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Re: [Qemu-devel] [PATCH] virtio-scsi: fix "written length" field in the
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-scsi: fix "written length" field in the used ring |
Date: |
Mon, 27 Apr 2015 15:23:54 +0200 |
On Mon, Apr 27, 2015 at 02:29:25PM +0200, Paolo Bonzini wrote:
> qsgl->size is the size of the data field after the request or
> response header (virtio-scsi currently supports only one such
> field; bidirectional requests are not supported). However,
> the used ring's len field is not concerned about the field
> after the request header, so do not count it unless req->mode
> signals the request was a read.
>
> Also, do not report that anything was written if the request
> failed, and subtract any residual bytes in case of buffer underrun.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
Acked-by: Michael S. Tsirkin <address@hidden>
Pls merge through the storage tree.
Also, can you pls fix up blk similarly?
> ---
> hw/scsi/virtio-scsi.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index c9bea06..4995f6e 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -65,6 +65,19 @@ void virtio_scsi_free_req(VirtIOSCSIReq *req)
> g_slice_free1(sizeof(*req) + vs->cdb_size, req);
> }
>
> +static size_t virtio_scsi_written_length(VirtIODevice *vdev, VirtIOSCSIReq
> *req)
> +{
> + size_t sz = req->resp_iov.size;
> +
> + if (req->sreq &&
> + req->mode == SCSI_XFER_FROM_DEV &&
> + req->resp.cmd.response == VIRTIO_SCSI_S_OK) {
> + sz += req->qsgl.size - virtio_tswap32(vdev, req->resp.cmd.resid);
> + }
> +
> + return sz;
> +}
> +
> static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
> {
> VirtIOSCSI *s = req->dev;
> @@ -76,7 +89,7 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
> assert(req->vq == NULL);
> virtio_scsi_vring_push_notify(req);
> } else {
> - virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
> + virtqueue_push(vq, &req->elem, virtio_scsi_written_length(vdev,
> req));
> virtio_notify(vdev, vq);
> }
>
> --
> 2.3.5