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SubjectRe: [PATCH] scsi: virtio_scsi: don't send sc payload with tmfs
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On 27/02/19 17:10, Felipe Franciosi wrote:
> The virtio scsi spec defines struct virtio_scsi_ctrl_tmf as a set of
> device-readable records and a single device-writable response entry:
>
> struct virtio_scsi_ctrl_tmf
> {
> // Device-readable part
> le32 type;
> le32 subtype;
> u8 lun[8];
> le64 id;
> // Device-writable part
> u8 response;
> }
>
> The above should be organised as two descriptor entries (or potentially
> more if using VIRTIO_F_ANY_LAYOUT), but without any extra data after
> "le64 id" or after "u8 response".
>
> The Linux driver doesn't respect that, with virtscsi_abort() and
> virtscsi_device_reset() setting cmd->sc before calling virtscsi_tmf().
> It results in the original scsi command payload (or writable buffers)
> added to the tmf.
>
> This fixes the problem by leaving cmd->sc zeroed out, which makes
> virtscsi_kick_cmd() add the tmf to the control vq without any payload.

Indeed, all that the completion routine needs is cmd->comp, which is set
directly in virtscsi_tmf.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org

>
> Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
> ---
> drivers/scsi/virtio_scsi.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 772b976..464cba5 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -594,7 +594,6 @@ static int virtscsi_device_reset(struct scsi_cmnd *sc)
> return FAILED;
>
> memset(cmd, 0, sizeof(*cmd));
> - cmd->sc = sc;
> cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
> .type = VIRTIO_SCSI_T_TMF,
> .subtype = cpu_to_virtio32(vscsi->vdev,
> @@ -653,7 +652,6 @@ static int virtscsi_abort(struct scsi_cmnd *sc)
> return FAILED;
>
> memset(cmd, 0, sizeof(*cmd));
> - cmd->sc = sc;
> cmd->req.tmf = (struct virtio_scsi_ctrl_tmf_req){
> .type = VIRTIO_SCSI_T_TMF,
> .subtype = VIRTIO_SCSI_T_TMF_ABORT_TASK,
>

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