From bf47300b186facc8ae66a0e2aa89073565f82bb3 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Sat, 11 Nov 2023 09:00:33 +0000 Subject: [PATCH] selftests/bpf: Add a new cgroup helper get_cgroup_hierarchy_id() A new cgroup helper function, get_cgroup1_hierarchy_id(), has been introduced to obtain the ID of a cgroup1 hierarchy based on the provided cgroup name. This cgroup name can be obtained from the /proc/self/cgroup file. Signed-off-by: Yafang Shao Link: https://lore.kernel.org/r/20231111090034.4248-6-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/cgroup_helpers.c | 52 ++++++++++++++++++++ tools/testing/selftests/bpf/cgroup_helpers.h | 1 + 2 files changed, 53 insertions(+) diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c index 63bfa72185be2c..5aa133bf368806 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.c +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -637,3 +637,55 @@ unsigned long long get_classid_cgroup_id(void) format_classid_path(cgroup_workdir); return get_cgroup_id_from_path(cgroup_workdir); } + +/** + * get_cgroup1_hierarchy_id - Retrieves the ID of a cgroup1 hierarchy from the cgroup1 subsys name. + * @subsys_name: The cgroup1 subsys name, which can be retrieved from /proc/self/cgroup. It can be + * a named cgroup like "name=systemd", a controller name like "net_cls", or multi-contollers like + * "net_cls,net_prio". + */ +int get_cgroup1_hierarchy_id(const char *subsys_name) +{ + char *c, *c2, *c3, *c4; + bool found = false; + char line[1024]; + FILE *file; + int i, id; + + if (!subsys_name) + return -1; + + file = fopen("/proc/self/cgroup", "r"); + if (!file) { + log_err("fopen /proc/self/cgroup"); + return -1; + } + + while (fgets(line, 1024, file)) { + i = 0; + for (c = strtok_r(line, ":", &c2); c && i < 2; c = strtok_r(NULL, ":", &c2)) { + if (i == 0) { + id = strtol(c, NULL, 10); + } else if (i == 1) { + if (!strcmp(c, subsys_name)) { + found = true; + break; + } + + /* Multiple subsystems may share one single mount point */ + for (c3 = strtok_r(c, ",", &c4); c3; + c3 = strtok_r(NULL, ",", &c4)) { + if (!strcmp(c, subsys_name)) { + found = true; + break; + } + } + } + i++; + } + if (found) + break; + } + fclose(file); + return found ? id : -1; +} diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h index e71da4ef031bed..ee053641c0267a 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.h +++ b/tools/testing/selftests/bpf/cgroup_helpers.h @@ -20,6 +20,7 @@ int get_root_cgroup(void); int create_and_get_cgroup(const char *relative_path); void remove_cgroup(const char *relative_path); unsigned long long get_cgroup_id(const char *relative_path); +int get_cgroup1_hierarchy_id(const char *subsys_name); int join_cgroup(const char *relative_path); int join_root_cgroup(void);