Merge 10.0 into 10.1

1 files changed, 10 insertions, 2 deletions

diff --git a/mysys/hash.c b/mysys/hash.c
index dc03ea9a4dc..d59e63bddc4 100644
--- a/mysys/hash.c
+++ b/mysys/hash.c
@@ -114,14 +114,19 @@ my_hash_init2(HASH *hash, uint growth_size, CHARSET_INFO *charset,
 
 static inline void my_hash_free_elements(HASH *hash)
 {
+  uint records= hash->records;
+  /*
+    Set records to 0 early to guard against anyone looking at the structure
+    during the free process
+  */
+  hash->records= 0;
   if (hash->free)
   {
     HASH_LINK *data=dynamic_element(&hash->array,0,HASH_LINK*);
-    HASH_LINK *end= data + hash->records;
+    HASH_LINK *end= data + records;
     while (data < end)
       (*hash->free)((data++)->data);
   }
-  hash->records=0;
 }
 
 
@@ -518,6 +523,9 @@ my_bool my_hash_insert(HASH *info, const uchar *record)
    The record with the same record ptr is removed.
    If there is a free-function it's called if record was found.
 
+   hash->free() is guarantee to be called only after the row has been
+   deleted from the hash and the hash can be reused by other threads.
+
    @return
    @retval  0  ok
    @retval  1 Record not found