Re: [Xen-devel] [PATCH] improve the error message in "xl list --long"

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Oct 24, 2013 at 03:30:57PM +0800, Bamvor Jian Zhang wrote:
> it is a bug reported by customer, xl will output the following message
> when issue "xl list --long domain_name":
> Domain name must be specified.
> 
> the error message is completely unclear. this error is because such
> domain is not created by xl itself. xl could saw the domain name but
> could not get the domain configuration.
> 

The root cause is that there is no sotred config file in xl's private
storage. This can be caused by the reason you stated above.

Another posibility is that Xen fails to clean up a domain after its
death. That domain remains visible in Xen, however at that time the
stored config file is already deleted.

IMHO we can skip this domain without printing this info. Or this info
needs to cover all the situations.

Wei.

> Signed-off-by: Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> ---
> change since RFC:
> raise the error in list_domains_details instead of modifying the 
> libxl_userdata_retrieve itself.
> there are four command would invoke the libxl_userdata_retrieve: create, 
> save, migrate, list. issue create command mean the domain is not called
> from other toolstack, and there is libxl_userdata_retrieve return value
> check in save and migrate. So, the only place need to check is in
> list_domain_details.
> 
>  tools/libxl/xl_cmdimpl.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index a8261be..81bdb91 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -3064,6 +3064,11 @@ static void list_domains_details(const libxl_dominfo 
> *info, int nb_domain)
>          rc = libxl_userdata_retrieve(ctx, info[i].domid, "xl", &data, &len);
>          if (rc)
>              continue;
> +        if (len == 0) {
> +            fprintf(stderr, "No xl userdata found. Is domain id"
> +                    "'%u' owned by another toolstack?", info[i].domid);
> +            continue;
> +        }
>          CHK_ERRNO(asprintf(&config_source, "<domid %d data>", 
> info[i].domid));
>          libxl_domain_config_init(&d_config);
>          parse_config_data(config_source, (char *)data, len, &d_config, NULL);
> -- 
> 1.8.1.4
> 
> 
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