From 638476d255cf6f9e5cd880eb9318d5b08664e5f8 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Thu, 15 Oct 2015 11:53:24 +0200
Subject: erts: Allow one dangling fd if there is a gethost port

---
 erts/emulator/test/driver_SUITE.erl | 26 +++++++++++++++++++++++--
 erts/emulator/test/z_SUITE.erl      | 38 ++++++++++++++++++++++++++++++-------
 2 files changed, 55 insertions(+), 9 deletions(-)

diff --git a/erts/emulator/test/driver_SUITE.erl b/erts/emulator/test/driver_SUITE.erl
index b72d6cbe52..e17d0ff96c 100644
--- a/erts/emulator/test/driver_SUITE.erl
+++ b/erts/emulator/test/driver_SUITE.erl
@@ -2395,13 +2395,35 @@ z_test(Config) when is_list(Config) ->
 
 check_io_debug() ->
     get_stable_check_io_info(),
-    {NoErrorFds, NoUsedFds, NoDrvSelStructs, NoDrvEvStructs}
+    {NoErrorFds, NoUsedFds, NoDrvSelStructs, NoDrvEvStructs} = CheckIoDebug
 	= erts_debug:get_internal_state(check_io_debug),
+    HasGetHost = has_gethost(),
+    ct:log("check_io_debug: ~p~n"
+           "HasGetHost: ~p",[CheckIoDebug, HasGetHost]),
     0 = NoErrorFds,
-    NoUsedFds = NoDrvSelStructs,
+    if
+        NoUsedFds == NoDrvSelStructs ->
+            ok;
+        HasGetHost andalso (NoUsedFds == (NoDrvSelStructs - 1)) ->
+            %% If the inet_gethost port is alive, we may have
+            %% one extra used fd that is not selected on
+            ok
+    end,
     0 = NoDrvEvStructs,
     ok.
 
+has_gethost() ->
+    has_gethost(erlang:ports()).
+has_gethost([P|T]) ->
+    case erlang:port_info(P, name) of
+        {name,"inet_gethost"++_} ->
+            true;
+        _ ->
+            has_gethost(T)
+    end;
+has_gethost([]) ->
+    false.
+
 %flush_msgs() ->
 %    receive
 %	M ->
diff --git a/erts/emulator/test/z_SUITE.erl b/erts/emulator/test/z_SUITE.erl
index f4d9030255..abc353fb01 100644
--- a/erts/emulator/test/z_SUITE.erl
+++ b/erts/emulator/test/z_SUITE.erl
@@ -249,6 +249,7 @@ pollset_size(Config) when is_list(Config) ->
     ?line io:format("Initial: ~p~nFinal: ~p~n", [InitChkIo, FinChkIo]),
     ?line InitPollsetSize = lists:keysearch(total_poll_set_size, 1, InitChkIo),
     ?line FinPollsetSize = lists:keysearch(total_poll_set_size, 1, FinChkIo),
+    HasGethost = case has_gethost() of true -> 1; _ -> 0 end,
     ?line case InitPollsetSize =:= FinPollsetSize of
 	      true ->
 		  case InitPollsetSize of
@@ -269,7 +270,7 @@ pollset_size(Config) when is_list(Config) ->
 		      = InitPollsetSize,
 		  ?line {value, {total_poll_set_size, FinSize}}
 		      = FinPollsetSize,
-		  ?line true = FinSize < InitSize,
+		  ?line true = FinSize < (InitSize + HasGethost),
 		  ?line true = 2 =< FinSize,
 		  ?line {comment,
 			 "Start pollset size: "
@@ -289,16 +290,39 @@ check_io_debug(Config) when is_list(Config) ->
 	  end.
 
 check_io_debug_test() ->
-    ?line erlang:display(get_check_io_info()),
-    ?line erts_debug:set_internal_state(available_internal_state, true),
-    ?line {NoErrorFds, NoUsedFds, NoDrvSelStructs, NoDrvEvStructs}
+    erlang:display(get_check_io_info()),
+    erts_debug:set_internal_state(available_internal_state, true),
+    {NoErrorFds, NoUsedFds, NoDrvSelStructs, NoDrvEvStructs} = CheckIoDebug
 	= erts_debug:get_internal_state(check_io_debug),
-    ?line erts_debug:set_internal_state(available_internal_state, false),
-    ?line 0 = NoErrorFds,
-    ?line NoUsedFds = NoDrvSelStructs,
+    erts_debug:set_internal_state(available_internal_state, false),
+    HasGetHost = has_gethost(),
+    ct:log("check_io_debug: ~p~n"
+           "HasGetHost: ~p",[CheckIoDebug, HasGetHost]),
+    0 = NoErrorFds,
+    if
+        NoUsedFds == NoDrvSelStructs ->
+            ok;
+        HasGetHost andalso (NoUsedFds == (NoDrvSelStructs - 1)) ->
+            %% If the inet_gethost port is alive, we may have
+            %% one extra used fd that is not selected on.
+            %% This happens when the initial setup of the
+            %% port returns an EAGAIN
+            ok
+    end,
     ?line 0 = NoDrvEvStructs,
     ?line ok.
 
+has_gethost() ->
+    has_gethost(erlang:ports()).
+has_gethost([P|T]) ->
+    case erlang:port_info(P, name) of
+        {name,"inet_gethost"++_} ->
+            true;
+        _ ->
+            has_gethost(T)
+    end;
+has_gethost([]) ->
+    false.
 
 
 %%
-- 
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