On Sun, Jul 22, 2018 at 11:26 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Sat, Jul 21, 2018 at 11:03:59AM -0700, xiangxia.m.yue@xxxxxxxxx wrote:
> > From: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
> >
> > 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 <xiangxia.m.yue@xxxxxxxxx>
> > Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> > 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
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