File 0351-Fix-process_info-_-status-from-other-proce... of Package erlang

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File 0351-Fix-process_info-_-status-from-other-process-with-ot.patch of Package erlang (Revision 265b547b5a7ae5e597aaf8c66f401306)

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From 23149c55ed29cd00c260b21c1c74adc33e1b6918 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Thu, 9 Sep 2021 23:39:37 +0200
Subject: [PATCH] Fix process_info(_, status) from other process with other
 prio

---
 erts/emulator/beam/erl_bif_info.c    | 23 +++++++-----
 erts/emulator/beam/erl_process.c     | 52 ++++++++++++++++++++++++++++
 erts/emulator/beam/erl_process.h     |  1 +
 erts/emulator/test/process_SUITE.erl | 22 ++++++++++--
 4 files changed, 87 insertions(+), 11 deletions(-)

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 96f399fbbe..04d625305b 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -1394,17 +1394,22 @@ process_info_aux(Process *c_p,
         if (res == am_running && (state & ERTS_PSFLG_RUNNING_SYS)) {
             ASSERT(c_p == rp);
             ASSERT(flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER);
-            if (!(state & (ERTS_PSFLG_SYS_TASKS
-                           | ERTS_PSFLG_ACTIVE
+            if (!(state & (ERTS_PSFLG_ACTIVE
                            | ERTS_PSFLG_SIG_Q
                            | ERTS_PSFLG_SIG_IN_Q))) {
-                /*
-                 * We are servicing a process-info request from
-                 * another process. If that other process could
-                 * have inspected our state itself, we would have
-                 * been in the 'waiting' state.
-                 */
-                res = am_waiting;
+                int sys_tasks = 0;
+                if (state & ERTS_PSFLG_SYS_TASKS)
+                    sys_tasks = erts_have_non_prio_elev_sys_tasks(rp,
+                                                                  rp_locks);
+                if (!sys_tasks) {
+                    /*
+                     * We are servicing a process-info request from
+                     * another process. If that other process could
+                     * have inspected our state itself, we would have
+                     * been in the 'waiting' state.
+                     */
+                    res = am_waiting;
+                }
             }
         }
 	break;
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 1f464e2e5a..01a2587e78 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -6915,6 +6915,58 @@ erts_proc_sys_schedule(Process *p, erts_aint32_t state, erts_aint32_t enable_fla
     return active_sys_enqueue(p, NULL, 0, enable_flag, state, &fail_state);
 }
 
+int
+erts_have_non_prio_elev_sys_tasks(Process *c_p, ErtsProcLocks locks)
+{
+    ErtsProcSysTaskQs *qs;
+    int res = 0;
+
+    if (!(locks & ERTS_PROC_LOCK_STATUS))
+        erts_proc_lock(c_p, ERTS_PROC_LOCK_STATUS);
+    
+    qs = c_p->sys_task_qs;
+    if (qs) {
+        int qmask = qs->qmask;
+        ASSERT(qmask);
+        while (qmask) {
+            ErtsProcSysTask *st, *first_st;
+            switch (qmask & -qmask) {
+            case MAX_BIT:
+                qmask &= ~MAX_BIT;
+                st = first_st = qs->q[PRIORITY_MAX];
+                break;
+            case HIGH_BIT:
+                qmask &= ~HIGH_BIT;
+                st = first_st = qs->q[PRIORITY_HIGH];
+                break;
+            case NORMAL_BIT:
+            case LOW_BIT:
+                st = first_st = qs->q[PRIORITY_NORMAL];            
+                qmask &= ~(NORMAL_BIT|LOW_BIT);
+                break;
+            default:
+                st = first_st = NULL;
+                break;
+            }
+            ASSERT(st);
+            do {
+                if (st->type != ERTS_PSTT_PRIO_SIG) {
+                    res = !0;
+                    goto done;
+                }
+                st = st->next;
+            } while (st != first_st);
+        }
+    }
+
+done:
+    
+    if (!(locks & ERTS_PROC_LOCK_STATUS))
+        erts_proc_unlock(c_p, ERTS_PROC_LOCK_STATUS);
+
+    return res;
+}
+
 static int
 schedule_process_sys_task(Process *p, erts_aint32_t prio, ErtsProcSysTask *st,
 			  erts_aint32_t *fail_state_p)
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 43937f216c..9b50467340 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1874,6 +1874,7 @@ ErtsSchedulerData *erts_get_scheduler_data(void);
 void erts_schedule_process(Process *, erts_aint32_t, ErtsProcLocks);
 erts_aint32_t erts_proc_sys_schedule(Process *p, erts_aint32_t state,
                                      erts_aint32_t enable_flag);
+int erts_have_non_prio_elev_sys_tasks(Process *c_p, ErtsProcLocks locks);
 
 ERTS_GLB_INLINE void erts_proc_notify_new_message(Process *p, ErtsProcLocks locks);
 ERTS_GLB_INLINE void erts_schedule_dirty_sys_execution(Process *c_p);
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 0cb0d6c1e2..c2bd151eb6 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -38,6 +38,7 @@
 	 exit_and_timeout/1, exit_twice/1,
 	 t_process_info/1, process_info_other/1, process_info_other_msg/1,
 	 process_info_other_dist_msg/1,
+         process_info_other_status/1,
 	 process_info_2_list/1, process_info_lock_reschedule/1,
 	 process_info_lock_reschedule2/1,
 	 process_info_lock_reschedule3/1,
@@ -78,7 +79,8 @@ all() ->
     [spawn_with_binaries, t_exit_1, {group, t_exit_2},
      trap_exit_badarg, trap_exit_badarg_in_bif,
      t_process_info, process_info_other, process_info_other_msg,
-     process_info_other_dist_msg, process_info_2_list,
+     process_info_other_dist_msg, process_info_other_status,
+     process_info_2_list,
      process_info_lock_reschedule,
      process_info_lock_reschedule2,
      process_info_lock_reschedule3,
@@ -650,7 +652,23 @@ process_info_other_dist_msg(Config) when is_list(Config) ->
     Pid ! stop,
     stop_node(Node),
     ok.
-    
+
+process_info_other_status(Config) when is_list(Config) ->
+    %% OTP-17628: status was erroneously reported as 'running',
+    %% when it should be 'waiting', when the priority of the
+    %% caller exceeded the priority of the processes being
+    %% checked (due to prio elevation).
+    Self = self(),
+    Other = spawn_link(fun () -> other_process(Self) end),
+    receive {go_ahead, Other} -> ok end,
+    receive after 100 -> ok end,
+    {status, waiting} = process_info(Other, status),
+    process_flag(priority, high),
+    {status, waiting} = process_info(Other, status),
+    process_flag(priority, max),
+    {status, waiting} = process_info(Other, status),
+    Other ! stop,
+    ok.
 
 other_process(Parent) ->
     self() ! {my,own,message},
-- 
2.31.1

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File 0351-Fix-process_info-_-status-from-other-process-with-ot.patch of Package erlang (Revision 265b547b5a7ae5e597aaf8c66f401306)

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