Re: [PATCH v3 2/2] vhost: Add Error parameter to vhost_scsi_common_start()

[Markus Armbruster <armbru@redhat.com>]

Li Feng <fengli@smartx.com> writes:

> Add a Error parameter to report the real error, like vhost-user-blk.
>
> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
>  hw/scsi/vhost-scsi-common.c           | 16 +++++++++-------
>  hw/scsi/vhost-scsi.c                  |  5 +++--
>  hw/scsi/vhost-user-scsi.c             | 14 ++++++++------
>  include/hw/virtio/vhost-scsi-common.h |  2 +-
>  4 files changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/hw/scsi/vhost-scsi-common.c b/hw/scsi/vhost-scsi-common.c
> index a61cd0e907..4c8637045d 100644
> --- a/hw/scsi/vhost-scsi-common.c
> +++ b/hw/scsi/vhost-scsi-common.c
> @@ -16,6 +16,7 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qapi/error.h"
>  #include "qemu/error-report.h"
>  #include "qemu/module.h"
>  #include "hw/virtio/vhost.h"
> @@ -25,7 +26,7 @@
>  #include "hw/virtio/virtio-access.h"
>  #include "hw/fw-path-provider.h"
>  
> -int vhost_scsi_common_start(VHostSCSICommon *vsc)
> +int vhost_scsi_common_start(VHostSCSICommon *vsc, Error **errp)
>  {
>      int ret, i;
>      VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
> @@ -35,18 +36,19 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
>      VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vsc;
>  
>      if (!k->set_guest_notifiers) {
> -        error_report("binding does not support guest notifiers");
> +        error_setg(errp, "binding does not support guest notifiers");
>          return -ENOSYS;
>      }
>  
>      ret = vhost_dev_enable_notifiers(&vsc->dev, vdev);
>      if (ret < 0) {
> +        error_setg_errno(errp, -ret, "Error enabling host notifiers");

Looks like the error is silent before your patch.  Correct?

>          return ret;
>      }
>  
>      ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, true);
>      if (ret < 0) {
> -        error_report("Error binding guest notifier");
> +        error_setg_errno(errp, -ret, "Error binding guest notifier");

Error message now provides more detail.

>          goto err_host_notifiers;
>      }
>  
> @@ -54,7 +56,7 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
>  
>      ret = vhost_dev_prepare_inflight(&vsc->dev, vdev);
>      if (ret < 0) {
> -        error_report("Error setting inflight format: %d", -ret);
> +        error_setg_errno(errp, -ret, "Error setting inflight format");

Error message now shows errno in human-readable form.

>          goto err_guest_notifiers;
>      }
>  
> @@ -64,21 +66,21 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
>                                          vs->conf.virtqueue_size,
>                                          vsc->inflight);
>              if (ret < 0) {
> -                error_report("Error getting inflight: %d", -ret);
> +                error_setg_errno(errp, -ret, "Error getting inflight");

Likewise.

>                  goto err_guest_notifiers;
>              }
>          }
>  
>          ret = vhost_dev_set_inflight(&vsc->dev, vsc->inflight);
>          if (ret < 0) {
> -            error_report("Error setting inflight: %d", -ret);
> +            error_setg_errno(errp, -ret, "Error setting inflight");

Likewise.

>              goto err_guest_notifiers;
>          }
>      }
>  
>      ret = vhost_dev_start(&vsc->dev, vdev, true);
>      if (ret < 0) {
> -        error_report("Error start vhost dev");
> +        error_setg_errno(errp, -ret, "Error starting vhost dev");

Likewise.

