Prep v234: Apply missing upstream fixes in src/basic (1/6)

[elogind.git] / src / basic / cgroup-util.c

diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index 323720caef49797a6cd33c5f103f4f8a488846c5..315c449656aa073ce6aadad84e0506b82e246a6f 100644 (file)
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -55,6 +55,7 @@
 #include "stdio-util.h"
 #include "string-table.h"
 #include "string-util.h"
 #include "stdio-util.h"
 #include "string-table.h"
 #include "string-util.h"

+#include "strv.h"

 #include "unit-name.h"
 #include "user-util.h"
 
 #include "unit-name.h"
 #include "user-util.h"
 


@@ -210,7 +211,13 @@ int cg_rmdir(const char *controller, const char *path) {
         if (r < 0 && errno != ENOENT)
                 return -errno;
 
         if (r < 0 && errno != ENOENT)
                 return -errno;
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        r = cg_hybrid_unified();
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return 0;
+
+        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 r = cg_rmdir(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path);
                 if (r < 0)
                         log_warning_errno(r, "Failed to remove compat systemd cgroup %s: %m", path);
                 r = cg_rmdir(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path);
                 if (r < 0)
                         log_warning_errno(r, "Failed to remove compat systemd cgroup %s: %m", path);


@@ -555,7 +562,7 @@ static const char *controller_to_dirname(const char *controller) {
          * hierarchies, if it is specified. */
 
         if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {
          * hierarchies, if it is specified. */
 
         if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

-                if (cg_hybrid_unified())
+                if (cg_hybrid_unified() > 0)

                         controller = SYSTEMD_CGROUP_CONTROLLER_HYBRID;
                 else
                         controller = SYSTEMD_CGROUP_CONTROLLER_LEGACY;
                         controller = SYSTEMD_CGROUP_CONTROLLER_HYBRID;
                 else
                         controller = SYSTEMD_CGROUP_CONTROLLER_LEGACY;


@@ -642,7 +649,10 @@ int cg_get_path(const char *controller, const char *path, const char *suffix, ch
         if (!cg_controller_is_valid(controller))
                 return -EINVAL;
 
         if (!cg_controller_is_valid(controller))
                 return -EINVAL;
 

-        if (cg_all_unified())
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r > 0)

                 r = join_path_unified(path, suffix, fs);
         else
                 r = join_path_legacy(controller, path, suffix, fs);
                 r = join_path_unified(path, suffix, fs);
         else
                 r = join_path_legacy(controller, path, suffix, fs);


@@ -654,6 +664,7 @@ int cg_get_path(const char *controller, const char *path, const char *suffix, ch
 }
 
 static int controller_is_accessible(const char *controller) {
 }
 
 static int controller_is_accessible(const char *controller) {

+        int r;

 
         assert(controller);
 
 
         assert(controller);
 


@@ -665,7 +676,10 @@ static int controller_is_accessible(const char *controller) {
         if (!cg_controller_is_valid(controller))
                 return -EINVAL;
 
         if (!cg_controller_is_valid(controller))
                 return -EINVAL;
 

-        if (cg_all_unified()) {
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r > 0) {

                 /* We don't support named hierarchies if we are using
                  * the unified hierarchy. */
 
                 /* We don't support named hierarchies if we are using
                  * the unified hierarchy. */
 


@@ -742,7 +756,10 @@ int cg_trim(const char *controller, const char *path, bool delete_root) {
                         return -errno;
         }
 
                         return -errno;
         }
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        q = cg_hybrid_unified();
+        if (q < 0)
+                return q;
+        if (q > 0 && streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 q = cg_trim(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, delete_root);
                 if (q < 0)
                         log_warning_errno(q, "Failed to trim compat systemd cgroup %s: %m", path);
                 q = cg_trim(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, delete_root);
                 if (q < 0)
                         log_warning_errno(q, "Failed to trim compat systemd cgroup %s: %m", path);


@@ -771,7 +788,11 @@ int cg_create(const char *controller, const char *path) {
                 return -errno;
         }
 
                 return -errno;
         }
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        r = cg_hybrid_unified();
+        if (r < 0)
+                return r;
+
+        if (r > 0 && streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 r = cg_create(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path);
                 if (r < 0)
                         log_warning_errno(r, "Failed to create compat systemd cgroup %s: %m", path);
                 r = cg_create(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path);
                 if (r < 0)
                         log_warning_errno(r, "Failed to create compat systemd cgroup %s: %m", path);


