From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net-next v6 1/4] net: vhost: lock the vqs one by one Date: Sun, 22 Jul 2018 18:26:26 +0300 Message-ID: <20180722182448-mutt-send-email-mst@kernel.org> References: <1532196242-2998-1-git-send-email-xiangxia.m.yue@gmail.com> <1532196242-2998-2-git-send-email-xiangxia.m.yue@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jasowang@redhat.com, makita.toshiaki@lab.ntt.co.jp, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org To: xiangxia.m.yue@gmail.com Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:57936 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729235AbeGVQXd (ORCPT ); Sun, 22 Jul 2018 12:23:33 -0400 Content-Disposition: inline In-Reply-To: <1532196242-2998-2-git-send-email-xiangxia.m.yue@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sat, Jul 21, 2018 at 11:03:59AM -0700, xiangxia.m.yue@gmail.com wrote: > From: Tonghao Zhang > > This patch changes the way that lock all vqs > at the same, to lock them one by one. It will > be used for next patch to avoid the deadlock. > > Signed-off-by: Tonghao Zhang > Acked-by: Jason Wang > Signed-off-by: Jason Wang > --- > drivers/vhost/vhost.c | 24 +++++++----------------- > 1 file changed, 7 insertions(+), 17 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index a502f1a..a1c06e7 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -294,8 +294,11 @@ static void vhost_vq_meta_reset(struct vhost_dev *d) > { > int i; > > - for (i = 0; i < d->nvqs; ++i) > + for (i = 0; i < d->nvqs; ++i) { > + mutex_lock(&d->vqs[i]->mutex); > __vhost_vq_meta_reset(d->vqs[i]); > + mutex_unlock(&d->vqs[i]->mutex); > + } > } > > static void vhost_vq_reset(struct vhost_dev *dev, > @@ -890,20 +893,6 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq, > #define vhost_get_used(vq, x, ptr) \ > vhost_get_user(vq, x, ptr, VHOST_ADDR_USED) > > -static void vhost_dev_lock_vqs(struct vhost_dev *d) > -{ > - int i = 0; > - for (i = 0; i < d->nvqs; ++i) > - mutex_lock_nested(&d->vqs[i]->mutex, i); > -} > - > -static void vhost_dev_unlock_vqs(struct vhost_dev *d) > -{ > - int i = 0; > - for (i = 0; i < d->nvqs; ++i) > - mutex_unlock(&d->vqs[i]->mutex); > -} > - > static int vhost_new_umem_range(struct vhost_umem *umem, > u64 start, u64 size, u64 end, > u64 userspace_addr, int perm) > @@ -953,7 +942,10 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d, > if (msg->iova <= vq_msg->iova && > msg->iova + msg->size - 1 > vq_msg->iova && > vq_msg->type == VHOST_IOTLB_MISS) { > + mutex_lock(&node->vq->mutex); > vhost_poll_queue(&node->vq->poll); > + mutex_unlock(&node->vq->mutex); > + > list_del(&node->node); > kfree(node); > } > @@ -985,7 +977,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, > int ret = 0; > > mutex_lock(&dev->mutex); > - vhost_dev_lock_vqs(dev); > switch (msg->type) { > case VHOST_IOTLB_UPDATE: > if (!dev->iotlb) { > @@ -1019,7 +1010,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, > break; > } > > - vhost_dev_unlock_vqs(dev); > mutex_unlock(&dev->mutex); > > return ret; I do prefer the finer-grained locking but I remember we discussed something like this in the past and Jason saw issues with such a locking. Jason? > -- > 1.8.3.1