>          goto err_guest_notifiers;
>      }
>  
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index 443f67daa4..01a3ab4277 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -75,6 +75,7 @@ static int vhost_scsi_start(VHostSCSI *s)
>      int ret, abi_version;
>      VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
>      const VhostOps *vhost_ops = vsc->dev.vhost_ops;
> +    Error *local_err = NULL;
>  
>      ret = vhost_ops->vhost_scsi_get_abi_version(&vsc->dev, &abi_version);
>      if (ret < 0) {
> @@ -88,14 +89,14 @@ static int vhost_scsi_start(VHostSCSI *s)
>          return -ENOSYS;
>      }
>  
> -    ret = vhost_scsi_common_start(vsc);
> +    ret = vhost_scsi_common_start(vsc, &local_err);
>      if (ret < 0) {
>          return ret;
>      }
>  
>      ret = vhost_scsi_set_endpoint(s);
>      if (ret < 0) {
> -        error_report("Error setting vhost-scsi endpoint");
> +        error_reportf_err(local_err, "Error setting vhost-scsi endpoint");
>          vhost_scsi_common_stop(vsc);
>      }
>  
> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
> index e931df9f5b..62fc98bb1c 100644
> --- a/hw/scsi/vhost-user-scsi.c
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -43,12 +43,12 @@ enum VhostUserProtocolFeature {
>      VHOST_USER_PROTOCOL_F_RESET_DEVICE = 13,
>  };
>  
> -static int vhost_user_scsi_start(VHostUserSCSI *s)
> +static int vhost_user_scsi_start(VHostUserSCSI *s, Error **errp)
>  {
>      VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
>      int ret;
>  
> -    ret = vhost_scsi_common_start(vsc);
> +    ret = vhost_scsi_common_start(vsc, errp);
>      s->started_vu = (ret < 0 ? false : true);
>  
>      return ret;
> @@ -73,6 +73,7 @@ static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
>      VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
>      VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
>      bool should_start = virtio_device_should_start(vdev, status);
> +    Error *local_err = NULL;
>      int ret;
>  
>      if (!s->connected) {
> @@ -84,9 +85,10 @@ static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
>      }
>  
>      if (should_start) {
> -        ret = vhost_user_scsi_start(s);
> +        ret = vhost_user_scsi_start(s, &local_err);
>          if (ret < 0) {
> -            error_report("unable to start vhost-user-scsi: %s", strerror(-ret));
> +            error_reportf_err(local_err, "unable to start vhost-user-scsi: %s",
> +                              strerror(-ret));
>              qemu_chr_fe_disconnect(&vs->conf.chardev);
>          }
>      } else {
> @@ -139,7 +141,7 @@ static void vhost_user_scsi_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>       * Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
>       * vhost here instead of waiting for .set_status().
>       */
> -    ret = vhost_user_scsi_start(s);
> +    ret = vhost_user_scsi_start(s, &local_err);
>      if (ret < 0) {
>          error_reportf_err(local_err, "vhost-user-scsi: vhost start failed: ");

The error_reportf_err() is wrong before the patch, as I just pointed out
in my review of "[PATCH v3 5/5] vhost-user-scsi: start vhost when guest
kicks".  It is correct afterwards.

>          qemu_chr_fe_disconnect(&vs->conf.chardev);
> @@ -184,7 +186,7 @@ static int vhost_user_scsi_connect(DeviceState *dev, Error **errp)
>  
>      /* restore vhost state */
>      if (virtio_device_started(vdev, vdev->status)) {
> -        ret = vhost_user_scsi_start(s);
> +        ret = vhost_user_scsi_start(s, errp);
>          if (ret < 0) {
>              return ret;
>          }

Wrong before the patch, as I just pointed out in my review of "[PATCH v3
4/5] vhost-user-scsi: support reconnect to backend".  Correct afterwards.

> diff --git a/include/hw/virtio/vhost-scsi-common.h b/include/hw/virtio/vhost-scsi-common.h
> index 18f115527c..c5d2c09455 100644
> --- a/include/hw/virtio/vhost-scsi-common.h
> +++ b/include/hw/virtio/vhost-scsi-common.h
> @@ -39,7 +39,7 @@ struct VHostSCSICommon {
>      struct vhost_inflight *inflight;
>  };
>  
> -int vhost_scsi_common_start(VHostSCSICommon *vsc);
> +int vhost_scsi_common_start(VHostSCSICommon *vsc, Error **errp);
>  void vhost_scsi_common_stop(VHostSCSICommon *vsc);
>  char *vhost_scsi_common_get_fw_dev_path(FWPathProvider *p, BusState *bus,
>                                          DeviceState *dev);

Please mention in the commit message that error messages improve, and
silent errors are now reported.