Merge branch 'rickard/gc-other/OTP-9211' into dev

* rickard/gc-other/OTP-9211:
  Fix bad assertions
  Avoid scheduling of processes being garbage collected by others

5 files changed, 121 insertions, 29 deletions

diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index 1ca405961f..1dbf6f9b92 100644
--- a/erts/emulator/beam/beam_bif_load.c
+++ b/erts/emulator/beam/beam_bif_load.c
@@ -175,8 +175,12 @@ check_process_code_2(BIF_ALIST_2)
 	Eterm res;
 	if (internal_pid_index(BIF_ARG_1) >= erts_max_processes)
 	    goto error;
-	rp = erts_pid2proc_not_running(BIF_P, ERTS_PROC_LOCK_MAIN,
-				       BIF_ARG_1, ERTS_PROC_LOCK_MAIN);
+#ifdef ERTS_SMP
+	rp = erts_pid2proc_suspend(BIF_P, ERTS_PROC_LOCK_MAIN,
+				   BIF_ARG_1, ERTS_PROC_LOCK_MAIN);
+#else
+	rp = erts_pid2proc(BIF_P, 0, BIF_ARG_1, 0);
+#endif
 	if (!rp) {
 	    BIF_RET(am_false);
 	}
@@ -187,8 +191,10 @@ check_process_code_2(BIF_ALIST_2)
 	modp = erts_get_module(BIF_ARG_2);
 	res = check_process_code(rp, modp);
 #ifdef ERTS_SMP
-	if (BIF_P != rp)
+	if (BIF_P != rp) {
+	    erts_resume(rp, ERTS_PROC_LOCK_MAIN);
 	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MAIN);
+	}
 #endif
 	BIF_RET(res);
     }
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index b3325d635b..8c35644125 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -3215,20 +3215,32 @@ BIF_RETTYPE garbage_collect_1(BIF_ALIST_1)
 	BIF_ERROR(BIF_P, BADARG);
     }
 
-    rp = erts_pid2proc_not_running(BIF_P, ERTS_PROC_LOCK_MAIN,
+    if (BIF_P->id == BIF_ARG_1)
+	rp = BIF_P;
+    else {
+#ifdef ERTS_SMP
+	rp = erts_pid2proc_suspend(BIF_P, ERTS_PROC_LOCK_MAIN,
 				   BIF_ARG_1, ERTS_PROC_LOCK_MAIN);
-    if (!rp)
-	BIF_RET(am_false);
-    if (rp == ERTS_PROC_LOCK_BUSY)
-	ERTS_BIF_YIELD1(bif_export[BIF_garbage_collect_1], BIF_P, BIF_ARG_1);
+	if (rp == ERTS_PROC_LOCK_BUSY)
+	    ERTS_BIF_YIELD1(bif_export[BIF_garbage_collect_1], BIF_P, BIF_ARG_1);
+#else
+	rp = erts_pid2proc(BIF_P, 0, BIF_ARG_1, 0);
+#endif
+	if (!rp)
+	    BIF_RET(am_false);
+    }
 
     /* The GC cost is taken for the process executing this BIF. */
 
     FLAGS(rp) |= F_NEED_FULLSWEEP;
     reds = erts_garbage_collect(rp, 0, rp->arg_reg, rp->arity);
 
-    if (BIF_P != rp)
+#ifdef ERTS_SMP
+    if (BIF_P != rp) {
+	erts_resume(rp, ERTS_PROC_LOCK_MAIN);
 	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MAIN);
+    }
+#endif
 
     BIF_RET2(am_true, reds);
 }
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 31f23d3978..8a56976905 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -3887,21 +3887,9 @@ handle_pend_sync_suspend(Process *suspendee,
     }
 }
 
-/*
- * Like erts_pid2proc() but:
- *
- * * At least ERTS_PROC_LOCK_MAIN have to be held on c_p.
- * * At least ERTS_PROC_LOCK_MAIN have to be taken on pid.
- * * It also waits for proc to be in a state != running and garbing.
- * * If ERTS_PROC_LOCK_BUSY is returned, the calling process has to
- *   yield (ERTS_BIF_YIELD[0-3]()). c_p might in this case have been
- *   suspended.
- */
-
-
-Process *
-erts_pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
-			  Eterm pid, ErtsProcLocks pid_locks)
+static Process *
+pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
+		     Eterm pid, ErtsProcLocks pid_locks, int suspend)
 {
     Process *rp;
     int unlock_c_p_status;
@@ -3928,7 +3916,7 @@ erts_pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
 	c_p->suspendee = NIL;
 	ASSERT(c_p->flags & F_P2PNR_RESCHED);
 	c_p->flags &= ~F_P2PNR_RESCHED;
-	if (rp)
+	if (!suspend && rp)
 	    resume_process(rp);
     }
     else {
@@ -3992,6 +3980,8 @@ erts_pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
 	    }
 
 	    /* rp is not running and we got the locks we want... */
+	    if (suspend)
+		suspend_process(rp_rq, rp);
 	}
 	erts_smp_runqs_unlock(cp_rq, rp_rq);
     }
@@ -4004,6 +3994,35 @@ erts_pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
     return rp;
 }
 
