[libvirt] [PATCH 10/53] vircgroup: introduce virCgroupV2DetectControllers

[Michal Privoznik]

On 10/02/2018 10:43 AM, Pavel Hrdina wrote:
> Cgroup v2 has only single mount point for all controllers.  The list
> of controllers is stored in cgroup.controllers file, name of controllers
> are separated by space.
> 
> In cgroup v2 there is no cpuacct controller, the cpu.stat file always
> exists with usage stats.
> 
> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> ---
>  src/util/vircgroupv2.c | 67 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
> 
> diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c
> index d4e0366780..3200338fe3 100644
> --- a/src/util/vircgroupv2.c
> +++ b/src/util/vircgroupv2.c
> @@ -32,6 +32,7 @@
>  #include "vircgroup.h"
>  #include "vircgroupbackend.h"
>  #include "vircgroupv2.h"
> +#include "virerror.h"
>  #include "virfile.h"
>  #include "virlog.h"
>  #include "virstring.h"
> @@ -232,6 +233,71 @@ virCgroupV2StealPlacement(virCgroupPtr group)
>  }
>  
>  
> +static int
> +virCgroupV2ParseControllersFile(virCgroupPtr group)
> +{
> +    int rc;
> +    VIR_AUTOFREE(char *) contStr = NULL;
> +    VIR_AUTOFREE(char *) contFile = NULL;
> +    char **contList = NULL;
> +    char **tmp;
> +
> +    if (virAsprintf(&contFile, "%s/cgroup.controllers",
> +                    group->unified.mountPoint) < 0)
> +        return -1;
> +
> +    rc = virFileReadAll(contFile, 1024 * 1024, &contStr);
> +    if (rc < 0) {
> +        virReportSystemError(errno, _("Unable to read from '%s'"), contFile);
> +        return -1;
> +    }
> +
> +    virTrimSpaces(contStr, NULL);
> +
> +    contList = virStringSplit(contStr, " ", 20);
> +    if (!contList)
> +        return -1;
> +
> +    tmp = contList;
> +
> +    while (*tmp) {
> +        int type = virCgroupV2ControllerTypeFromString(*tmp);
> +
> +        if (type >= 0)
> +            group->unified.controllers |= 1 << type;
> +
> +        tmp++;
> +    }
> +
> +    virStringListFree(contList);
> +
> +    return 0;
> +}
> +
> +
> +static int
> +virCgroupV2DetectControllers(virCgroupPtr group,
> +                             int controllers)
> +{
> +    size_t i;
> +
> +    if (virCgroupV2ParseControllersFile(group) < 0)
> +        return -1;
> +
> +    group->unified.controllers |= 1 << VIR_CGROUP_CONTROLLER_CPUACCT;

I'd put a comment here describing what you do in the commit message.
Sure I can go to commit message if I want to, but a comment is more handy.

> +
> +    for (i = 0; i < VIR_CGROUP_CONTROLLER_LAST; i++)
> +        VIR_DEBUG("Controller '%s' present=%s",
> +                  virCgroupV2ControllerTypeToString(i),
> +                  (group->unified.controllers & 1 << i) ? "yes" : "no");
> +
> +    if (controllers >= 0)
> +        return controllers & group->unified.controllers;
> +    else
> +        return group->unified.controllers;
> +}
> +
> +
>  virCgroupBackend virCgroupV2Backend = {
>      .type = VIR_CGROUP_BACKEND_TYPE_V2,
>  
> @@ -243,6 +309,7 @@ virCgroupBackend virCgroupV2Backend = {
>      .detectPlacement = virCgroupV2DetectPlacement,
>      .validatePlacement = virCgroupV2ValidatePlacement,
>      .stealPlacement = virCgroupV2StealPlacement,
> +    .detectControllers = virCgroupV2DetectControllers,
>  };
>  
>  
> 

ACK

Michal