From: Jeff Layton Subject: [PATCH 3/3] lockd: close potential race with rapid lockd_up/lockd_down cycle Date: Wed, 11 Jun 2008 10:03:12 -0400 Message-ID: <1213192992-7635-4-git-send-email-jlayton@redhat.com> References: <1213192992-7635-1-git-send-email-jlayton@redhat.com> <1213192992-7635-2-git-send-email-jlayton@redhat.com> <1213192992-7635-3-git-send-email-jlayton@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: linux-nfs@vger.kernel.org, nfsv4@linux-nfs.org, linux-kernel@vger.kernel.org To: trond.myklebust@fys.uio.no, bfields@fieldses.org Return-path: In-Reply-To: <1213192992-7635-3-git-send-email-jlayton@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfsv4-bounces@linux-nfs.org Errors-To: nfsv4-bounces@linux-nfs.org List-ID: If lockd_down is called very rapidly after lockd_up returns, then there is a slim chance that lockd() will never be called. kthread() will return before calling the function, so we'll end up never actually calling the cleanup functions for the thread. Signed-off-by: Jeff Layton --- fs/lockd/svc.c | 33 +++++++++++++-------------------- 1 files changed, 13 insertions(+), 20 deletions(-) diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 2169af4..5bd9bf0 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -50,7 +50,7 @@ EXPORT_SYMBOL(nlmsvc_ops); static DEFINE_MUTEX(nlmsvc_mutex); static unsigned int nlmsvc_users; static struct task_struct *nlmsvc_task; -static struct svc_serv *nlmsvc_serv; +static struct svc_rqst *nlmsvc_rqst; int nlmsvc_grace_period; unsigned long nlmsvc_timeout; @@ -194,20 +194,11 @@ lockd(void *vrqstp) svc_process(rqstp); } - flush_signals(current); if (nlmsvc_ops) nlmsvc_invalidate_all(); nlm_shutdown_hosts(); - unlock_kernel(); - - nlmsvc_task = NULL; - nlmsvc_serv = NULL; - - /* Exit the RPC thread */ - svc_exit_thread(rqstp); - return 0; } @@ -254,16 +245,15 @@ int lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */ { struct svc_serv *serv; - struct svc_rqst *rqstp; int error = 0; mutex_lock(&nlmsvc_mutex); /* * Check whether we're already up and running. */ - if (nlmsvc_serv) { + if (nlmsvc_rqst) { if (proto) - error = make_socks(nlmsvc_serv, proto); + error = make_socks(nlmsvc_rqst->rq_server, proto); goto out; } @@ -288,9 +278,10 @@ lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */ /* * Create the kernel thread and wait for it to start. */ - rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]); - if (IS_ERR(rqstp)) { - error = PTR_ERR(rqstp); + nlmsvc_rqst = svc_prepare_thread(serv, &serv->sv_pools[0]); + if (IS_ERR(nlmsvc_rqst)) { + error = PTR_ERR(nlmsvc_rqst); + nlmsvc_rqst = NULL; printk(KERN_WARNING "lockd_up: svc_rqst allocation failed, error=%d\n", error); @@ -298,16 +289,15 @@ lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */ } svc_sock_update_bufs(serv); - nlmsvc_serv = rqstp->rq_server; - nlmsvc_task = kthread_run(lockd, rqstp, serv->sv_name); + nlmsvc_task = kthread_run(lockd, nlmsvc_rqst, serv->sv_name); if (IS_ERR(nlmsvc_task)) { error = PTR_ERR(nlmsvc_task); + svc_exit_thread(nlmsvc_rqst); nlmsvc_task = NULL; - nlmsvc_serv = NULL; + nlmsvc_rqst = NULL; printk(KERN_WARNING "lockd_up: kthread_run failed, error=%d\n", error); - svc_exit_thread(rqstp); goto destroy_and_out; } @@ -346,6 +336,9 @@ lockd_down(void) BUG(); } kthread_stop(nlmsvc_task); + svc_exit_thread(nlmsvc_rqst); + nlmsvc_task = NULL; + nlmsvc_rqst = NULL; out: mutex_unlock(&nlmsvc_mutex); } -- 1.5.3.6