Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 29 Jun 2021 23:35:17 -0700 | Subject | Re: [PATCH 2/4] perf tools: Add cgroup_is_v2() helper |
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Hi Ian,
On Tue, Jun 29, 2021 at 8:51 AM Ian Rogers <irogers@google.com> wrote: > > On Fri, Jun 25, 2021 at 12:18 AM Namhyung Kim <namhyung@kernel.org> wrote: > > > > The cgroup_is_v2() is to check if the given subsystem is mounted on > > cgroup v2 or not. It'll be used by BPF cgroup code later. > > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > > --- > > tools/perf/util/cgroup.c | 19 +++++++++++++++++++ > > tools/perf/util/cgroup.h | 2 ++ > > 2 files changed, 21 insertions(+) > > > > diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c > > index ef18c988c681..e819a4f30fc2 100644 > > --- a/tools/perf/util/cgroup.c > > +++ b/tools/perf/util/cgroup.c > > @@ -9,6 +9,7 @@ > > #include <linux/zalloc.h> > > #include <sys/types.h> > > #include <sys/stat.h> > > +#include <sys/statfs.h> > > #include <fcntl.h> > > #include <stdlib.h> > > #include <string.h> > > @@ -70,6 +71,24 @@ int read_cgroup_id(struct cgroup *cgrp) > > } > > #endif /* HAVE_FILE_HANDLE */ > > > > +#ifndef CGROUP2_SUPER_MAGIC > > +#define CGROUP2_SUPER_MAGIC 0x63677270 > > +#endif > > + > > +int cgroup_is_v2(const char *subsys) > > +{ > > + char mnt[PATH_MAX + 1]; > > + struct statfs stbuf; > > + > > + if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, subsys)) > > + return -1; > > + > > + if (statfs(mnt, &stbuf) < 0) > > + return -1; > > + > > + return (stbuf.f_type == CGROUP2_SUPER_MAGIC); > > +} > > + > > static struct cgroup *evlist__find_cgroup(struct evlist *evlist, const char *str) > > { > > struct evsel *counter; > > diff --git a/tools/perf/util/cgroup.h b/tools/perf/util/cgroup.h > > index 707adbe25123..1549ec2fd348 100644 > > --- a/tools/perf/util/cgroup.h > > +++ b/tools/perf/util/cgroup.h > > @@ -47,4 +47,6 @@ int read_cgroup_id(struct cgroup *cgrp) > > } > > #endif /* HAVE_FILE_HANDLE */ > > > > +int cgroup_is_v2(const char *subsys); > > + > > I think this is okay. It may make sense to have this in > tools/lib/api/fs/fs.h, for example fs__valid_mount is already checking > magic numbers. Perhaps we can avoid a statfs call, but it'd need some > reorganization of the fs.h code. > > Acked-by: Ian Rogers <irogers@google.com>
Thanks for your review!
Actually I'm ok with moving it to tools/lib. Will do it in the next spin, if it needs one. :)
Thanks, Namhyung
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