| Message ID | 20181130160553.9739-1-jean-philippe.brucker@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] vhost: fix IOTLB locking | expand |
From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> Date: Fri, 30 Nov 2018 16:05:53 +0000 > Commit 78139c94dc8c ("net: vhost: lock the vqs one by one") moved the vq > lock to improve scalability, but introduced a possible deadlock in > vhost-iotlb. vhost_iotlb_notify_vq() now takes vq->mutex while holding > the device's IOTLB spinlock. And on the vhost_iotlb_miss() path, the > spinlock is taken while holding vq->mutex. > > Since calling vhost_poll_queue() doesn't require any lock, avoid the > deadlock by not taking vq->mutex. > > Fixes: 78139c94dc8c ("net: vhost: lock the vqs one by one") > Acked-by: Jason Wang <jasowang@redhat.com> > Acked-by: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> Applied, thank you.
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 3a5f81a66d34..6b98d8e3a5bf 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -944,10 +944,7 @@ 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); }
Commit 78139c94dc8c ("net: vhost: lock the vqs one by one") moved the vq lock to improve scalability, but introduced a possible deadlock in vhost-iotlb. vhost_iotlb_notify_vq() now takes vq->mutex while holding the device's IOTLB spinlock. And on the vhost_iotlb_miss() path, the spinlock is taken while holding vq->mutex. Since calling vhost_poll_queue() doesn't require any lock, avoid the deadlock by not taking vq->mutex. Fixes: 78139c94dc8c ("net: vhost: lock the vqs one by one") Acked-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> --- drivers/vhost/vhost.c | 3 --- 1 file changed, 3 deletions(-)