Re: [libvirt] [PATCH 42/53] vircgroup: add support for hybrid configuration

On 10/02/2018 10:44 AM, Pavel Hrdina wrote: > This enables to use both cgroup v1 and v2 at the same time together > with libvirt. It is supported by kernel and there is valid use-case, > not all controllers are implemented in cgroup v2 so there might be > configurations where administrator would enable these missing > controllers in cgroup v1. > > Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; > --- > src/util/vircgroup.c | 351 ++++++++++++++++++++++++++---------- > src/util/vircgroupbackend.c | 20 ++ > src/util/vircgroupbackend.h | 16 +- > src/util/vircgrouppriv.h | 2 +- > 4 files changed, 291 insertions(+), 98 deletions(-) > > diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c > index dc249bfe33..4aec5f1bcf 100644 > --- a/src/util/vircgroup.c > +++ b/src/util/vircgroup.c > @@ -228,6 +228,7 @@ virCgroupDetectMounts(virCgroupPtr group) > struct mntent entry; > char buf[CGROUP_MAX_VAL]; > int ret = -1; > + size_t i; > > mounts = fopen("/proc/mounts", "r"); > if (mounts == NULL) { > @@ -236,11 +237,14 @@ virCgroupDetectMounts(virCgroupPtr group) > } > > while (getmntent_r(mounts, &entry, buf, sizeof(buf)) != NULL) { > - if (group->backend->detectMounts(group, > - entry.mnt_type, > - entry.mnt_opts, > - entry.mnt_dir) < 0) { > - goto cleanup; > + for (i = 0; i < VIR_CGROUP_BACKEND_TYPE_LAST; i++) { > + if (group->backends[i] && > + group->backends[i]->detectMounts(group, > + entry.mnt_type, > + entry.mnt_opts, > + entry.mnt_dir) < 0) { > + goto cleanup; > + } > } > } > > @@ -303,6 +307,7 @@ virCgroupDetectPlacement(virCgroupPtr group, > } > > while (fgets(line, sizeof(line), mapping) != NULL) { > + size_t i; > char *controllers = strchr(line, ':'); > char *selfpath = controllers ? strchr(controllers + 1, ':') : NULL; > char *nl = selfpath ? strchr(selfpath, '\n') : NULL; > @@ -317,9 +322,12 @@ virCgroupDetectPlacement(virCgroupPtr group, > controllers++; > selfpath++; > > - if (group->backend->detectPlacement(group, path, controllers, > - selfpath) < 0) { > - goto cleanup; > + for (i = 0; i < VIR_CGROUP_BACKEND_TYPE_LAST; i++) { > + if (group->backends[i] && > + group->backends[i]->detectPlacement(group, path, controllers, > + selfpath) < 0) { > + goto cleanup; > + } So a loop like this appears all over the patch: for (i = 0; i < VIR_CGROUP_BACKEND_TYPE_LAST; i++) { if (group->backends[i] && group->backends[i]->cb(); } I wonder if we should have wrappers around these chunks of code. But that could be saved as a follow up patch.

> } > } > > @@ -338,8 +346,9 @@ virCgroupDetect(virCgroupPtr group, > const char *path, > virCgroupPtr parent) > { > - int rc; > size_t i; > + bool backendAvailable = false; > + int controllersAvailable = 0; > virCgroupBackendPtr *backends = virCgroupBackendGetAll(); > > VIR_DEBUG("group=%p controllers=%d path=%s parent=%p", > @@ -350,31 +359,40 @@ virCgroupDetect(virCgroupPtr group, > > for (i = 0; i < VIR_CGROUP_BACKEND_TYPE_LAST; i++) { > if (backends[i] && backends[i]->available()) { > - group->backend = backends[i]; > - break; > + group->backends[i] = backends[i]; > + backendAvailable = true; No need to remove the 'break'.