Re: [PATCH v3 22/23] vhost-user-blk: add some useful trace-points

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 15, 2025 at 05:58:06PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> Reviewed-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
> Reviewed-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
> ---
>  hw/block/trace-events     | 10 ++++++++++
>  hw/block/vhost-user-blk.c | 19 +++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/hw/block/trace-events b/hw/block/trace-events
> index cc9a9f2460..dbaa5ca6cb 100644
> --- a/hw/block/trace-events
> +++ b/hw/block/trace-events
> @@ -58,6 +58,16 @@ virtio_blk_handle_zone_mgmt(void *vdev, void *req, uint8_t op, int64_t sector, i
>  virtio_blk_handle_zone_reset_all(void *vdev, void *req, int64_t sector, int64_t len) "vdev %p req %p sector 0x%" PRIx64 " cap 0x%" PRIx64 ""
>  virtio_blk_handle_zone_append(void *vdev, void *req, int64_t sector) "vdev %p req %p, append sector 0x%" PRIx64 ""
>  
> +# vhost-user-blk.c
> +vhost_user_blk_start_in(void *vdev) "vdev %p"
> +vhost_user_blk_start_out(void *vdev) "vdev %p"
> +vhost_user_blk_stop_in(void *vdev) "vdev %p"
> +vhost_user_blk_stop_out(void *vdev) "vdev %p"
> +vhost_user_blk_connect_in(void *vdev) "vdev %p"
> +vhost_user_blk_connect_out(void *vdev) "vdev %p"
> +vhost_user_blk_device_realize_in(void *vdev) "vdev %p"
> +vhost_user_blk_device_realize_out(void *vdev) "vdev %p"
> +
>  # hd-geometry.c
>  hd_geometry_lchs_guess(void *blk, int cyls, int heads, int secs) "blk %p LCHS %d %d %d"
>  hd_geometry_guess(void *blk, uint32_t cyls, uint32_t heads, uint32_t secs, int trans) "blk %p CHS %u %u %u trans %d"
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index de7a810c93..a5daed4346 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -31,6 +31,7 @@
>  #include "hw/virtio/virtio-access.h"
>  #include "system/system.h"
>  #include "system/runstate.h"
> +#include "trace.h"
>  
>  static const int user_feature_bits[] = {
>      VIRTIO_BLK_F_SIZE_MAX,
> @@ -137,6 +138,8 @@ static int vhost_user_blk_start(VirtIODevice *vdev, Error **errp)
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>      int i, ret;
>  
> +    trace_vhost_user_blk_start_in(vdev);
> +
>      if (!k->set_guest_notifiers) {
>          error_setg(errp, "binding does not support guest notifiers");
>          return -ENOSYS;
> @@ -192,6 +195,8 @@ static int vhost_user_blk_start(VirtIODevice *vdev, Error **errp)
>      }
>      s->started_vu = true;
>  
> +    trace_vhost_user_blk_start_out(vdev);
> +
>      return ret;
>  
>  err_guest_notifiers:
> @@ -212,6 +217,8 @@ static int vhost_user_blk_stop(VirtIODevice *vdev)
>      int ret;
>      bool force_stop = false;
>  
> +    trace_vhost_user_blk_stop_in(vdev);
> +
>      if (!s->started_vu) {
>          return 0;
>      }
> @@ -233,6 +240,9 @@ static int vhost_user_blk_stop(VirtIODevice *vdev)
>      }
>  
>      vhost_dev_disable_notifiers(&s->dev, vdev);
> +
> +    trace_vhost_user_blk_stop_out(vdev);
> +
>      return ret;
>  }
>  
> @@ -340,6 +350,8 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
>      VHostUserBlk *s = VHOST_USER_BLK(vdev);
>      int ret = 0;
>  
> +    trace_vhost_user_blk_connect_in(vdev);
> +
>      if (s->connected) {
>          return 0;
>      }
> @@ -365,6 +377,8 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
>          ret = vhost_user_blk_start(vdev, errp);
>      }
>  
> +    trace_vhost_user_blk_connect_out(vdev);
> +
>      return ret;
>  }
>  
> @@ -455,6 +469,8 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
>      int retries;
>      int i, ret;
>  
> +    trace_vhost_user_blk_device_realize_in(vdev);
> +
>      if (!s->chardev.chr) {
>          error_setg(errp, "chardev is mandatory");
>          return;
> @@ -514,6 +530,9 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
>      qemu_chr_fe_set_handlers(&s->chardev,  NULL, NULL,
>                               vhost_user_blk_event, NULL, (void *)dev,
>                               NULL, true);
> +
> +    trace_vhost_user_blk_device_realize_out(vdev);
> +
>      return;
>  
>  virtio_err:


Is it ok that on error there's an in trace but not an out trace?

> -- 
> 2.48.1