From: Jason Wang <jasowang@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
wexu@redhat.com, jfreimann@redhat.com
Subject: Re: [RFC v3 4/5] virtio_ring: add event idx support in packed ring
Date: Tue, 8 May 2018 13:40:40 +0800 [thread overview]
Message-ID: <12ede490-f674-2b89-d639-266b5fe15466@redhat.com> (raw)
In-Reply-To: <fbe06940-1618-5d34-7321-f4888c5dd1ee@redhat.com>
On 2018年05月08日 11:05, Jason Wang wrote:
>>
>> Because in virtqueue_enable_cb_delayed(), we may set an
>> event_off which is bigger than new and both of them have
>> wrapped. And in this case, although new is smaller than
>> event_off (i.e. the third param -- old), new shouldn't
>> add vq->num, and actually we are expecting a very big
>> idx diff.
>
> Yes, so to calculate distance correctly between event and new, we just
> need to compare the warp counter and return false if it doesn't match
> without the need to try to add vq.num here.
>
> Thanks
Sorry, looks like the following should work, we need add vq.num if
used_wrap_counter does not match:
static bool vhost_vring_packed_need_event(struct vhost_virtqueue *vq,
__u16 off_wrap, __u16 new,
__u16 old)
{
bool wrap = off_wrap >> 15;
int off = off_wrap & ~(1 << 15);
__u16 d1, d2;
if (wrap != vq->used_wrap_counter)
d1 = new + vq->num - off - 1;
else
d1 = new - off - 1;
if (new > old)
d2 = new - old;
else
d2 = new + vq->num - old;
return d1 < d2;
}
Thanks
next prev parent reply other threads:[~2018-05-08 5:40 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-25 5:15 [RFC v3 0/5] virtio: support packed ring Tiwei Bie
2018-04-25 5:15 ` [RFC v3 1/5] virtio: add packed ring definitions Tiwei Bie
2018-04-25 5:15 ` Tiwei Bie
2018-04-25 5:15 ` [RFC v3 2/5] virtio_ring: support creating packed ring Tiwei Bie
2018-04-25 5:15 ` Tiwei Bie
2018-04-25 5:15 ` [RFC v3 3/5] virtio_ring: add packed ring support Tiwei Bie
2018-05-10 7:32 ` Jason Wang
2018-05-10 7:32 ` Jason Wang
2018-05-10 7:34 ` Jason Wang
2018-05-10 7:34 ` Jason Wang
2018-05-10 8:56 ` Tiwei Bie
2018-05-10 8:56 ` Tiwei Bie
2018-05-10 9:49 ` Jason Wang
2018-05-10 10:50 ` Tiwei Bie
2018-05-10 10:50 ` Tiwei Bie
2018-05-10 9:49 ` Jason Wang
2018-04-25 5:15 ` Tiwei Bie
2018-04-25 5:15 ` [RFC v3 4/5] virtio_ring: add event idx support in packed ring Tiwei Bie
2018-05-02 2:51 ` Jason Wang
2018-05-02 2:51 ` Jason Wang
2018-05-02 7:28 ` Tiwei Bie
2018-05-02 13:51 ` Michael S. Tsirkin
2018-05-02 15:12 ` Tiwei Bie
2018-05-02 15:12 ` Tiwei Bie
2018-05-02 15:42 ` Michael S. Tsirkin
2018-05-02 15:42 ` Michael S. Tsirkin
2018-05-03 1:11 ` Tiwei Bie
2018-05-03 1:11 ` Tiwei Bie
2018-05-03 1:44 ` Michael S. Tsirkin
2018-05-03 1:44 ` Michael S. Tsirkin
2018-05-03 2:09 ` Tiwei Bie
2018-05-03 2:09 ` Tiwei Bie
2018-05-03 7:25 ` Jason Wang
2018-05-03 7:25 ` Jason Wang
2018-05-03 13:54 ` Tiwei Bie
2018-05-03 13:54 ` Tiwei Bie
2018-05-08 3:05 ` Jason Wang
2018-05-08 3:05 ` Jason Wang
2018-05-08 5:40 ` Jason Wang [this message]
2018-05-08 6:44 ` Tiwei Bie
2018-05-08 7:16 ` Jason Wang
2018-05-08 7:16 ` Jason Wang
2018-05-08 9:16 ` Tiwei Bie
2018-05-08 9:16 ` Tiwei Bie
2018-05-08 9:34 ` Jason Wang
2018-05-08 9:34 ` Jason Wang
2018-05-08 9:44 ` Tiwei Bie
2018-05-08 9:44 ` Tiwei Bie
2018-05-09 3:43 ` Jason Wang
2018-05-09 3:43 ` Jason Wang
2018-05-08 6:44 ` Tiwei Bie
2018-05-08 5:40 ` Jason Wang
2018-05-02 13:51 ` Michael S. Tsirkin
2018-05-02 7:28 ` Tiwei Bie
2018-05-16 5:01 ` Jason Wang
2018-05-16 5:55 ` Tiwei Bie
2018-05-16 5:55 ` Tiwei Bie
2018-05-16 5:01 ` Jason Wang
2018-04-25 5:15 ` Tiwei Bie
2018-04-25 5:15 ` [RFC v3 5/5] virtio_ring: enable " Tiwei Bie
2018-04-25 5:15 ` Tiwei Bie
2018-04-27 3:56 ` [RFC v3 0/5] virtio: support " Jason Wang
2018-04-27 4:18 ` Michael S. Tsirkin
2018-04-27 6:17 ` Jason Wang
2018-04-27 9:12 ` Tiwei Bie
2018-04-27 9:12 ` Tiwei Bie
2018-04-28 2:45 ` Jason Wang
2018-04-28 2:45 ` Jason Wang
2018-04-27 6:17 ` Jason Wang
2018-04-27 4:18 ` Michael S. Tsirkin
2018-04-27 3:56 ` Jason Wang
2018-05-02 3:49 ` Jason Wang
2018-05-02 3:49 ` Jason Wang
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