Fix broken assertion on monitor release

We sometimes bump the refc without messing with the table, which
means that we sometimes decrement it while in the table, causing
the old assertion to fail.

The property we want to check is that neither end of the monitor is
present in the table when the monitor is deleted.

1 files changed, 10 insertions, 5 deletions

diff --git a/erts/emulator/beam/erl_monitor_link.h b/erts/emulator/beam/erl_monitor_link.h
index 9ff8aa509a..ed7bf7d54a 100644
--- a/erts/emulator/beam/erl_monitor_link.h
+++ b/erts/emulator/beam/erl_monitor_link.h
@@ -1387,11 +1387,14 @@ ERTS_GLB_INLINE void
 erts_monitor_release(ErtsMonitor *mon)
 {
     ErtsMonitorData *mdp = erts_monitor_to_data(mon);
-    ERTS_ML_ASSERT(!(mon->flags & ERTS_ML_FLG_IN_TABLE));
     ERTS_ML_ASSERT(erts_atomic32_read_nob(&mdp->refc) > 0);
 
-    if (erts_atomic32_dec_read_nob(&mdp->refc) == 0)
+    if (erts_atomic32_dec_read_nob(&mdp->refc) == 0) {
+        ERTS_ML_ASSERT(!(mdp->origin.flags & ERTS_ML_FLG_IN_TABLE));
+        ERTS_ML_ASSERT(!(mdp->target.flags & ERTS_ML_FLG_IN_TABLE));
+
         erts_monitor_destroy__(mdp);
+    }
 }
 
 ERTS_GLB_INLINE void
@@ -1399,12 +1402,14 @@ erts_monitor_release_both(ErtsMonitorData *mdp)
 {
     ERTS_ML_ASSERT((mdp->origin.flags & ERTS_ML_FLGS_SAME)
                    == (mdp->target.flags & ERTS_ML_FLGS_SAME));
-    ERTS_ML_ASSERT(!(mdp->origin.flags & ERTS_ML_FLG_IN_TABLE));
-    ERTS_ML_ASSERT(!(mdp->target.flags & ERTS_ML_FLG_IN_TABLE));
     ERTS_ML_ASSERT(erts_atomic32_read_nob(&mdp->refc) >= 2);
 
-    if (erts_atomic32_add_read_nob(&mdp->refc, (erts_aint32_t) -2) == 0)
+    if (erts_atomic32_add_read_nob(&mdp->refc, (erts_aint32_t) -2) == 0) {
+        ERTS_ML_ASSERT(!(mdp->origin.flags & ERTS_ML_FLG_IN_TABLE));
+        ERTS_ML_ASSERT(!(mdp->target.flags & ERTS_ML_FLG_IN_TABLE));
+
         erts_monitor_destroy__(mdp);
+    }
 }
 
 ERTS_GLB_INLINE int