+
+/*
+ * Like erts_pid2proc() but:
+ *
+ * * At least ERTS_PROC_LOCK_MAIN have to be held on c_p.
+ * * At least ERTS_PROC_LOCK_MAIN have to be taken on pid.
+ * * It also waits for proc to be in a state != running and garbing.
+ * * If ERTS_PROC_LOCK_BUSY is returned, the calling process has to
+ *   yield (ERTS_BIF_YIELD[0-3]()). c_p might in this case have been
+ *   suspended.
+ */
+Process *
+erts_pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
+			  Eterm pid, ErtsProcLocks pid_locks)
+{
+    return pid2proc_not_running(c_p, c_p_locks, pid, pid_locks, 0);
+}
+
+/*
+ * Like erts_pid2proc_not_running(), but hands over the process
+ * in a suspended state unless (c_p is looked up).
+ */
+Process *
+erts_pid2proc_suspend(Process *c_p, ErtsProcLocks c_p_locks,
+		      Eterm pid, ErtsProcLocks pid_locks)
+{
+    return pid2proc_not_running(c_p, c_p_locks, pid, pid_locks, 1);
+}
+
 /*
  * erts_pid2proc_nropt() is normally the same as
  * erts_pid2proc_not_running(). However it is only
@@ -4117,6 +4136,21 @@ handle_pend_bif_async_suspend(Process *suspendee,
     }
 }
 
+#else
+
+/*
+ * Non-smp version of erts_pid2proc_suspend().
+ */
+Process *
+erts_pid2proc_suspend(Process *c_p, ErtsProcLocks c_p_locks,
+		      Eterm pid, ErtsProcLocks pid_locks)
+{
+    Process *rp = erts_pid2proc(c_p, c_p_locks, pid, pid_locks);
+    if (rp)
+	erts_suspend(rp, pid_locks, NULL);
+    return rp;
+}
+
 #endif /* ERTS_SMP */
 
 /*
@@ -4650,7 +4684,7 @@ internal_add_to_runq(ErtsRunQueue *runq, Process *p)
     if (p->status_flags & ERTS_PROC_SFLG_INRUNQ)
 	return NULL;
     else if (p->runq_flags & ERTS_PROC_RUNQ_FLG_RUNNING) {
-	ASSERT(p->rcount == 0);
+	ASSERT(ERTS_PROC_IS_EXITING(p) || p->rcount == 0);
 	ERTS_DBG_CHK_PROCS_RUNQ_NOPROC(runq, p);
 	p->status_flags |= ERTS_PROC_SFLG_PENDADD2SCHEDQ;
 	return NULL;
@@ -4661,7 +4695,7 @@ internal_add_to_runq(ErtsRunQueue *runq, Process *p)
     ERTS_DBG_CHK_PROCS_RUNQ_NOPROC(runq, p);
 #ifndef ERTS_SMP
     /* Never schedule a suspended process (ok in smp case) */
-    ASSERT(p->rcount == 0);
+    ASSERT(ERTS_PROC_IS_EXITING(p) || p->rcount == 0);
     add_runq = runq;
 #else
     ASSERT(!p->bound_runq || p->bound_runq == p->run_queue);
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 334ae5573f..296acc7367 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1535,6 +1535,10 @@ erts_get_atom_cache_map(Process *c_p)
 }
 #endif
 
+Process *erts_pid2proc_suspend(Process *,
+			       ErtsProcLocks,
+			       Eterm,
+			       ErtsProcLocks);
 #ifdef ERTS_SMP
 
 Process *erts_pid2proc_not_running(Process *,
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 36bae908aa..f68e712268 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -50,7 +50,8 @@
 	 processes_last_call_trap/1, processes_gc_trap/1,
 	 processes_term_proc_list/1,
 	 otp_7738_waiting/1, otp_7738_suspended/1,
-	 otp_7738_resume/1]).
+	 otp_7738_resume/1,
+	 garb_other_running/1]).
 -export([prio_server/2, prio_client/2]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
@@ -72,7 +73,7 @@ all() ->
      bad_register, garbage_collect, process_info_messages,
      process_flag_badarg, process_flag_heap_size,
      spawn_opt_heap_size, otp_6237, {group, processes_bif},
-     {group, otp_7738}].
+     {group, otp_7738}, garb_other_running].
 
 groups() -> 
     [{t_exit_2, [],
@@ -2116,6 +2117,41 @@ otp_7738_test(Type) ->
 	  end,
     ?line ok.
 
+gor(Reds, Stop) ->
+    receive
+	{From, reds} ->
+	    From ! {reds, Reds, self()},
+	    gor(Reds+1, Stop);
+	{From, Stop} ->
+	    From ! {stopped, Stop, Reds, self()}
+    after 0 ->
+	    gor(Reds+1, Stop)
+    end.
+
+garb_other_running(Config) when is_list(Config) ->
+    ?line Stop = make_ref(),
+    ?line {Pid, Mon} = spawn_monitor(fun () -> gor(0, Stop) end),
+    ?line Reds = lists:foldl(fun (_, OldReds) ->
+				     ?line erlang:garbage_collect(Pid),
+				     ?line receive after 1 -> ok end,
+				     ?line Pid ! {self(), reds},
+				     ?line receive
+					       {reds, NewReds, Pid} ->
+						   ?line true = (NewReds > OldReds),
+						   ?line NewReds
+					   end
+			     end,
+			     0,
+			     lists:seq(1, 10000)),
+    ?line receive after 1 -> ok end,
+    ?line Pid ! {self(), Stop},
+    ?line receive
+	      {stopped, Stop, StopReds, Pid} ->
+		  ?line true = (StopReds > Reds)
+	  end,
+    ?line receive {'DOWN', Mon, process, Pid, normal} -> ok end,
+    ?line ok.
+
 %% Internal functions
 
 wait_until(Fun) ->