From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from relay.parallels.com ([195.214.232.42]:39906 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759972Ab2D0OIU (ORCPT ); Fri, 27 Apr 2012 10:08:20 -0400 Message-ID: <4F9AA84D.8090604@parallels.com> Date: Fri, 27 Apr 2012 18:08:13 +0400 From: Stanislav Kinsbursky MIME-Version: 1.0 To: "J. Bruce Fields" CC: "Trond.Myklebust@netapp.com" , "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@openvz.org" Subject: Re: [PATCH 2/3] SUNRPC: check rpcbind clients usage counter before decrement References: <20120425132314.13800.6813.stgit@localhost6.localdomain6> <20120425133749.13800.24003.stgit@localhost6.localdomain6> <20120427135507.GE14973@fieldses.org> In-Reply-To: <20120427135507.GE14973@fieldses.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 27.04.2012 17:55, J. Bruce Fields wrote: > On Wed, Apr 25, 2012 at 05:37:49PM +0400, Stanislav Kinsbursky wrote: >> Registering service with svc_bind() can fail. In this case service will be >> destroyed and during destruction it will try to unregister itself from rpcbind. >> In this case unregister have to be skipped. > > Isn't this a preexisting bug, in which case perhaps Trond should at it > to his list of bugs to submit now? > Not it's not. Previously, in case of bind operations failure, rpcb_put_local() wasn't called, but service data was destroyed instead: - if (svc_uses_rpcbind(serv)) { - if (svc_rpcb_setup(serv, current->nsproxy->net_ns) < 0) { - kfree(serv->sv_pools); - kfree(serv); - return NULL; - } - if (!serv->sv_shutdown) - serv->sv_shutdown = svc_rpcb_cleanup; - } Now (with svc_bind() introduction) service can be created, but svc_bind() could fail. And thus svc_destroy() have to be called. Which will call rpcb_put_local(). And the problem here that svc_bind() can fail before incrementing of rpcb usage counter. > --b. > >> >> Signed-off-by: Stanislav Kinsbursky >> >> --- >> net/sunrpc/rpcb_clnt.c | 12 +++++++----- >> 1 files changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c >> index 78ac39f..4c38b33 100644 >> --- a/net/sunrpc/rpcb_clnt.c >> +++ b/net/sunrpc/rpcb_clnt.c >> @@ -180,14 +180,16 @@ void rpcb_put_local(struct net *net) >> struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); >> struct rpc_clnt *clnt = sn->rpcb_local_clnt; >> struct rpc_clnt *clnt4 = sn->rpcb_local_clnt4; >> - int shutdown; >> + int shutdown = 0; >> >> spin_lock(&sn->rpcb_clnt_lock); >> - if (--sn->rpcb_users == 0) { >> - sn->rpcb_local_clnt = NULL; >> - sn->rpcb_local_clnt4 = NULL; >> + if (sn->rpcb_users) { >> + if (--sn->rpcb_users == 0) { >> + sn->rpcb_local_clnt = NULL; >> + sn->rpcb_local_clnt4 = NULL; >> + } >> + shutdown = !sn->rpcb_users; >> } >> - shutdown = !sn->rpcb_users; >> spin_unlock(&sn->rpcb_clnt_lock); >> >> if (shutdown) { >> -- Best regards, Stanislav Kinsbursky