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

[Pavel Hrdina]

On Thu, Oct 04, 2018 at 01:18:16PM +0200, Michal Privoznik wrote:
> 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.

Since I was considering it I'll fix it before pushing, thanks.

> 
> > +
> > +    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
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