From patchwork Tue Jul 16 22:53:56 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 259556 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id B8F6F2C00CA for ; Wed, 17 Jul 2013 09:12:49 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzEQF-0003C2-AR; Tue, 16 Jul 2013 23:12:43 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzE89-0000Nx-Ie for kernel-team@lists.ubuntu.com; Tue, 16 Jul 2013 22:54:01 +0000 Received: from c-67-160-231-162.hsd1.ca.comcast.net ([67.160.231.162] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UzE86-00043R-NH; Tue, 16 Jul 2013 22:53:58 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1UzE84-00074Z-O6; Tue, 16 Jul 2013 15:53:56 -0700 From: Kamal Mostafa To: Stanislav Kinsbursky Subject: [ 3.8.y.z extended stable ] Patch "SUNRPC: fix races on PipeFS UMOUNT notifications" has been added to staging queue Date: Tue, 16 Jul 2013 15:53:56 -0700 Message-Id: <1374015236-27153-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 X-Extended-Stable: 3.8 Cc: Kamal Mostafa , Trond Myklebust , kernel-team@lists.ubuntu.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled SUNRPC: fix races on PipeFS UMOUNT notifications to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.5. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 26655857295527252a3d6606b4cb248580b7843d Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Wed, 26 Jun 2013 10:15:14 +0400 Subject: SUNRPC: fix races on PipeFS UMOUNT notifications commit adb6fa7ffe9031857ec14b8aab75c9ab65556cbc upstream. CPU#0 CPU#1 ----------------------------- ----------------------------- rpc_kill_sb sn->pipefs_sb = NULL rpc_release_client (UMOUNT_EVENT) rpc_free_auth rpc_pipefs_event rpc_get_client_for_event !atomic_inc_not_zero(cl_count) atomic_inc(cl_count) rpc_free_client rpc_clnt_remove_pipedir To fix this, this patch does the following: 1) Calls RPC_PIPEFS_UMOUNT notification with sn->pipefs_sb_lock being held. 2) Removes SUNRPC client from the list AFTER pipes destroying. 3) Doesn't hold RPC client on notification: if client in the list, then it can't be destroyed while sn->pipefs_sb_lock in hold by notification caller. Signed-off-by: Stanislav Kinsbursky Signed-off-by: Trond Myklebust Signed-off-by: Kamal Mostafa --- net/sunrpc/clnt.c | 5 +---- net/sunrpc/rpc_pipe.c | 2 +- 2 files changed, 2 insertions(+), 5 deletions(-) -- 1.8.1.2 diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index f87fe8e..a4207ae 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -235,8 +235,6 @@ static struct rpc_clnt *rpc_get_client_for_event(struct net *net, int event) continue; if (rpc_clnt_skip_event(clnt, event)) continue; - if (atomic_inc_not_zero(&clnt->cl_count) == 0) - continue; spin_unlock(&sn->rpc_client_lock); return clnt; } @@ -253,7 +251,6 @@ static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event, while ((clnt = rpc_get_client_for_event(sb->s_fs_info, event))) { error = __rpc_pipefs_event(clnt, event, sb); - rpc_release_client(clnt); if (error) break; } @@ -639,8 +636,8 @@ rpc_free_client(struct rpc_clnt *clnt) rcu_dereference(clnt->cl_xprt)->servername); if (clnt->cl_parent != clnt) rpc_release_client(clnt->cl_parent); - rpc_unregister_client(clnt); rpc_clnt_remove_pipedir(clnt); + rpc_unregister_client(clnt); rpc_free_iostats(clnt->cl_metrics); kfree(clnt->cl_principal); clnt->cl_metrics = NULL; diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 6af77d1..87a616a 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -1160,12 +1160,12 @@ static void rpc_kill_sb(struct super_block *sb) goto out; } sn->pipefs_sb = NULL; - mutex_unlock(&sn->pipefs_sb_lock); dprintk("RPC: sending pipefs UMOUNT notification for net %p%s\n", net, NET_NAME(net)); blocking_notifier_call_chain(&rpc_pipefs_notifier_list, RPC_PIPEFS_UMOUNT, sb); + mutex_unlock(&sn->pipefs_sb_lock); put_net(net); out: kill_litter_super(sb);