On Sun, Feb 05, 2012 at 12:16:01PM +0100, Paolo Bonzini wrote:
> This commit adds basic error handling to the virtio-scsi
> HBA device.  Task management functions are sent synchronously
> via the control virtqueue.
> 
> Cc: linux-scsi <linux-scsi@vger.kernel.org>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: kvm@vger.kernel.org
> Acked-by: Pekka Enberg <penberg@kernel.org> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> 	v3->v4: fixed 32-bit compilation; adjusted call to virtscsi_kick_cmd
> 
> 	v2->v3: added mempool, used GFP_NOIO instead of GFP_ATOMIC,
> 	formatting fixes
> 
> 	v1->v2: use scmd_printk
> 
>  drivers/scsi/virtio_scsi.c |   73 +++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 72 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 3f87ae0..68104cd 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -29,6 +29,7 @@
>  /* Command queue element */
>  struct virtio_scsi_cmd {
>  	struct scsi_cmnd *sc;
> +	struct completion *comp;
>  	union {
>  		struct virtio_scsi_cmd_req       cmd;
>  		struct virtio_scsi_ctrl_tmf_req  tmf;
> @@ -168,11 +169,12 @@ static void virtscsi_req_done(struct virtqueue *vq)
>  	virtscsi_vq_done(vq, virtscsi_complete_cmd);
>  };
>  
> -/* These are still stubs.  */
>  static void virtscsi_complete_free(void *buf)
>  {
>  	struct virtio_scsi_cmd *cmd = buf;
>  
> +	if (cmd->comp)
> +		complete_all(cmd->comp);
>  	mempool_free(cmd, virtscsi_cmd_pool);
>  }
>  
> @@ -306,12 +308,81 @@ out:
>  	return ret;
>  }
>  
> +static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
> +{
> +	DECLARE_COMPLETION_ONSTACK(comp);
> +	int ret;
> +
> +	cmd->comp = &comp;
> +	ret = virtscsi_kick_cmd(vscsi, vscsi->ctrl_vq, cmd,
> +			       sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
> +			       GFP_NOIO);
> +	if (ret < 0)
> +		return FAILED;
> +
> +	wait_for_completion(&comp);
> +	if (cmd->resp.tmf.response != VIRTIO_SCSI_S_OK &&
> +	    cmd->resp.tmf.response != VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
> +		return FAILED;
> +
> +	return SUCCESS;
> +}

Hi Paolo,

This is against v5.