoing_sopb);
     if (s->cancelled) {
       send_rst = 0;
     } else if (!s->read_closed || !s->sent_write_closed || had_outgoing) {
@@ -1739,8 +1759,8 @@ static void add_to_pollset(grpc_transport *gt, grpc_pollset *pollset) {
 
 static const grpc_transport_vtable vtable = {
     sizeof(stream), init_stream, send_batch, set_allow_window_updates,
-    add_to_pollset,  destroy_stream, abort_stream,     goaway,
-    close_transport, send_ping,      destroy_transport};
+    add_to_pollset, destroy_stream, abort_stream, goaway, close_transport,
+    send_ping, destroy_transport};
 
 void grpc_create_chttp2_transport(grpc_transport_setup_callback setup,
                                   void *arg,