From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tonghao Zhang Subject: Re: [PATCH net-next v6 1/4] net: vhost: lock the vqs one by one Date: Wed, 25 Jul 2018 20:05:56 +0800 Message-ID: References: <1532196242-2998-1-git-send-email-xiangxia.m.yue@gmail.com> <1532196242-2998-2-git-send-email-xiangxia.m.yue@gmail.com> <20180722182448-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180722182448-mutt-send-email-mst@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: mst@redhat.com Cc: Linux Kernel Network Developers , virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Sun, Jul 22, 2018 at 11:26 PM Michael S. Tsirkin wrote: > > 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. This change is suggested by Jason. Should I send new version because the patch 3 is changed. > Jason? > > > -- > > 1.8.3.1