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Subject: Re: [PATCH net-next v1 4/5] virtio_ring: add event idx support in packed ring
On 2018å07æ09æ 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
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