From 278cc4e5a2552397437999f482bcc4237ed36d35 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Thu, 14 Sep 2017 16:11:27 +0200
Subject: Separate in and out in dist ctrl

---
 lib/ssl/src/inet_tls_dist.erl     |  8 +++--
 lib/ssl/src/ssl_tls_dist_ctrl.erl | 69 ++++++++++++++++++++++++++-------------
 2 files changed, 51 insertions(+), 26 deletions(-)

diff --git a/lib/ssl/src/inet_tls_dist.erl b/lib/ssl/src/inet_tls_dist.erl
index 47f400da6f..65dab189a3 100644
--- a/lib/ssl/src/inet_tls_dist.erl
+++ b/lib/ssl/src/inet_tls_dist.erl
@@ -345,11 +345,13 @@ splitnode(Driver, Node, LongOrShortNames) ->
 	    Host = lists:append(Tail),
 	    check_node(Driver, Name, Node, Host, LongOrShortNames);
 	[_] ->
-	    error_logger:error_msg("** Nodename ~p illegal, no '@' character **~n",
-		      [Node]),
+	    error_logger:error_msg(
+              "** Nodename ~p illegal, no '@' character **~n",
+              [Node]),
 	    ?shutdown(Node);
 	_ ->
-	    error_logger:error_msg("** Nodename ~p illegal **~n", [Node]),
+	    error_logger:error_msg(
+              "** Nodename ~p illegal **~n", [Node]),
 	    ?shutdown(Node)
     end.
 
diff --git a/lib/ssl/src/ssl_tls_dist_ctrl.erl b/lib/ssl/src/ssl_tls_dist_ctrl.erl
index cbb39e71ec..c1d5bc689e 100644
--- a/lib/ssl/src/ssl_tls_dist_ctrl.erl
+++ b/lib/ssl/src/ssl_tls_dist_ctrl.erl
@@ -277,7 +277,7 @@ setup_loop(SslSocket, TickHandler, Sup) ->
             Res =
                 ssl:setopts(
                   SslSocket,
-                  [{active, false}, {packet, 4}, inet_tls_dist:nodelay()]),
+                  [{packet, 4}, inet_tls_dist:nodelay()]),
             From ! {Ref, Res},
             setup_loop(SslSocket, TickHandler, Sup);
 
@@ -285,7 +285,7 @@ setup_loop(SslSocket, TickHandler, Sup) ->
             Res =
                 ssl:setopts(
                   SslSocket,
-                  [{active, once}, {packet, 4}, inet_tls_dist:nodelay()]),
+                  [{packet, 4}, inet_tls_dist:nodelay()]),
             From ! {Ref, Res},
             setup_loop(SslSocket, TickHandler, Sup);
 
@@ -296,30 +296,33 @@ setup_loop(SslSocket, TickHandler, Sup) ->
         {Ref, From, {handshake_complete, _Node, DHandle}} ->
             From ! {Ref, ok},
             %% Handshake complete! Begin dispatching traffic...
+            %%
+            %% Use a dedicated input process to push the
+            %% input-output-flow-control-deadlock problem
+            %% to the SSL implementation.
+            InputHandler =
+                spawn_opt(
+                  fun () ->
+                          link(Sup),
+                          ssl:setopts(SslSocket, [{active, once}]),
+                          receive
+                              DHandle ->
+                                  input_loop(DHandle, SslSocket)
+                          end
+                  end,
+                  [link] ++ common_spawn_opts()),
+            ok = ssl:controlling_process(SslSocket, InputHandler),
+            ok = erlang:dist_ctrl_input_handler(DHandle, InputHandler),
+            InputHandler ! DHandle,
+            %%
             %% From now on we execute on normal priority
             process_flag(priority, normal),
             erlang:dist_ctrl_get_data_notification(DHandle),
-            loop(DHandle, SslSocket)
+            output_loop(DHandle, SslSocket)
     end.
 
-loop(DHandle, SslSocket) ->
+input_loop(DHandle, SslSocket) ->
     receive
-        dist_data ->
-            %% Outgoing data from this node...
-            try send_data(DHandle, SslSocket)
-            catch _ : _ -> death_row()
-            end,
-            loop(DHandle, SslSocket);
-
-        {send, From, Ref, Data} ->
-            %% This is for testing only!
-            %%
-            %% Needed by some OTP distribution
-            %% test suites...
-            sock_send(SslSocket, Data),
-            From ! {Ref, ok},
-            loop(DHandle, SslSocket);
-
         {ssl_closed, SslSocket} ->
             %% Connection to remote node terminated...
             exit(connection_closed);
@@ -330,13 +333,33 @@ loop(DHandle, SslSocket) ->
             %% Incoming data from remote node...
             ok = ssl:setopts(SslSocket, [{active, once}]),
             try erlang:dist_ctrl_put_data(DHandle, Data)
-            catch _ : _ -> death_row()
+            catch _:_ -> death_row()
             end,
-            loop(DHandle, SslSocket);
+            input_loop(DHandle, SslSocket);
+        _ ->
+            %% Drop garbage message...
+            input_loop(DHandle, SslSocket)
+    end.
 
+output_loop(DHandle, SslSocket) ->
+    receive
+        dist_data ->
+            %% Outgoing data from this node...
+            try send_data(DHandle, SslSocket)
+            catch _ : _ -> death_row()
+            end,
+            output_loop(DHandle, SslSocket);
+        {send, From, Ref, Data} ->
+            %% This is for testing only!
+            %%
+            %% Needed by some OTP distribution
+            %% test suites...
+            sock_send(SslSocket, Data),
+            From ! {Ref, ok},
+            output_loop(DHandle, SslSocket);
         _ ->
             %% Drop garbage message...
-            loop(DHandle, SslSocket)
+            output_loop(DHandle, SslSocket)
     end.
 
 send_data(DHandle, SslSocket) ->
-- 
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