[libvirt] [PATCH] lxcSetSchedulerParameters: reverse order of tests; improve a diagnostic

[Eric Blake]

On 05/11/2010 07:51 AM, Jim Meyering wrote:
> Investigating something else in the vicinity,
> I noticed that the ordering of tests was backwards.
> Here's the fix for that.
> 
> Also, looking at the following code, I saw that failure of
> virCgroupSetCpuShares could evoke no diagnostic.
> Now it does.
> 
>>From bc3404d9f12c42cf883a43395fee6fc14c952b2c Mon Sep 17 00:00:00 2001
> From: Jim Meyering <meyering at redhat.com>
> Date: Tue, 11 May 2010 15:43:32 +0200
> Subject: [PATCH] lxcSetSchedulerParameters: reverse order of tests; diagnose a failure
> 
> * src/lxc/lxc_driver.c (lxcSetSchedulerParameters): Ensure that
> "->field" is "cpu_shares" before possibly giving a diagnostic about
> a type for a "cpu_shares" value.
> Also, virCgroupSetCpuShares could fail without evoking a diagnostic.
> Add one.
> ---
>  src/lxc/lxc_driver.c |   19 ++++++++++++-------
>  1 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
> index fc0df37..5636eee 100644
> --- a/src/lxc/lxc_driver.c
> +++ b/src/lxc/lxc_driver.c
> @@ -2054,18 +2054,23 @@ static int lxcSetSchedulerParameters(virDomainPtr domain,
> 
>      for (i = 0; i < nparams; i++) {
>          virSchedParameterPtr param = &params[i];
> +
> +        if (STRNEQ(param->field, "cpu_shares")) {
> +            lxcError(VIR_ERR_INVALID_ARG,
> +                     _("Invalid parameter `%s'"), param->field);
> +            goto cleanup;
> +        }
> +
>          if (param->type != VIR_DOMAIN_SCHED_FIELD_ULLONG) {
>              lxcError(VIR_ERR_INVALID_ARG, "%s",
> -                     _("Invalid type for cpu_shares tunable, expected a 'ullong'"));
> +                 _("Invalid type for cpu_shares tunable, expected a 'ullong'"));

Why the indentation change here?

>              goto cleanup;
>          }
> 
> -        if (STREQ(param->field, "cpu_shares")) {
> -            if (virCgroupSetCpuShares(group, params[i].value.ul) != 0)
> -                goto cleanup;
> -        } else {
> -            lxcError(VIR_ERR_INVALID_ARG,
> -                     _("Invalid parameter `%s'"), param->field);
> +        int rc = virCgroupSetCpuShares(group, params[i].value.ul);
> +        if (rc != 0) {
> +            virReportSystemError(-rc, _("failed to set cpu_shares=%llu"),
> +                                 params[i].value.ul);
>              goto cleanup;
>          }
>      }

ACK.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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