From 382adc9e5d7c7dbd4e1f12adc483bc6eb7ed6c3d Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Fri, 8 Jul 2016 15:37:05 +0200
Subject: erts: Optimize db_finalize_dbterm_hash

Always free term after WUNLOCK_HASH
---
 erts/emulator/beam/erl_db_hash.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index 74979f984a..6b23be1adf 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -2910,6 +2910,7 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle)
     HashDbTerm **bp = (HashDbTerm **) handle->bp;
     HashDbTerm *b = *bp;
     erts_smp_rwmtx_t* lck = (erts_smp_rwmtx_t*) handle->lck;
+    HashDbTerm* free_me = NULL;
 
     ERTS_SMP_LC_ASSERT(IS_HASH_WLOCKED(tb, lck));  /* locked by db_lookup_dbterm_hash */
 
@@ -2921,7 +2922,7 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle)
             b->hvalue = INVALID_HASH;
         } else {
             *bp = b->next;
-            free_term(tb, b);
+            free_me = b;
         }
 
         WUNLOCK_HASH(lck);
@@ -2930,12 +2931,15 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle)
     } else if (handle->flags & DB_MUST_RESIZE) {
 	db_finalize_resize(handle, offsetof(HashDbTerm,dbterm));
 	WUNLOCK_HASH(lck);
-
-	free_term(tb, b);
+        free_me = b;
     }
     else {
 	WUNLOCK_HASH(lck);
     }
+
+    if (free_me)
+        free_term(tb, free_me);
+
 #ifdef DEBUG
     handle->dbterm = 0;
 #endif
-- 
cgit v1.2.3


From a6d87854c3ae65dba8dba6571b4d31d901316a39 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Fri, 8 Jul 2016 15:13:35 +0200
Subject: erts: Fix deadlock in ets:update_counter/4

in 'set' with 'write_concurrency'
when inserting default object causes table to grow
and the bucket to split is protected by same lock as the key.
---
 erts/emulator/beam/erl_db_hash.c | 34 ++++++++++++++++++----------------
 erts/emulator/beam/erl_db_util.h |  1 +
 2 files changed, 19 insertions(+), 16 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index 6b23be1adf..12ae086b31 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -2866,15 +2866,7 @@ db_lookup_dbterm_hash(Process *p, DbTable *tbl, Eterm key, Eterm obj,
             q->hvalue = hval;
             q->next = NULL;
             *bp = b = q;
-
-            {
-                int nitems = erts_smp_atomic_inc_read_nob(&tb->common.nitems);
-                int nactive = NACTIVE(tb);
-
-                if (nitems > nactive * (CHAIN_LEN + 1) && !IS_FIXED(tb)) {
-                    grow(tb, nactive);
-                }
-            }
+            flags |= DB_INC_TRY_GROW;
         } else {
             HashDbTerm *q, *next = b->next;
 
@@ -2928,13 +2920,23 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle)
         WUNLOCK_HASH(lck);
         erts_smp_atomic_dec_nob(&tb->common.nitems);
         try_shrink(tb);
-    } else if (handle->flags & DB_MUST_RESIZE) {
-	db_finalize_resize(handle, offsetof(HashDbTerm,dbterm));
-	WUNLOCK_HASH(lck);
-        free_me = b;
-    }
-    else {
-	WUNLOCK_HASH(lck);
+    } else {
+        if (handle->flags & DB_MUST_RESIZE) {
+            db_finalize_resize(handle, offsetof(HashDbTerm,dbterm));
+            free_me = b;
+        }
+        if (handle->flags & DB_INC_TRY_GROW) {
+            int nactive;
+            int nitems = erts_smp_atomic_inc_read_nob(&tb->common.nitems);
+            WUNLOCK_HASH(lck);
+            nactive = NACTIVE(tb);
+
+            if (nitems > nactive * (CHAIN_LEN + 1) && !IS_FIXED(tb)) {
+                grow(tb, nactive);
+            }
+        } else {
+            WUNLOCK_HASH(lck);
+        }
     }
 
     if (free_me)
diff --git a/erts/emulator/beam/erl_db_util.h b/erts/emulator/beam/erl_db_util.h
index 60f7067d70..4acedbfed0 100644
--- a/erts/emulator/beam/erl_db_util.h
+++ b/erts/emulator/beam/erl_db_util.h
@@ -79,6 +79,7 @@ typedef union db_table DbTable;
 
 #define DB_MUST_RESIZE 1
 #define DB_NEW_OBJECT 2
+#define DB_INC_TRY_GROW 4
 
 /* Info about a database entry while it's being updated
  * (by update_counter or update_element)
-- 
cgit v1.2.3