From patchwork Wed Jan 16 10:34:00 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 212480 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 5CD992C0094 for ; Wed, 16 Jan 2013 21:43:51 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759055Ab3APKmf (ORCPT ); Wed, 16 Jan 2013 05:42:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45547 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759035Ab3APKmd (ORCPT ); Wed, 16 Jan 2013 05:42:33 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r0GAgWhg022406 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 16 Jan 2013 05:42:33 -0500 Received: from amd-6168-8-1.englab.nay.redhat.com (amd-6168-8-1.englab.nay.redhat.com [10.66.104.52]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r0GAgOVT006005; Wed, 16 Jan 2013 05:42:30 -0500 From: Jason Wang To: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jason Wang Subject: [PATCH V5 2/3] vhost_net: handle polling errors when setting backend Date: Wed, 16 Jan 2013 18:34:00 +0800 Message-Id: <1358332441-26859-3-git-send-email-jasowang@redhat.com> In-Reply-To: <1358332441-26859-1-git-send-email-jasowang@redhat.com> References: <1358332441-26859-1-git-send-email-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, the polling errors were ignored, which can lead following issues: - vhost remove itself unconditionally from waitqueue when stopping the poll, this may crash the kernel since the previous attempt of starting may fail to add itself to the waitqueue - userspace may think the backend were successfully set even when the polling failed. Solve this by: - check poll->wqh before trying to remove from waitqueue - report polling errors in vhost_poll_start(), tx_poll_start(), the return value will be checked and returned when userspace want to set the backend After this fix, there still could be a polling failure after backend is set, it will addressed by the next patch. Signed-off-by: Jason Wang --- drivers/vhost/net.c | 27 ++++++++++++++++++--------- drivers/vhost/vhost.c | 18 +++++++++++++++--- drivers/vhost/vhost.h | 2 +- 3 files changed, 34 insertions(+), 13 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index d10ad6f..959b1cd 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -165,12 +165,16 @@ static void tx_poll_stop(struct vhost_net *net) } /* Caller must have TX VQ lock */ -static void tx_poll_start(struct vhost_net *net, struct socket *sock) +static int tx_poll_start(struct vhost_net *net, struct socket *sock) { + int ret; + if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED)) - return; - vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file); - net->tx_poll_state = VHOST_NET_POLL_STARTED; + return 0; + ret = vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file); + if (!ret) + net->tx_poll_state = VHOST_NET_POLL_STARTED; + return ret; } /* In case of DMA done not in order in lower device driver for some reason. @@ -642,20 +646,23 @@ static void vhost_net_disable_vq(struct vhost_net *n, vhost_poll_stop(n->poll + VHOST_NET_VQ_RX); } -static void vhost_net_enable_vq(struct vhost_net *n, +static int vhost_net_enable_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { struct socket *sock; + int ret; sock = rcu_dereference_protected(vq->private_data, lockdep_is_held(&vq->mutex)); if (!sock) - return; + return 0; if (vq == n->vqs + VHOST_NET_VQ_TX) { n->tx_poll_state = VHOST_NET_POLL_STOPPED; - tx_poll_start(n, sock); + ret = tx_poll_start(n, sock); } else - vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file); + ret = vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file); + + return ret; } static struct socket *vhost_net_stop_vq(struct vhost_net *n, @@ -833,7 +840,9 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) r = vhost_init_used(vq); if (r) goto err_used; - vhost_net_enable_vq(n, vq); + r = vhost_net_enable_vq(n, vq); + if (r) + goto err_used; oldubufs = vq->ubufs; vq->ubufs = ubufs; diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 34389f7..9759249 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -77,26 +77,38 @@ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, init_poll_funcptr(&poll->table, vhost_poll_func); poll->mask = mask; poll->dev = dev; + poll->wqh = NULL; vhost_work_init(&poll->work, fn); } /* Start polling a file. We add ourselves to file's wait queue. The caller must * keep a reference to a file until after vhost_poll_stop is called. */ -void vhost_poll_start(struct vhost_poll *poll, struct file *file) +int vhost_poll_start(struct vhost_poll *poll, struct file *file) { unsigned long mask; + int ret = 0; mask = file->f_op->poll(file, &poll->table); if (mask) vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); + if (mask & POLLERR) { + if (poll->wqh) + remove_wait_queue(poll->wqh, &poll->wait); + ret = -EINVAL; + } + + return ret; } /* Stop polling a file. After this function returns, it becomes safe to drop the * file reference. You must also flush afterwards. */ void vhost_poll_stop(struct vhost_poll *poll) { - remove_wait_queue(poll->wqh, &poll->wait); + if (poll->wqh) { + remove_wait_queue(poll->wqh, &poll->wait); + poll->wqh = NULL; + } } static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, @@ -792,7 +804,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) fput(filep); if (pollstart && vq->handle_kick) - vhost_poll_start(&vq->poll, vq->kick); + r = vhost_poll_start(&vq->poll, vq->kick); mutex_unlock(&vq->mutex); diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 2639c58..17261e2 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -42,7 +42,7 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work); void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, unsigned long mask, struct vhost_dev *dev); -void vhost_poll_start(struct vhost_poll *poll, struct file *file); +int vhost_poll_start(struct vhost_poll *poll, struct file *file); void vhost_poll_stop(struct vhost_poll *poll); void vhost_poll_flush(struct vhost_poll *poll); void vhost_poll_queue(struct vhost_poll *poll);