| Message ID | 20200907105220.27776-2-lingshan.zhu@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] vhost: remove mutex ops in vhost_set_backend_features | expand |
On Tue, Sep 08, 2020 at 09:00:19PM +0800, Zhu, Lingshan wrote: > > On 9/8/2020 8:05 PM, Michael S. Tsirkin wrote: > > On Mon, Sep 07, 2020 at 06:52:19PM +0800, Zhu Lingshan wrote: > > In vhost_vdpa ioctl SET_BACKEND_FEATURES path, currect code > would try to acquire vhost dev mutex twice > (first shown in vhost_vdpa_unlocked_ioctl), which can lead > to a dead lock issue. > This commit removed mutex operations in vhost_set_backend_features. > As a compensation for vhost_net, a followinig commit will add > needed mutex lock/unlock operations in a new function > vhost_net_set_backend_features() which is a wrap of > vhost_set_backend_features(). > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> > > I think you need to squash these two or reorder, we can't first > make code racy then fix it up. > > OK, I will send a V2 series with Jason's fixes tomorrow (handle SET/GET_BACKEND_FEATURES in vhost_vdpa ioctl than vring ioctl). > > Thanks, > BR > Zhu Lingshan this never materialized ... > > > --- > drivers/vhost/vhost.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index b45519ca66a7..e03c9e6f058f 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2591,14 +2591,12 @@ void vhost_set_backend_features(struct vhost_dev *dev, u64 features) > struct vhost_virtqueue *vq; > int i; > > - mutex_lock(&dev->mutex); > for (i = 0; i < dev->nvqs; ++i) { > vq = dev->vqs[i]; > mutex_lock(&vq->mutex); > vq->acked_backend_features = features; > mutex_unlock(&vq->mutex); > } > - mutex_unlock(&dev->mutex); > } > EXPORT_SYMBOL_GPL(vhost_set_backend_features); > > -- > 2.18.4 >
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index b45519ca66a7..e03c9e6f058f 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2591,14 +2591,12 @@ void vhost_set_backend_features(struct vhost_dev *dev, u64 features) struct vhost_virtqueue *vq; int i; - mutex_lock(&dev->mutex); for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; mutex_lock(&vq->mutex); vq->acked_backend_features = features; mutex_unlock(&vq->mutex); } - mutex_unlock(&dev->mutex); } EXPORT_SYMBOL_GPL(vhost_set_backend_features);
In vhost_vdpa ioctl SET_BACKEND_FEATURES path, currect code would try to acquire vhost dev mutex twice (first shown in vhost_vdpa_unlocked_ioctl), which can lead to a dead lock issue. This commit removed mutex operations in vhost_set_backend_features. As a compensation for vhost_net, a followinig commit will add needed mutex lock/unlock operations in a new function vhost_net_set_backend_features() which is a wrap of vhost_set_backend_features(). Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> --- drivers/vhost/vhost.c | 2 -- 1 file changed, 2 deletions(-)