Bug#10224 - ANALYZE TABLE crashing with simultaneous CREATE ... SELECT statement.

1.) Added a new option to mysql_lock_tables() for ignoring FLUSH TABLES.
Used the new option in create_table_from_items().
It is necessary to prevent the SELECT table from being reopend.
It would get new storage assigned for its fields, while the
SELECT part of the command would still use the old (freed) storage.
2.) Protected the CREATE TABLE and CREATE TABLE ... SELECT commands
against a global read lock. This prevents a deadlock in
CREATE TABLE ... SELECT in conjunction with FLUSH TABLES WITH READ LOCK
and avoids the creation of new tables during a global read lock.
3.) Replaced set_protect_against_global_read_lock() and
unset_protect_against_global_read_lock() by
wait_if_global_read_lock() and start_waiting_global_read_lock()
in the INSERT DELAYED handling.

mysql-test/r/create.result

@@ -228,3 +228,11 @@ create table t1 (a int,,b int);
 You have an error in your SQL syntax.  Check the manual that corresponds to your MySQL server version for the right syntax to use near 'b int)' at line 1
 create table t1 (,b int);
 You have an error in your SQL syntax.  Check the manual that corresponds to your MySQL server version for the right syntax to use near 'b int)' at line 1
+create table t1 (a int);
+create table t1 select * from t1;
+INSERT TABLE 't1' isn't allowed in FROM table list
+create table t2 union = (t1) select * from t1;
+INSERT TABLE 't1' isn't allowed in FROM table list
+flush tables with read lock;
+unlock tables;
+drop table t1;

mysql-test/t/create.test

@@ -203,3 +203,18 @@ create table t1 (a int,);
 create table t1 (a int,,b int);
 --error 1064
 create table t1 (,b int);
+
+#
+# Bug#10224 - ANALYZE TABLE crashing with simultaneous
+# CREATE ... SELECT statement.
+# This tests two additional possible errors and a hang if 
+# an improper fix is present.
+#
+create table t1 (a int);
+--error 1093
+create table t1 select * from t1;
+--error 1093
+create table t2 union = (t1) select * from t1;
+flush tables with read lock;
+unlock tables;
+drop table t1;

sql/lock.cc

@@ -79,8 +79,24 @@ static int unlock_external(THD *thd, TABLE **table,uint count);
 static void print_lock_error(int error);
 
 
-MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
-                              bool ignore_global_read_lock)
+/*
+  Lock tables.
+
+  SYNOPSIS
+    mysql_lock_tables()
+    thd                         The current thread.
+    tables                      An array of pointers to the tables to lock.
+    count                       The number of tables to lock.
+    flags                       Options:
+      MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK      Ignore a global read lock
+      MYSQL_LOCK_IGNORE_FLUSH                 Ignore a flush tables.
+
+  RETURN
+    A lock structure pointer on success.
+    NULL on error.
+*/
+
+MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count, uint flags)
 {
   MYSQL_LOCK *sql_lock;
   TABLE *write_lock_used;
@@ -91,7 +107,8 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
     if (!(sql_lock = get_lock_data(thd,tables,count, 0,&write_lock_used)))
       break;
 
-    if (global_read_lock && write_lock_used && ! ignore_global_read_lock)
+    if (global_read_lock && write_lock_used &&
+        ! (flags & MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK))
     {
       /*
 	Someone has issued LOCK ALL TABLES FOR READ and we want a write lock
@@ -125,7 +142,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **tables, uint count,
       thd->some_tables_deleted=1;		// Try again
       sql_lock->lock_count=0;			// Locks are alread freed
     }
-    else if (!thd->some_tables_deleted)
+    else if (!thd->some_tables_deleted || (flags & MYSQL_LOCK_IGNORE_FLUSH))
     {
       thd->locked=0;
       break;
@@ -868,47 +885,3 @@ void make_global_read_lock_block_commit(THD *thd)
 }
 
 
-/*
-  Set protection against global read lock.
-
-  SYNOPSIS
-    set_protect_against_global_read_lock()
-    void
-
-  RETURN
-    FALSE       OK, no global read lock exists.
-    TRUE        Error, global read lock exists already.
-*/
-
-my_bool set_protect_against_global_read_lock(void)
-{
-  my_bool       global_read_lock_exists;
-
-  pthread_mutex_lock(&LOCK_open);
-  if (! (global_read_lock_exists= test(global_read_lock)))
-    protect_against_global_read_lock++;
-  pthread_mutex_unlock(&LOCK_open);
-  return global_read_lock_exists;
-}
-
-
-/*
-  Unset protection against global read lock.
-
-  SYNOPSIS
-    unset_protect_against_global_read_lock()
-    void
-
-  RETURN
-    void
-*/
-
-void unset_protect_against_global_read_lock(void)
-{
-  pthread_mutex_lock(&LOCK_open);
-  protect_against_global_read_lock--;
-  pthread_mutex_unlock(&LOCK_open);
-  pthread_cond_broadcast(&COND_refresh);
-}
-
-

sql/mysql_priv.h

@@ -766,8 +766,11 @@ extern pthread_t signal_thread;
 extern struct st_VioSSLAcceptorFd * ssl_acceptor_fd;
 #endif /* HAVE_OPENSSL */
 
-MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count,
-                              bool ignore_global_read_lock= FALSE);
+MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count, uint flags);
+/* mysql_lock_tables() flags bits */
+#define MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK      0x0001
+#define MYSQL_LOCK_IGNORE_FLUSH                 0x0002
+
 void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock);
 void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock);
 void mysql_unlock_some_tables(THD *thd, TABLE **table,uint count);

sql/sql_acl.cc

@@ -177,7 +177,7 @@ my_bool acl_init(THD *org_thd, bool dont_read_acl_tables)
   ptr[0]= tables[0].table;
   ptr[1]= tables[1].table;
   ptr[2]= tables[2].table;
-  if (!(lock=mysql_lock_tables(thd,ptr,3)))
+  if (! (lock= mysql_lock_tables(thd, ptr, 3, 0)))
   {
     sql_print_error("Fatal error: Can't lock privilege tables: %s",
 		    thd->net.last_error);
@@ -2514,7 +2514,7 @@ my_bool grant_init(THD *org_thd)
   TABLE *ptr[2];				// Lock tables for quick update
   ptr[0]= tables[0].table;
   ptr[1]= tables[1].table;
-  if (!(lock=mysql_lock_tables(thd,ptr,2)))
+  if (! (lock= mysql_lock_tables(thd, ptr, 2, 0)))
     goto end;
 
   t_table = tables[0].table; c_table = tables[1].table;

sql/sql_base.cc

@@ -1161,7 +1161,7 @@ bool reopen_tables(THD *thd,bool get_locks,bool in_refresh)
     MYSQL_LOCK *lock;
     /* We should always get these locks */
     thd->some_tables_deleted=0;
-    if ((lock=mysql_lock_tables(thd,tables,(uint) (tables_ptr-tables))))
+    if ((lock= mysql_lock_tables(thd, tables, (uint) (tables_ptr-tables), 0)))
     {
       thd->locked_tables=mysql_lock_merge(thd->locked_tables,lock);
     }
@@ -1602,7 +1602,7 @@ TABLE *open_ltable(THD *thd, TABLE_LIST *table_list, thr_lock_type lock_type)
     else
     {
       if ((table->reginfo.lock_type= lock_type) != TL_UNLOCK)
-	if (!(thd->lock=mysql_lock_tables(thd,&table_list->table,1)))
+	if (! (thd->lock= mysql_lock_tables(thd, &table_list->table, 1, 0)))
 	  table= 0;
     }
   }
@@ -1653,7 +1653,7 @@ int lock_tables(THD *thd,TABLE_LIST *tables)
       return -1;
     for (table = tables ; table ; table=table->next)
       *(ptr++)= table->table;
-    if (!(thd->lock=mysql_lock_tables(thd,start,count)))
+    if (! (thd->lock= mysql_lock_tables(thd, start, count, 0)))
       return -1;				/* purecov: inspected */
   }
   else

sql/sql_handler.cc

@@ -448,7 +448,7 @@ int mysql_ha_read(THD *thd, TABLE_LIST *tables,
   send_fields(thd,list,1);
 
   HANDLER_TABLES_HACK(thd);
-  lock= mysql_lock_tables(thd, &tables->table, 1);
+  lock= mysql_lock_tables(thd, &tables->table, 1, 0);
   HANDLER_TABLES_HACK(thd);
   
   byte *key;

sql/sql_insert.cc

@@ -674,10 +674,13 @@ static TABLE *delayed_get_table(THD *thd,TABLE_LIST *table_list)
         Avoid that a global read lock steps in while we are creating the
         new thread. It would block trying to open the table. Hence, the
         DI thread and this thread would wait until after the global
-        readlock is gone. If the read lock exists already, we leave with
-        no table and then switch to non-delayed insert.
+        readlock is gone. Since the insert thread needs to wait for a
+        global read lock anyway, we do it right now. Note that
+        wait_if_global_read_lock() sets a protection against a new
+        global read lock when it succeeds. This needs to be released by
+        start_waiting_global_read_lock().
       */
-      if (set_protect_against_global_read_lock())
+      if (wait_if_global_read_lock(thd, 0, 1))
         goto err;
       if (!(tmp=new delayed_insert()))
       {
@@ -719,7 +722,11 @@ static TABLE *delayed_get_table(THD *thd,TABLE_LIST *table_list)
 	pthread_cond_wait(&tmp->cond_client,&tmp->mutex);
       }
       pthread_mutex_unlock(&tmp->mutex);
-      unset_protect_against_global_read_lock();
+      /*
+        Release the protection against the global read lock and wake
+        everyone, who might want to set a global read lock.
+      */
+      start_waiting_global_read_lock(thd);
       thd->proc_info="got old table";
       if (tmp->thd.killed)
       {
@@ -755,7 +762,11 @@ static TABLE *delayed_get_table(THD *thd,TABLE_LIST *table_list)
 
