Re: [PATCH v11 10/27] migration: push Error **errp into qemu_loadvm_section_start_full()

[Fabiano Rosas <farosas@suse.de>]

Arun Menon <armenon@redhat.com> writes:

> This is an incremental step in converting vmstate loading
> code to report error via Error objects instead of directly
> printing it to console/monitor.
> It is ensured that qemu_loadvm_section_start_full() must report an error
> in errp, in case of failure.
>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Signed-off-by: Arun Menon <armenon@redhat.com>
> ---
>  migration/savevm.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 9ec07892cd6ea666431410657c840b6325377d97..77408347c1f1ca7eb3a04f8f130c20a5a81f6db2 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2724,21 +2724,21 @@ static bool check_section_footer(QEMUFile *f, SaveStateEntry *se)
>  }
>  
>  static int
> -qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
> +qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type, Error **errp)
>  {
> +    ERRP_GUARD();
>      bool trace_downtime = (type == QEMU_VM_SECTION_FULL);
>      uint32_t instance_id, version_id, section_id;
>      int64_t start_ts, end_ts;
>      SaveStateEntry *se;
>      char idstr[256];
>      int ret;
> -    Error *local_err = NULL;
>  
>      /* Read section start */
>      section_id = qemu_get_be32(f);
>      if (!qemu_get_counted_string(f, idstr)) {
> -        error_report("Unable to read ID string for section %u",
> -                     section_id);
> +        error_setg(errp, "Unable to read ID string for section %u",
> +                   section_id);
>          return -EINVAL;
>      }
>      instance_id = qemu_get_be32(f);
> @@ -2746,8 +2746,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
>  
>      ret = qemu_file_get_error(f);
>      if (ret) {
> -        error_report("%s: Failed to read instance/version ID: %d",
> -                     __func__, ret);
> +        error_setg(errp, "Failed to read instance/version ID: %d", ret);
>          return ret;
>      }
>  
> @@ -2756,17 +2755,17 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
>      /* Find savevm section */
>      se = find_se(idstr, instance_id);
>      if (se == NULL) {
> -        error_report("Unknown savevm section or instance '%s' %"PRIu32". "
> -                     "Make sure that your current VM setup matches your "
> -                     "saved VM setup, including any hotplugged devices",
> -                     idstr, instance_id);
> +        error_setg(errp, "Unknown savevm section or instance '%s' %"PRIu32". "

Drop the "savevm" please.

> +                   "Make sure that your current VM setup matches your "
> +                   "saved VM setup, including any hotplugged devices",
> +                   idstr, instance_id);
>          return -EINVAL;
>      }
>  
>      /* Validate version */
>      if (version_id > se->version_id) {
> -        error_report("savevm: unsupported version %d for '%s' v%d",
> -                     version_id, idstr, se->version_id);
> +        error_setg(errp, "savevm: unsupported version %d for '%s' v%d",

Same.

> +                   version_id, idstr, se->version_id);
>          return -EINVAL;
>      }
>      se->load_version_id = version_id;
> @@ -2774,7 +2773,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
>  
>      /* Validate if it is a device's state */
>      if (xen_enabled() && se->is_ram) {
> -        error_report("loadvm: %s RAM loading not allowed on Xen", idstr);
> +        error_setg(errp, "loadvm: %s RAM loading not allowed on Xen", idstr);
>          return -EINVAL;
>      }
>  
> @@ -2782,11 +2781,11 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
>          start_ts = qemu_clock_get_us(QEMU_CLOCK_REALTIME);
>      }
>  
> -    ret = vmstate_load(f, se, &local_err);
> +    ret = vmstate_load(f, se, errp);
>      if (ret < 0) {
> -        error_report("error while loading state for instance 0x%"PRIx32" of"
> -                     " device '%s'", instance_id, idstr);
> -        warn_report_err(local_err);
> +        error_prepend(errp,
> +                      "error while loading state for instance 0x%"PRIx32" of"
> +                      " device '%s': ", instance_id, idstr);
>          return ret;
>      }
>  
> @@ -2797,6 +2796,9 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type)
>      }
>  
>      if (!check_section_footer(f, se)) {
> +        error_setg(errp, "Reading footer section of instance "
> +                   "0x%"PRIx32" of device '%s' for version_id: %d failed",
> +                   instance_id, idstr, version_id);

check_section_footer() already has messages saying something went wrong
with the footer. Make sure you're not duplicating information. If
necessary, trim it either here or there.

>          return -EINVAL;
>      }
>  
> @@ -3103,7 +3105,7 @@ retry:
>          switch (section_type) {
>          case QEMU_VM_SECTION_START:
>          case QEMU_VM_SECTION_FULL:
> -            ret = qemu_loadvm_section_start_full(f, section_type);
> +            ret = qemu_loadvm_section_start_full(f, section_type, errp);
>              if (ret < 0) {
>                  goto out;
>              }