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File 0775-erts-Test-ensuring-that-dist-spawn-init-message-orde.patch of Package erlang (Revision e9e9df5cd07247af20e8ef23ec8a4cab)

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From 51926794c62c348def0c06f2b2981b59ac220902 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Mon, 9 Oct 2023 18:23:38 +0200
Subject: [PATCH] [erts] Test ensuring that dist spawn init message order is
 preserved

---
 erts/emulator/beam/erl_process.c     | 15 ++++++
 erts/emulator/test/process_SUITE.erl | 73 +++++++++++++++++++++++++++-
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 3e6173429a..736091b163 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -12742,6 +12742,21 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
         erts_queue_message(p, locks, erts_alloc_message(0, NULL),
                            am_dist_spawn_init, am_system);
 
+        /*
+         * The process was created with msgq-lock locked and no siq-inq
+         * buffers installed. The msgq-lock has not been released, so
+         * sig-inq buffers cannot have been installed yet. Since the
+         * above messages already exist in the *single* outer signal
+         * queue, no other messages can be reordered past them...
+         */
+        ASSERT(erts_atomic_read_nob(&p->sig_inq_buffers) == (erts_aint_t)NULL);
+
+        /*
+         * ... but we anyway move the messages into the message queue
+         * since we already got the msgq-lock at this point.
+         */
+        erts_proc_sig_fetch(p);
+
         erts_proc_unlock(p, locks & ERTS_PROC_LOCKS_ALL_MINOR);
     
         if (so->flags & SPO_LINK) {
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 080b63c5f6..143e6247c1 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -92,6 +92,7 @@
          spawn_old_node/1,
          spawn_new_node/1,
          spawn_request_reply_option/1,
+         dist_spawn_arg_list_mixup/1,
          alias_bif/1,
          dist_frag_alias/1,
          dist_frag_unaliased/1,
@@ -151,6 +152,8 @@ groups() ->
      spawn_old_node,
      spawn_new_node,
      spawn_request_reply_option,
+     spawn_request_reply_option,
+     dist_spawn_arg_list_mixup,
      otp_6237,
      {group, processes_bif},
      {group, otp_7738}, garb_other_running,
@@ -3918,6 +3920,75 @@ spawn_request_reply_option_test(Peer, Node) ->
             ok
     end.
 
+dist_spawn_arg_list_mixup(Config) when is_list(Config) ->
+    %% A process newly spawned via the distribution is passed the
+    %% argument list to use as the first message followed by an intialization
+    %% message. Those two messages *must* be the first messages in its queue
+    %% when it begins execution. The parallel receive/send signal optimization
+    %% could potentially cause reordering of messages if certain future
+    %% changes are made. This test case tries to cause a situation where a
+    %% message reordering potentially could happen, and hopefully will detect
+    %% such problematic changes.
+    Tester = self(),
+    NoScheds = 8,
+    NoSchedsStr = integer_to_list(NoScheds),
+    NoSchedsList = lists:seq(1, NoScheds),
+    {ok, Peer, Node} = ?CT_PEER(["+S"++NoSchedsStr++":"++NoSchedsStr]),
+    AttackMsg = make_ref(),
+    AttackArgList = [Tester, AttackMsg],
+    OkMsg = make_ref(),
+    As = lists:map(
+           fun (_) ->
+                   spawn_opt(
+                     Node,
+                     fun () ->
+                             dist_spawn_arg_list_mixup_sender(AttackArgList,
+                                                              1000)
+                     end, [{priority, high}, link])
+           end, NoSchedsList),
+    Relay = spawn_opt(
+              Node,
+              fun () ->
+                      receive
+                          {attack, Victim} ->
+                              lists:foreach(fun (A) ->
+                                                    A ! {attack, Victim}
+                                            end, As)
+                      end
+              end, [{priority, max}, link]),
+    receive after 100 -> ok end,
+    Victim = spawn_opt(Node, erlang, send, [Tester, OkMsg],
+                       [{message_queue_data, off_heap},
+                        {priority, normal},
+                        link]),
+    Relay ! {attack, Victim},
+    receive
+        OkMsg ->
+            ok;
+        AttackMsg ->
+            ct:fail(child_process_used_message_as_argument_list)
+    end,
+    lists:foreach(fun (P) ->
+                          unlink(P)
+                  end, [Victim] ++ [Relay] ++ As),
+    peer:stop(Peer),
+    ok.
+
+dist_spawn_arg_list_mixup_sender(Msg, N) ->
+    receive
+        {attack, Victim} ->
+            dist_spawn_arg_list_mixup_sender(Victim, Msg, N)
+    after
+        0 ->
+            dist_spawn_arg_list_mixup_sender(Msg, N)
+    end.
+
+dist_spawn_arg_list_mixup_sender(_Pid, _Msg, 0) ->
+    ok;
+dist_spawn_arg_list_mixup_sender(Pid, Msg, N) ->
+    Pid ! Msg,
+    dist_spawn_arg_list_mixup_sender(Pid, Msg, N-1).
+
 processes_term_proc_list(Config) when is_list(Config) ->
     Tester = self(),
 
-- 
2.35.3

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File 0775-erts-Test-ensuring-that-dist-spawn-init-message-orde.patch of Package erlang (Revision e9e9df5cd07247af20e8ef23ec8a4cab)

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