  err1:
   thd->fatal_error= 1;
-  unset_protect_against_global_read_lock();
+  /*
+    Release the protection against the global read lock and wake
+    everyone, who might want to set a global read lock.
+  */
+  start_waiting_global_read_lock(thd);
  err:
   pthread_mutex_unlock(&LOCK_delayed_create);
   DBUG_RETURN(0); // Continue with normal insert
@@ -1105,7 +1116,8 @@ extern "C" pthread_handler_decl(handle_delayed_insert,arg)
         handler will close the table and finish when the outstanding
         inserts are done.
       */
-      if (! (thd->lock= mysql_lock_tables(thd, &di->table, 1, TRUE)))
+      if (! (thd->lock= mysql_lock_tables(thd, &di->table, 1,
+                                          MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK)))
       {
 	di->dead=thd->killed=1;			// Fatal error
       }

sql/sql_parse.cc

@@ -1673,6 +1673,24 @@ mysql_execute_command(void)
       break;
     }
 #endif
+    /*
+      The create-select command will open and read-lock the select table
+      and then create, open and write-lock the new table. If a global
+      read lock steps in, we get a deadlock. The write lock waits for
+      the global read lock, while the global read lock waits for the
+      select table to be closed. So we wait until the global readlock is
+      gone before starting both steps. Note that
+      wait_if_global_read_lock() sets a protection against a new global
+      read lock when it succeeds. This needs to be released by
+      start_waiting_global_read_lock(). We protect the normal CREATE
+      TABLE in the same way. That way we avoid that a new table is
+      created during a gobal read lock.
+    */
+    if (wait_if_global_read_lock(thd, 0, 1))
+    {
+      res= -1;
+      break;
+    }
     if (select_lex->item_list.elements)		// With select
     {
       select_result *result;
@@ -1681,7 +1699,7 @@ mysql_execute_command(void)
 	  check_dup(tables->db, tables->real_name, tables->next))
       {
 	net_printf(&thd->net,ER_INSERT_TABLE_USED,tables->real_name);
-	DBUG_VOID_RETURN;
+	goto error1;
       }
       if (lex->create_info.used_fields & HA_CREATE_USED_UNION)
       {
@@ -1692,7 +1710,7 @@ mysql_execute_command(void)
                         (TABLE_LIST*)lex->create_info.merge_list.first))
           {
             net_printf(&thd->net, ER_INSERT_TABLE_USED, tab->real_name);
-            DBUG_VOID_RETURN;
+            goto error1;
           }
         }  
       }    
@@ -1700,7 +1718,7 @@ mysql_execute_command(void)
       {
 	TABLE_LIST *table;
 	if (check_table_access(thd, SELECT_ACL, tables->next))
-	  goto error;				// Error message is given
+          goto error1;				// Error message is given
 	/* TODO: Delete the following loop when locks is set by sql_yacc */
 	for (table = tables->next ; table ; table=table->next)
 	  table->lock_type= lex->lock_option;
@@ -1737,6 +1755,11 @@ mysql_execute_command(void)
       if (!res)
 	send_ok(&thd->net);
     }
+    /*
+      Release the protection against the global read lock and wake
+      everyone, who might want to set a global read lock.
+    */
+    start_waiting_global_read_lock(thd);
     break;
   }
   case SQLCOM_CREATE_INDEX:
@@ -2674,6 +2697,14 @@ error:
       thd->lock= 0;
   }
   DBUG_VOID_RETURN;
+
+ error1:
+  /*
+    Release the protection against the global read lock and wake
+    everyone, who might want to set a global read lock.
+  */
+  start_waiting_global_read_lock(thd);
+  DBUG_VOID_RETURN;
 }
 
 

sql/sql_table.cc

@@ -896,7 +896,7 @@ TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info,
   if (!table)
     DBUG_RETURN(0);
   table->reginfo.lock_type=TL_WRITE;
-  if (!((*lock)=mysql_lock_tables(thd,&table,1)))
+  if (! ((*lock)= mysql_lock_tables(thd, &table, 1, MYSQL_LOCK_IGNORE_FLUSH)))
   {
     VOID(pthread_mutex_lock(&LOCK_open));
     hash_delete(&open_cache,(byte*) table);