Avoid scheduling of processes being garbage collected by others

4 files changed, 81 insertions, 25 deletions

diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index 6ae9736141..b6893ff547 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 f01580eb2b..53a18cb2e9 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -3217,20 +3217,32 @@ 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 21625921d5..8c3d21b98f 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -3889,21 +3889,9 @@ 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;
@@ -3930,7 +3918,7 @@ 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 {
@@ -3994,6 +3982,8 @@ 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);
     }
@@ -4006,6 +3996,35 @@ 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
@@ -4119,6 +4138,21 @@ 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 */
 
 /*
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 *,