[libvirt] [PATCH 1/8] util: Add helpers for getting resctrl group allocs

[Michal Privoznik]

On 01/31/2018 10:41 AM, Martin Kletzander wrote:
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/util/virresctrl.c | 79 +++++++++++++++++++++++++++++++++------------------
>  1 file changed, 52 insertions(+), 27 deletions(-)
> 
> diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
> index 42876c6e2b9b..fa7c28e9b45e 100644
> --- a/src/util/virresctrl.c
> +++ b/src/util/virresctrl.c
> @@ -1041,6 +1041,53 @@ virResctrlAllocParse(virResctrlInfoPtr resctrl,
>  }
>  
>  
> +static int
> +virResctrlAllocGetGroup(virResctrlInfoPtr resctrl,
> +                        const char *groupname,
> +                        virResctrlAllocPtr *alloc)
> +{
> +    char *schemata = NULL;
> +    int rv = virFileReadValueString(&schemata,
> +                                     SYSFS_RESCTRL_PATH
> +                                     "/%s/schemata",
> +                                     groupname);
> +
> +    if (rv < 0)
> +        return rv;

I guess we need to set *alloc = NULL before returning. Because with this
patch the function may or may not do that when returning an error. But
it's just cosmetics.

> +
> +    *alloc = virResctrlAllocNew();
> +    if (!*alloc)
> +        goto error;
> +
> +    if (virResctrlAllocParse(resctrl, *alloc, schemata) < 0)
> +        goto error;
> +
> +    VIR_FREE(schemata);
> +    return 0;
> +
> + error:
> +    VIR_FREE(schemata);
> +    virObjectUnref(*alloc);
> +    *alloc = NULL;
> +    return -1;
> +}
> +
> +
> +static virResctrlAllocPtr
> +virResctrlAllocGetDefault(virResctrlInfoPtr resctrl)
> +{
> +    virResctrlAllocPtr ret = NULL;
> +
> +    if (virResctrlAllocGetGroup(resctrl, ".", &ret) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("Could not read schemata file for the default group"));
> +        return NULL;

No need to report an error. virResctrlAllocGetGroup() calls functions
which report error on failure. But this is more user friendly error
message than 'unable to open /sys/blah: Bad address'. Your call.

> +    }
> +
> +    return ret;
> +}
> +
> +
>  static void
>  virResctrlAllocSubtractPerType(virResctrlAllocPerTypePtr dst,
>                                 virResctrlAllocPerTypePtr src)
> @@ -1141,7 +1188,6 @@ virResctrlAllocGetUnused(virResctrlInfoPtr resctrl)
>      virResctrlAllocPtr alloc = NULL;
>      struct dirent *ent = NULL;
>      DIR *dirp = NULL;
> -    char *schemata = NULL;
>      int rv = -1;
>  
>      if (virResctrlInfoIsEmpty(resctrl)) {
> @@ -1154,22 +1200,12 @@ virResctrlAllocGetUnused(virResctrlInfoPtr resctrl)
>      if (!ret)
>          return NULL;
>  
> -    if (virFileReadValueString(&schemata,
> -                               SYSFS_RESCTRL_PATH
> -                               "/schemata") < 0) {
> -        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                       _("Could not read schemata file for the default group"));
> -        goto error;
> -    }
> -
> -    alloc = virResctrlAllocNew();
> +    alloc = virResctrlAllocGetDefault(resctrl);
>      if (!alloc)
>          goto error;
>  
> -    if (virResctrlAllocParse(resctrl, alloc, schemata) < 0)
> -        goto error;
> -
>      virResctrlAllocSubtract(ret, alloc);
> +    virObjectUnref(alloc);
>  
>      if (virDirOpen(&dirp, SYSFS_RESCTRL_PATH) < 0)
>          goto error;
> @@ -1178,11 +1214,7 @@ virResctrlAllocGetUnused(virResctrlInfoPtr resctrl)
>          if (STREQ(ent->d_name, "info"))
>              continue;
>  
> -        VIR_FREE(schemata);
> -        rv = virFileReadValueString(&schemata,
> -                                    SYSFS_RESCTRL_PATH
> -                                    "/%s/schemata",
> -                                    ent->d_name);
> +        rv = virResctrlAllocGetGroup(resctrl, ent->d_name, &alloc);
>          if (rv == -2)
>              continue;

Unfortunately, not visible in the context but the same 'error message
overwrite' problem.

>  
> @@ -1193,15 +1225,9 @@ virResctrlAllocGetUnused(virResctrlInfoPtr resctrl)
>              goto error;
>          }
>  
> -        virObjectUnref(alloc);
> -        alloc = virResctrlAllocNew();
> -        if (!alloc)
> -            goto error;
> -
> -        if (virResctrlAllocParse(resctrl, alloc, schemata) < 0)
> -            goto error;
> -
>          virResctrlAllocSubtract(ret, alloc);
> +        virObjectUnref(alloc);
> +        alloc = NULL;
>      }
>      if (rv < 0)
>          goto error;

Michal