bzr push into mysql-trunk branch (mikael.ronstrom:3875 to 3877)

[Mikael Ronstrom]

 3877 Mikael Ronstrom	2012-04-05
      Minor fix for LOCK_open release

    modified:
      sql/sql_base.cc
 3876 Mikael Ronstrom	2012-04-05
      Bug fixes of LOCK_open, lock where unlock should have been made, wrong order of locking table cache mutexes and LOCK_open, could lead to deadlock

    modified:
      sql/sql_base.cc
 3875 Mikael Ronstrom	2012-04-02
      More comments on split of mutex protection in WL#5772

    modified:
      sql/sql_base.cc
=== modified file 'sql/sql_base.cc'
--- a/sql/sql_base.cc	revid:mikael.ronstrom@stripped
+++ b/sql/sql_base.cc	revid:mikael.ronstrom@stripped
@@ -158,10 +158,6 @@ Repair_mrg_table_error_handler::handle_c
 */
 
 /**
-  Protects table_def_hash, used and unused lists in the
-  TABLE_SHARE object, LRU lists of used TABLEs and used
-  TABLE_SHAREs, refresh_version and the table id counter.
-  RONM TODO: Update what LOCK_open is used for
   LOCK_open protects the following variables:
   1) The table_def_cache
     This is the hash table mapping table name to a table
@@ -1249,6 +1245,7 @@ bool TABLE_SHARE::visit_subgraph(Wait_fo
   TABLE *table;
   MDL_context *src_ctx= wait_for_flush->get_ctx();
   bool result= TRUE;
+  bool locked= FALSE;
   uint i;
 
   /*
@@ -1260,6 +1257,7 @@ bool TABLE_SHARE::visit_subgraph(Wait_fo
   */
   if (gvisitor->m_lock_open_count++ == 0)
   {
+    locked= TRUE;
     lock_all_table_caches();
     mysql_mutex_lock(&LOCK_open);
   }
@@ -1313,10 +1311,12 @@ end_leave_node:
   gvisitor->leave_node(src_ctx);
 
 end:
-  if (gvisitor->m_lock_open_count-- == 1)
+  gvisitor->m_lock_open_count--;
+  if (locked)
   {
-    unlock_all_table_caches();
+    assert(gvisitor->m_lock_open_count == 0);
     mysql_mutex_unlock(&LOCK_open);
+    unlock_all_table_caches();
   }
 
   return result;
@@ -2012,7 +2012,7 @@ bool close_thread_table(THD *thd, TABLE 
     {
       mysql_mutex_lock(&LOCK_open);
       free_cache_entry(tc, tc->unused_tables);
-      mysql_mutex_lock(&LOCK_open);
+      mysql_mutex_unlock(&LOCK_open);
     }
   }
   unlock_table_cache(thd->thread_id);
@@ -9657,8 +9657,8 @@ void tdc_remove_table(THD *thd, enum_tdc
 
   if (! has_lock)
   {
-    mysql_mutex_lock(&LOCK_open);
     lock_all_table_caches();
+    mysql_mutex_lock(&LOCK_open);
   }
   else
   {

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