From: Mike Yuan Date: Mon, 26 May 2025 20:27:26 +0000 (+0200) Subject: cgroup-util: drop handcrafted cg_is_empty(), always check cgroup.events populated... X-Git-Tag: v258-rc1~483^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c3f900770d0cff0cdf89751b614397b5e226194a;p=thirdparty%2Fsystemd.git cgroup-util: drop handcrafted cg_is_empty(), always check cgroup.events populated field This effectively renames cg_is_empty_recursive() to cg_is_empty(). Note that all existing code calls the former and not the latter, hence with cgv1 support being dropped it's trivial to consult cgroup.events directly for populated state everywhere. Additionally, use more generic cg_get_keyed_attribute() helper rather than cg_read_event(). --- diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c index 1c752428924..02398d074ad 100644 --- a/src/basic/cgroup-util.c +++ b/src/basic/cgroup-util.c @@ -792,81 +792,25 @@ int cg_pidref_get_path(const char *controller, const PidRef *pidref, char **ret_ } int cg_is_empty(const char *controller, const char *path) { - _cleanup_fclose_ FILE *f = NULL; - pid_t pid; + _cleanup_free_ char *t = NULL; int r; - assert(path); - - r = cg_enumerate_processes(controller, path, &f); - if (r == -ENOENT) - return true; - if (r < 0) - return r; - - r = cg_read_pid(f, &pid, CGROUP_DONT_SKIP_UNMAPPED); - if (r < 0) - return r; - - return r == 0; -} - -int cg_is_empty_recursive(const char *controller, const char *path) { - int r; + /* Check if the cgroup hierarchy under 'path' is empty. On cgroup v2 it's exposed via the "populated" + * attribute of "cgroup.events". */ assert(path); /* The root cgroup is always populated */ - if (controller && empty_or_root(path)) + if (empty_or_root(path)) return false; - r = cg_unified_controller(controller); + r = cg_get_keyed_attribute(SYSTEMD_CGROUP_CONTROLLER, path, "cgroup.events", STRV_MAKE("populated"), &t); + if (r == -ENOENT) + return true; if (r < 0) return r; - if (r > 0) { - _cleanup_free_ char *t = NULL; - - /* On the unified hierarchy we can check empty state - * via the "populated" attribute of "cgroup.events". */ - - r = cg_read_event(controller, path, "populated", &t); - if (r == -ENOENT) - return true; - if (r < 0) - return r; - - return streq(t, "0"); - } else { - _cleanup_closedir_ DIR *d = NULL; - char *fn; - - r = cg_is_empty(controller, path); - if (r <= 0) - return r; - - r = cg_enumerate_subgroups(controller, path, &d); - if (r == -ENOENT) - return true; - if (r < 0) - return r; - while ((r = cg_read_subgroup(d, &fn)) > 0) { - _cleanup_free_ char *p = NULL; - - p = path_join(path, fn); - free(fn); - if (!p) - return -ENOMEM; - - r = cg_is_empty_recursive(controller, p); - if (r <= 0) - return r; - } - if (r < 0) - return r; - - return true; - } + return streq(t, "0"); } int cg_split_spec(const char *spec, char **ret_controller, char **ret_path) { diff --git a/src/basic/cgroup-util.h b/src/basic/cgroup-util.h index acb3427875e..9f02e65410a 100644 --- a/src/basic/cgroup-util.h +++ b/src/basic/cgroup-util.h @@ -233,7 +233,6 @@ int cg_get_xattr_bool(const char *path, const char *name); int cg_remove_xattr(const char *path, const char *name); int cg_is_empty(const char *controller, const char *path); -int cg_is_empty_recursive(const char *controller, const char *path); int cg_get_root_path(char **path); diff --git a/src/core/cgroup.c b/src/core/cgroup.c index 61ac5b6f449..abaffb22cde 100644 --- a/src/core/cgroup.c +++ b/src/core/cgroup.c @@ -2760,7 +2760,7 @@ int unit_cgroup_is_empty(Unit *u) { if (!crt->cgroup_path) return -EOWNERDEAD; - r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path); + r = cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path); if (r < 0) log_unit_debug_errno(u, r, "Failed to determine whether cgroup %s is empty: %m", empty_to_root(crt->cgroup_path)); return r; diff --git a/src/core/service.c b/src/core/service.c index d5874ce3938..c976ee63e4f 100644 --- a/src/core/service.c +++ b/src/core/service.c @@ -1976,7 +1976,7 @@ static int cgroup_good(Service *s) { if (!s->cgroup_runtime || !s->cgroup_runtime->cgroup_path) return 0; - r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_runtime->cgroup_path); + r = cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_runtime->cgroup_path); if (r < 0) return r; diff --git a/src/login/loginctl.c b/src/login/loginctl.c index 0f66c9dee66..1cbbd4ecf72 100644 --- a/src/login/loginctl.c +++ b/src/login/loginctl.c @@ -457,7 +457,7 @@ static int show_unit_cgroup( /* Fallback for older systemd versions where the GetUnitProcesses() call is not yet available */ - if (cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, cgroup) != 0 && leader <= 0) + if (cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, cgroup) != 0 && leader <= 0) return 0; show_cgroup_and_extra(SYSTEMD_CGROUP_CONTROLLER, cgroup, prefix, c, &leader, leader > 0, get_output_flags()); diff --git a/src/machine/machinectl.c b/src/machine/machinectl.c index d8dbaa09c53..32849529c95 100644 --- a/src/machine/machinectl.c +++ b/src/machine/machinectl.c @@ -436,7 +436,7 @@ static int show_unit_cgroup(sd_bus *bus, const char *unit, pid_t leader) { /* Fallback for older systemd versions where the GetUnitProcesses() call is not yet available */ - if (cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, cgroup) != 0 && leader <= 0) + if (cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, cgroup) != 0 && leader <= 0) return 0; show_cgroup_and_extra(SYSTEMD_CGROUP_CONTROLLER, cgroup, "\t\t ", c, &leader, leader > 0, get_output_flags()); diff --git a/src/shared/cgroup-show.c b/src/shared/cgroup-show.c index 258229daf3d..b95cecb3e66 100644 --- a/src/shared/cgroup-show.c +++ b/src/shared/cgroup-show.c @@ -251,7 +251,7 @@ int show_cgroup_by_path( if (!k) return -ENOMEM; - if (!(flags & OUTPUT_SHOW_ALL) && cg_is_empty_recursive(NULL, k) > 0) + if (!(flags & OUTPUT_SHOW_ALL) && cg_is_empty(NULL, k) > 0) continue; if (!shown_pids) { diff --git a/src/test/test-cgroup.c b/src/test/test-cgroup.c index 4d1bbd4b342..31f2d87800a 100644 --- a/src/test/test-cgroup.c +++ b/src/test/test-cgroup.c @@ -106,9 +106,7 @@ TEST(cg_create) { free(path); ASSERT_OK_POSITIVE(cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, test_a)); - ASSERT_OK_POSITIVE(cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, test_b)); - ASSERT_OK_POSITIVE(cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, test_a)); - ASSERT_OK_ZERO(cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, test_b)); + ASSERT_OK_ZERO(cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, test_b)); ASSERT_OK_ZERO(cg_kill_recursive(test_a, 0, 0, NULL, NULL, NULL)); ASSERT_OK_POSITIVE(cg_kill_recursive(test_b, 0, 0, NULL, NULL, NULL));