From: Jason Wang <jasowang@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>,
mst@redhat.com, virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
virtio-dev@lists.oasis-open.org
Cc: wexu@redhat.com, jfreimann@redhat.com
Subject: Re: [PATCH net-next v1 4/5] virtio_ring: add event idx support in packed ring
Date: Tue, 10 Jul 2018 13:50:03 +0800 [thread overview]
Message-ID: <9ee31221-9f4a-f1c5-0f0b-8d178bb536e9@redhat.com> (raw)
In-Reply-To: <20180709072241.8886-5-tiwei.bie@intel.com>
On 2018年07月09日 15:22, Tiwei Bie wrote:
> @@ -1059,9 +1059,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
> * suppressions. */
> virtio_mb(vq->weak_barriers);
>
> + old = vq->next_avail_idx - vq->num_added;
> + new = vq->next_avail_idx;
> + vq->num_added = 0;
> +
> snapshot = *(u32 *)vq->vring_packed.device;
I think we should use READ_ONCE() to prevent compiler from re-reading.
> + off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0xffff));
> flags = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot >> 16)) & 0x3;
>
> + wrap_counter = off_wrap >> 15;
> + event_idx = off_wrap & ~(1 << 15);
> + if (wrap_counter != vq->avail_wrap_counter)
> + event_idx -= vq->vring_packed.num;
Thanks
next prev parent reply other threads:[~2018-07-10 5:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 7:22 [PATCH net-next v1 0/5] virtio: support packed ring Tiwei Bie
2018-07-09 7:22 ` [PATCH net-next v1 1/5] virtio: add packed ring definitions Tiwei Bie
2018-07-09 7:22 ` [PATCH net-next v1 2/5] virtio_ring: support creating packed ring Tiwei Bie
2018-07-09 7:22 ` [PATCH net-next v1 3/5] virtio_ring: add packed ring support Tiwei Bie
2018-07-09 7:22 ` [PATCH net-next v1 4/5] virtio_ring: add event idx support in packed ring Tiwei Bie
2018-07-10 5:50 ` Jason Wang [this message]
2018-07-11 1:09 ` [virtio-dev] " Tiwei Bie
2018-07-09 7:22 ` [PATCH net-next v1 5/5] virtio_ring: enable " Tiwei Bie
2018-07-10 5:51 ` Jason Wang
2018-07-11 1:07 ` Tiwei Bie
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