fixup! erts: Fair handover of code permissions to first waiter

Author: sverker

erts/emulator/beam/code_ix.h

@@ -174,10 +174,10 @@ ErtsCodeIndex erts_staging_code_ix(void);
  * Main process lock (only) must be held.
  * System thread progress must not be blocked.
  * Caller must not already have the code modification or staging permissions.
- * Caller is suspended and *must* yield if 0 is returned. */
+ * Caller is suspended and *must* yield if false is returned. */
 bool erts_try_seize_code_load_permission(struct process* c_p);
 
-/** @brief Release code loading permission. Resumes any suspended waiters. */
+/** @brief Release code loading permission. Resumes first suspended waiters. */
 void erts_release_code_load_permission(void);
 
 /** @brief Try to seize exclusive code staging permission. Needed for code

erts/emulator/test/code_SUITE.erl

@@ -533,8 +533,8 @@ code_permission(_Config) ->
                         Tester ! {self(), unlocked}
                 end,
     Locker1 = spawn_link(LockerFun),
-    {Locker2, MRef2} = spawn_monitor(LockerFun),
-    {Locker3, MRef3} = spawn_monitor(LockerFun),
+    {Locker2, MRef2} = spawn_opt(LockerFun,[link,monitor]),
+    {Locker3, MRef3} = spawn_opt(LockerFun,[link,monitor]),
     Locker4 = spawn_link(LockerFun),
     Locker5 = spawn_link(LockerFun),
 
@@ -560,13 +560,15 @@ code_permission(_Config) ->
         wait_suspended(Locker5),
 
         %% Test killing process waiting in queue
+        unlink(Locker3),
         exit_signal(Locker3, kill),
         {'DOWN', MRef3, process, Locker3, killed} = receive_any(),
 
         Locker1 ! unlock,
         {Locker1, unlocked} = receive_any(),
 
         %% Test killing process after lock handover but before getting scheduled
+        unlink(Locker2),
         exit_signal(Locker2, kill),
         receive {'DOWN', MRef2, process, Locker2, killed} -> ok end,
 
@@ -1611,4 +1613,7 @@ run_sys_proc_test(Test, Config) ->
     end.
 
 receive_any() ->
-    receive M -> M end.
+    receive M -> M
+    after 10_000 ->
+            ct:fail({timeout, receive_any})
+    end.

erts/emulator/test/code_SUITE_data/erts_test_sync_tracer.c

@@ -84,9 +84,6 @@ static ERL_NIF_TERM nifs_loaded(ErlNifEnv* env, int argc, const ERL_NIF_TERM arg
 
 static ERL_NIF_TERM enabled(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
-    int state_arity;
-    const ERL_NIF_TERM *state_tuple;
-    ERL_NIF_TERM value;
     ASSERT(argc == 3);
 
     //enif_fprintf(stderr, "erts_test_sync_tracer.enabled(%T, %T, %T)\n",
@@ -145,9 +142,7 @@ static void do_wait_for_sync(ERL_NIF_TERM wait_for)
 
 static ERL_NIF_TERM trace(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
-    const ERL_NIF_TERM traceTag = argv[0];
     const ERL_NIF_TERM tracerState = argv[1];
-    const ERL_NIF_TERM tracee = argv[2];
     ErlNifPid to;
 
     ASSERT(argc == 5);
@@ -163,7 +158,7 @@ static ERL_NIF_TERM trace(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 
     // Sending a message does not work as it will probably be enqueued
     // and not sent until we are scheduled out.
-    //enif_send(env, &to, NULL, enif_make_tuple2(env, tracee, traceTag));
+    //enif_send(env, &to, NULL, enif_make_tuple2(env, argv[2], argv[0]));
 
     erts_internal_test.ethr_atomic_set(&the_sync, atom_true);
     do_wait_for_sync(atom_false);