Hi Sergei, On Thu, May 07, 2015 at 01:04:24PM +0200, Sergei Golubchik wrote: > Hi, Sergey! > > On Mar 17, [email protected] wrote: > > revision-id: 93e746afb2d1a23cb933291ad736a20858b5ac3e > > parent(s): ccc7297fe94af1129c717f91d31fa075d54a0371 > > committer: Sergey Vojtovich > > branch nick: mariadb > > timestamp: 2015-03-17 19:49:04 +0400 > > message: > > > > MDEV-7793 - Race condition between XA COMMIT/ROLLBACK and disconnect > > > > XA COMMIT/ROLLBACK of XA transaction owned by different thread may access > > freed memory if that thread disconnects at the same time. > > > > Also concurrent XA COMMIT/ROLLBACK of recovered XA transaction were not > > serialized properly. > > > > diff --git a/sql/sql_class.cc b/sql/sql_class.cc > > index 3071ba6..f18231d 100644 > > --- a/sql/sql_class.cc > > +++ b/sql/sql_class.cc > > @@ -5355,7 +5378,7 @@ bool xid_cache_insert(THD *thd, XID_STATE *xid_state) > > switch (res) > > { > > case 0: > > - xid_state->xid_cache_element->mark_initialized(); > > + xid_state->xid_cache_element->set(XID_cache_element::ACQUIRED); > > Why not mark_acquired() here? mark_acquired() is intended to acquire RECOVERED elements. That is to allow multiple threads to attempt to acquire the same XID. One thread will succeed, others will get "not found".
> Can you be sure that no other thread has already acquired this > xid_cache_element after you've inserted it? Only RECOVERED elements can be acquired. This newly inserted element has m_state == 0. Thanks, Sergey _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
