postreview fixes

sql/item_func.cc:
  some optimisation
sql/sql_acl.cc:
  some optimisation
sql/sql_base.cc:
  some optimisation
sql/sql_parse.cc:
  some optimisation
sql/table.cc:
  some optimisation

sql/item_func.cc

@@ -4756,13 +4756,12 @@ Item_func_sp::execute(Item **itp)
   THD *thd= current_thd;
   int res= -1;
   Sub_statement_state statement_state;
-  Security_context *save_security_ctx= 0, *save_ctx_func;
+  Security_context *save_security_ctx= thd->security_ctx, *save_ctx_func;
 
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
   if (context->security_ctx)
   {
     /* Set view definer security context */
-    save_security_ctx= thd->security_ctx;
     thd->security_ctx= context->security_ctx;
   }
 #endif
@@ -4787,7 +4786,6 @@ Item_func_sp::execute(Item **itp)
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
   sp_restore_security_context(thd, save_ctx_func);
 error:
-  if (save_security_ctx)
   thd->security_ctx= save_security_ctx;
 #else
 error:

sql/sql_acl.cc

@@ -3532,7 +3532,7 @@ bool check_grant(THD *thd, ulong want_access, TABLE_LIST *tables,
     of other queries). For simple queries first_not_own_table is 0.
   */
   for (i= 0, table= tables;
-       table && table != first_not_own_table && i < number;
+       table != first_not_own_table && i < number;
        table= table->next_global, i++)
   {
     /* Remove SHOW_VIEW_ACL, because it will be checked during making view */

sql/sql_base.cc

@@ -2705,15 +2705,13 @@ static bool check_grant_column_in_sctx(THD *thd, GRANT_INFO *grant,
 {
   if (!check_grants)
     return FALSE;
-  Security_context *save_security_ctx= 0;
+  Security_context *save_security_ctx= thd->security_ctx;
   bool res;
   if (sctx)
   {
-    save_security_ctx= thd->security_ctx;
     thd->security_ctx= sctx;
   }
   res= check_grant_column(thd, grant, db, table, name, length);
-  if (save_security_ctx)
   thd->security_ctx= save_security_ctx;
   return res;
 }

sql/sql_parse.cc

@@ -5033,7 +5033,7 @@ check_table_access(THD *thd, ulong want_access,TABLE_LIST *tables,
     the given table list refers to the list for prelocking (contains tables
     of other queries). For simple queries first_not_own_table is 0.
   */
-  for (; tables && tables != first_not_own_table; tables= tables->next_global)
+  for (; tables != first_not_own_table; tables= tables->next_global)
   {
     if (tables->schema_table && 
         (want_access & ~(SELECT_ACL | EXTRA_ACL | FILE_ACL)))

sql/table.cc

@@ -2654,7 +2654,7 @@ Natural_join_column::check_grants(THD *thd, const char *name, uint length)
   GRANT_INFO *grant;
   const char *db_name;
   const char *table_name;
-  Security_context *save_security_ctx= 0;
+  Security_context *save_security_ctx= thd->security_ctx;
   Security_context *new_sctx= table_ref->security_ctx;
   bool res;
 
@@ -2675,11 +2675,9 @@ Natural_join_column::check_grants(THD *thd, const char *name, uint length)
 
   if (new_sctx)
   {
-    save_security_ctx= thd->security_ctx;
     thd->security_ctx= new_sctx;
   }
   res= check_grant_column(thd, grant, db_name, table_name, name, length);
-  if (save_security_ctx)
   thd->security_ctx= save_security_ctx;
   return res;
 }