Commit 2bc12abc authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Add read_all_cgroups() and __cgroup_find() 



The read_all_cgroups() is to build a tree of cgroups in the system and
users can look up a cgroup using __cgroup_find().

Committer notes:

Had to do this to cover that #else block:

  -static inline u64 __read_cgroup_id(const char *path) { return -1ULL; }
  +static inline u64 __read_cgroup_id(const char *path __maybe_unused) { return -1ULL; }

Reviewed-by: default avatarIan Rogers <irogers@google.com>
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230906174903.346486-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 36019dff

tools/perf/util/cgroup.c

+53 −8
Original line number Diff line number Diff line
@@ -48,28 +48,36 @@ static int open_cgroup(const char *name) 
}



#ifdef HAVE_FILE_HANDLE

int read_cgroup_id(struct cgroup *cgrp)

static u64 __read_cgroup_id(const char *path)

{

	char path[PATH_MAX + 1];

	char mnt[PATH_MAX + 1];

	struct {

		struct file_handle fh;

		uint64_t cgroup_id;

	} handle;

	int mount_id;



	handle.fh.handle_bytes = sizeof(handle.cgroup_id);

	if (name_to_handle_at(AT_FDCWD, path, &handle.fh, &mount_id, 0) < 0)

		return -1ULL;



	return handle.cgroup_id;

}



int read_cgroup_id(struct cgroup *cgrp)

{

	char path[PATH_MAX + 1];

	char mnt[PATH_MAX + 1];



	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))

		return -1;



	scnprintf(path, PATH_MAX, "%s/%s", mnt, cgrp->name);



	handle.fh.handle_bytes = sizeof(handle.cgroup_id);

	if (name_to_handle_at(AT_FDCWD, path, &handle.fh, &mount_id, 0) < 0)

		return -1;



	cgrp->id = handle.cgroup_id;

	cgrp->id = __read_cgroup_id(path);

	return 0;

}

#else

static inline u64 __read_cgroup_id(const char *path __maybe_unused) { return -1ULL; }

#endif  /* HAVE_FILE_HANDLE */



#ifndef CGROUP2_SUPER_MAGIC
@@ -562,6 +570,11 @@ struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id, 
	return cgrp;

}



struct cgroup *__cgroup__find(struct rb_root *root, uint64_t id)

{

	return __cgroup__findnew(root, id, /*create=*/false, /*path=*/NULL);

}



struct cgroup *cgroup__find(struct perf_env *env, uint64_t id)

{

	struct cgroup *cgrp;
@@ -587,3 +600,35 @@ void perf_env__purge_cgroups(struct perf_env *env) 
	}

	up_write(&env->cgroups.lock);

}



void read_all_cgroups(struct rb_root *root)

{

	char mnt[PATH_MAX];

	struct cgroup_name *cn;

	int prefix_len;



	if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))

		return;



	/* cgroup_name will have a full path, skip the root directory */

	prefix_len = strlen(mnt);



	/* collect all cgroups in the cgroup_list */

	if (nftw(mnt, add_cgroup_name, 20, 0) < 0)

		return;



	list_for_each_entry(cn, &cgroup_list, list) {

		const char *name;

		u64 cgrp_id;



		/* cgroup_name might have a full path, skip the prefix */

		name = cn->name + prefix_len;

		if (name[0] == '\0')

			name = "/";



		cgrp_id = __read_cgroup_id(cn->name);

		__cgroup__findnew(root, cgrp_id, /*create=*/true, name);

	}



	release_cgroup_list();

}

tools/perf/util/cgroup.h

+4 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ int parse_cgroups(const struct option *opt, const char *str, int unset); 
struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id,

			       const char *path);

struct cgroup *cgroup__find(struct perf_env *env, uint64_t id);

struct cgroup *__cgroup__find(struct rb_root *root, uint64_t id);



void perf_env__purge_cgroups(struct perf_env *env);
@@ -49,6 +50,9 @@ static inline int read_cgroup_id(struct cgroup *cgrp __maybe_unused) 
}

#endif  /* HAVE_FILE_HANDLE */



/* read all cgroups in the system and save them in the rbtree */

void read_all_cgroups(struct rb_root *root);



int cgroup_is_v2(const char *subsys);



#endif /* __CGROUP_H__ */