Re: [PATCH v11 14/40] virtio_ring: split: introduce virtqueue_resize_split()
From: Jason Wang <jasowang@redhat.com>
Date: 2022-07-01 09:09:35
Also in:
bpf, kvm, linux-remoteproc, linux-s390, linux-um, platform-driver-x86, virtualization
在 2022/6/29 14:56, Xuan Zhuo 写道:
quoted hunk ↗ jump to hunk
virtio ring split supports resize. Only after the new vring is successfully allocated based on the new num, we will release the old vring. In any case, an error is returned, indicating that the vring still points to the old vring. In the case of an error, re-initialize(virtqueue_reinit_split()) the virtqueue to ensure that the vring can be used. In addition, vring_align, may_reduce_num are necessary for reallocating vring, so they are retained for creating vq. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- drivers/virtio/virtio_ring.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 9c83c5e6d5a9..1aaa1e5f9991 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c@@ -212,6 +212,7 @@ struct vring_virtqueue { }; static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num); +static void vring_free(struct virtqueue *_vq); /* * Helpers.@@ -1114,6 +1115,37 @@ static struct virtqueue *vring_create_virtqueue_split( return vq; } +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + struct vring_virtqueue_split vring = {}; + struct virtio_device *vdev = _vq->vdev; + int err; + + err = vring_alloc_queue_split(&vring, vdev, num, vq->split.vring_align, + vq->split.may_reduce_num); + if (err) + goto err;
It's better to have decouple the allocation future more to avoid any rewind here in the future. But the patch should be fine. So Acked-by: Jason Wang <jasowang@redhat.com>
+
+ err = vring_alloc_state_extra_split(&vring);
+ if (err) {
+ vring_free_split(&vring, vdev);
+ goto err;
+ }
+
+ vring_free(&vq->vq);
+
+ virtqueue_init(vq, vring.vring.num);
+ virtqueue_vring_attach_split(vq, &vring);
+ virtqueue_vring_init_split(vq);
+
+ return 0;
+
+err:
+ virtqueue_reinit_split(vq);
+ return -ENOMEM;
+}
+
/*
* Packed ring specific functions - *_packed().