Merge branch 'sverker/erts/ets-memstat-false-leak/ERL-720/OTP-15278' into maint

* sverker/erts/ets-memstat-false-leak/ERL-720/OTP-15278:
  erts: Refactor ets FixedDeletion allocations
  erts: Fix ets memstat false leak of FixedDeletion

2 files changed, 67 insertions, 23 deletions

diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index b988a19cf4..752d3ae3a8 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -150,6 +150,22 @@ static ERTS_INLINE Uint hash_to_ix(DbTableHash* tb, HashValue hval)
 }
 
 
+static ERTS_INLINE FixedDeletion* alloc_fixdel(DbTableHash* tb)
+{
+    FixedDeletion* fixd = (FixedDeletion*) erts_db_alloc(ERTS_ALC_T_DB_FIX_DEL,
+                                                         (DbTable *) tb,
+                                                         sizeof(FixedDeletion));
+    ERTS_ETS_MISC_MEM_ADD(sizeof(FixedDeletion));
+    return fixd;
+}
+
+static ERTS_INLINE void free_fixdel(DbTableHash* tb, FixedDeletion* fixd)
+{
+    erts_db_free(ERTS_ALC_T_DB_FIX_DEL, (DbTable*)tb,
+                 fixd, sizeof(FixedDeletion));
+    ERTS_ETS_MISC_MEM_ADD(-sizeof(FixedDeletion));
+}
+
 static ERTS_INLINE int link_fixdel(DbTableHash* tb,
                                    FixedDeletion* fixd,
                                    erts_aint_t fixated_by_me)
@@ -160,8 +176,7 @@ static ERTS_INLINE int link_fixdel(DbTableHash* tb,
     was_next = erts_atomic_read_acqb(&tb->fixdel);
     do { /* Lockless atomic insertion in linked list: */
         if (NFIXED(tb) <= fixated_by_me) {
-            erts_db_free(ERTS_ALC_T_DB_FIX_DEL, (DbTable*)tb,
-                         fixd, sizeof(FixedDeletion));
+            free_fixdel(tb, fixd);
             return 0; /* raced by unfixer */
         }
         exp_next = was_next;
@@ -180,10 +195,7 @@ static ERTS_INLINE int link_fixdel(DbTableHash* tb,
 static int add_fixed_deletion(DbTableHash* tb, int ix,
                               erts_aint_t fixated_by_me)
 {
-    FixedDeletion* fixd = (FixedDeletion*) erts_db_alloc(ERTS_ALC_T_DB_FIX_DEL,
-							 (DbTable *) tb,
-							 sizeof(FixedDeletion));
-    ERTS_ETS_MISC_MEM_ADD(sizeof(FixedDeletion));
+    FixedDeletion* fixd = alloc_fixdel(tb);
     fixd->slot = ix;
     fixd->all = 0;
     return link_fixdel(tb, fixd, fixated_by_me);
@@ -637,11 +649,7 @@ restart:
 
         free_me = fixdel;
         fixdel = fixdel->next;
-        erts_db_free(ERTS_ALC_T_DB_FIX_DEL,
-                     (DbTable *) tb,
-                     (void *) free_me,
-                     sizeof(FixedDeletion));
-        ERTS_ETS_MISC_MEM_ADD(-sizeof(FixedDeletion));
+        free_fixdel(tb, free_me);
         work++;
     }
 
@@ -2338,11 +2346,10 @@ static SWord db_mark_all_deleted_hash(DbTable *tbl, SWord reds)
     }
     else {
         /* First call */
-        fixdel = erts_db_alloc(ERTS_ALC_T_DB_FIX_DEL,
-                               (DbTable *) tb,
-                               sizeof(FixedDeletion));
-        ERTS_ETS_MISC_MEM_ADD(sizeof(FixedDeletion));
-        link_fixdel(tb, fixdel, 0);
+        int ok;
+        fixdel = alloc_fixdel(tb);
+        ok = link_fixdel(tb, fixdel, 0);
+        ASSERT(ok); (void)ok;
         i = 0;
     }
 
@@ -2444,11 +2451,7 @@ static SWord db_free_table_continue_hash(DbTable *tbl, SWord reds)
 	FixedDeletion *fx = fixdel;
 
 	fixdel = fx->next;
-	erts_db_free(ERTS_ALC_T_DB_FIX_DEL,
-		     (DbTable *) tb,
-		     (void *) fx,
-		     sizeof(FixedDeletion));
-	ERTS_ETS_MISC_MEM_ADD(-sizeof(FixedDeletion));
+        free_fixdel(tb, fx);
 	if (--reds < 0) {
 	    erts_atomic_set_relb(&tb->fixdel, (erts_aint_t)fixdel);
 	    return reds;		/* Not done */
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index 7a48d1d55e..d8912e548c 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -66,7 +66,7 @@
 	 meta_lookup_named_read/1, meta_lookup_named_write/1,
 	 meta_newdel_unnamed/1, meta_newdel_named/1]).
 -export([smp_insert/1, smp_fixed_delete/1, smp_unfix_fix/1, smp_select_delete/1,
-         smp_select_replace/1, otp_8166/1, otp_8732/1]).
+         smp_select_replace/1, otp_8166/1, otp_8732/1, delete_unfix_race/1]).
 -export([exit_large_table_owner/1,
 	 exit_many_large_table_owner/1,
 	 exit_many_tables_owner/1,
@@ -142,7 +142,8 @@ all() ->
      ets_all,
      massive_ets_all,
      take,
-     whereis_table].
+     whereis_table,
+     delete_unfix_race].
 
 groups() ->
     [{new, [],
@@ -5489,6 +5490,46 @@ smp_fixed_delete_do() ->
     %%verify_table_load(T),
     ets:delete(T).
 
+%% ERL-720
+%% Provoke race between ets:delete and table unfix (by select_count)
+%% that caused ets_misc memory counter to indicate false leak.
+delete_unfix_race(Config) when is_list(Config) ->
+    EtsMem = etsmem(),
+    Table = ets:new(t,[set,public,{write_concurrency,true}]),
+    InsertOp =
+        fun() ->
+                receive stop ->
+                        false
+                after 0 ->
+                        ets:insert(Table, {rand:uniform(10)}),
+                        true
+                end
+        end,
+    DeleteOp =
+        fun() ->
+                receive stop ->
+                        false
+                after 0 ->
+                        ets:delete(Table, rand:uniform(10)),
+                        true
+                end
+        end,
+    SelectOp =
+        fun() ->
+                ets:select_count(Table, ets:fun2ms(fun(X) -> true end))
+        end,
+    Main = self(),
+    Ins = spawn(fun()-> repeat_while(InsertOp), Main ! self() end),
+    Del = spawn(fun()-> repeat_while(DeleteOp), Main ! self() end),
+    spawn(fun()->
+                  repeat(SelectOp, 10000),
+                  Del ! stop,
+                  Ins ! stop
+          end),
+    [receive Pid -> ok end || Pid <- [Ins,Del]],
+    ets:delete(Table),
+    verify_etsmem(EtsMem).
+
 num_of_buckets(T) ->
     element(1,ets:info(T,stats)).