kernel: Guarantee that signal server will always run

erlang · Oct 15, 2024 · 2a45d46 · 2a45d46
1 parent 4c5a367
commit 2a45d46
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Showing 3 changed files with 12 additions and 17 deletions.
diff --git a/lib/kernel/src/erl_signal_handler.erl b/lib/kernel/src/erl_signal_handler.erl
@@ -29,12 +29,7 @@
 
 start() ->
     %% add signal handler
-    case whereis(erl_signal_server) of
-        %% in case of minimal mode
-        undefined -> ok;
-        _ ->
-            gen_event:add_handler(erl_signal_server, erl_signal_handler, [])
-    end.
+    gen_event:add_handler(erl_signal_server, erl_signal_handler, []).
 
 init(_Args) ->
     {ok, #state{}}.

diff --git a/lib/kernel/src/kernel.erl b/lib/kernel/src/kernel.erl
@@ -133,6 +133,14 @@ init([]) ->
                type => worker,
                modules => [?MODULE]},
 
+    %% Must be started before user
+    SigSrv = #{id => erl_signal_server,
+               start => {gen_event, start_link, [{local, erl_signal_server}]},
+               restart => permanent,
+               shutdown => 2000,
+               type => worker,
+               modules => dynamic},
+
     User = #{id => user,
              start => {user_sup, start, []},
              restart => temporary,
@@ -187,7 +195,7 @@ init([]) ->
             {ok, {SupFlags,
                   [Code, StdError | EarlyFile] ++
                       [OnLoad | LateFile] ++
-                      Peer ++
+                      [SigSrv | Peer] ++
                       [User, LoggerSup, Config, RefC, SafeSup]}};
         _ ->
             DistChildren =
@@ -203,13 +211,6 @@ init([]) ->
                        type => worker,
                        modules => [inet_db]},
 
-            SigSrv = #{id => erl_signal_server,
-                       start => {gen_event, start_link, [{local, erl_signal_server}]},
-                       restart => permanent,
-                       shutdown => 2000,
-                       type => worker,
-                       modules => dynamic},
-
             Timer = start_timer(),
             CompileServer = start_compile_server(),
 

diff --git a/lib/kernel/src/prim_tty.erl b/lib/kernel/src/prim_tty.erl
@@ -327,9 +327,8 @@ init_term(State = #state{ tty = TTY, options = Options }) ->
     %%
     %% After SIGCONT and SIGWINCH support was added, this module uses a
     %% gen_event handler in `prim_tty_sighandler'.
-    case {ReaderState#state.reader, erlang:whereis(erl_signal_server)} of
-        {{_ReaderPid, ReaderRef}, EssPid}
-          when is_reference(ReaderRef) andalso is_pid(EssPid) ->
+    case ReaderState#state.reader of
+        {_ReaderPid, ReaderRef} when is_reference(ReaderRef) ->
             _ = gen_event:delete_handler(
                   erl_signal_server, prim_tty_sighandler,
                   undefined),