On Wed, 2012-04-25 at 13:30 -0400, J. Bruce Fields wrote: > On Fri, Apr 20, 2012 at 06:11:02PM +0400, Stanislav Kinsbursky wrote: > > v2: atomic_inc_return() was replaced by atomic_inc_not_zero(). > > > > These clients can't be safely dereferenced if their counter in 0. > > I'm pretty confused by how these notifiers work.... > > rpc_release_client decrements cl_count to zero temporarily, to have it > immediately re-incremented by rpc_free_auth. > > So if we're called concurrently with rpc_release_client then it's sort > of random whether someone gets this callback. > > Is that a problem? Not really. If we re-increment the client->cl_count in rpc_free_auth() then it would be so that we can send off a bunch of NULL rpc calls to destroy existing RPCSEC_GSS contexts. We shouldn't need to do any more upcalls in pipefs. If we care, we could simply move the call to rpc_unregister_client() into rpc_free_auth() so that the pipefs notifier doesn't see us, or we could set a flag to have it ignore us. > Also, is this an existing bug? (In which case Trond should take it > now.) -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com ��.n��������+%������w��{.n�����{��w���jg��������ݢj����G�������j:+v���w�m������w�������h�����٥