@@ -818,10 +839,14 @@ int cg_attach(const char *controller, const char *path, pid_t pid) {
         if (r < 0)
                 return r;
 
         if (r < 0)
                 return r;
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        r = cg_hybrid_unified();
+        if (r < 0)
+                return r;
+
+        if (r > 0 && streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 r = cg_attach(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, pid);
                 if (r < 0)
                 r = cg_attach(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, pid);
                 if (r < 0)

-                        log_warning_errno(r, "Failed to attach %d to compat systemd cgroup %s: %m", pid, path);
+                        log_warning_errno(r, "Failed to attach "PID_FMT" to compat systemd cgroup %s: %m", pid, path);

         }
 
         return 0;
         }
 
         return 0;


@@ -878,7 +903,10 @@ int cg_set_group_access(
         if (r < 0)
                 return r;
 
         if (r < 0)
                 return r;
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        r = cg_hybrid_unified();
+        if (r < 0)
+                return r;
+        if (r > 0 && streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 r = cg_set_group_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid);
                 if (r < 0)
                         log_warning_errno(r, "Failed to set group access on compat systemd cgroup %s: %m", path);
                 r = cg_set_group_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid);
                 if (r < 0)
                         log_warning_errno(r, "Failed to set group access on compat systemd cgroup %s: %m", path);


@@ -913,14 +941,20 @@ int cg_set_task_access(
         if (r < 0)
                 return r;
 
         if (r < 0)
                 return r;
 

-        if (!cg_unified(controller)) {
+        r = cg_unified_controller(controller);
+        if (r < 0)
+                return r;
+        if (r == 0) {

                 /* Compatibility, Always keep values for "tasks" in sync with
                  * "cgroup.procs" */
                 if (cg_get_path(controller, path, "tasks", &procs) >= 0)
                         (void) chmod_and_chown(procs, mode, uid, gid);
         }
 
                 /* Compatibility, Always keep values for "tasks" in sync with
                  * "cgroup.procs" */
                 if (cg_get_path(controller, path, "tasks", &procs) >= 0)
                         (void) chmod_and_chown(procs, mode, uid, gid);
         }
 

-        if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) {
+        r = cg_hybrid_unified();
+        if (r < 0)
+                return r;
+        if (r > 0 && streq(controller, SYSTEMD_CGROUP_CONTROLLER)) {

                 r = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid);
                 if (r < 0)
                         log_warning_errno(r, "Failed to set task access on compat systemd cgroup %s: %m", path);
                 r = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid);
                 if (r < 0)
                         log_warning_errno(r, "Failed to set task access on compat systemd cgroup %s: %m", path);


@@ -970,9 +1004,9 @@ int cg_get_xattr(const char *controller, const char *path, const char *name, voi
 int cg_pid_get_path(const char *controller, pid_t pid, char **path) {
         _cleanup_fclose_ FILE *f = NULL;
         char line[LINE_MAX];
 int cg_pid_get_path(const char *controller, pid_t pid, char **path) {
         _cleanup_fclose_ FILE *f = NULL;
         char line[LINE_MAX];

-        const char *fs, *controller_str;
+        const char *fs, *controller_str = NULL;

         size_t cs = 0;
         size_t cs = 0;

-        bool unified;
+        int unified;

 
         assert(path);
         assert(pid >= 0);
 
         assert(path);
         assert(pid >= 0);


@@ -983,8 +1017,10 @@ int cg_pid_get_path(const char *controller, pid_t pid, char **path) {
         } else
                 controller = SYSTEMD_CGROUP_CONTROLLER;
 
         } else
                 controller = SYSTEMD_CGROUP_CONTROLLER;
 

-        unified = cg_unified(controller);
-        if (!unified) {
+        unified = cg_unified_controller(controller);
+        if (unified < 0)
+                return unified;
+        if (unified == 0) {

                 if (streq(controller, SYSTEMD_CGROUP_CONTROLLER))
                         controller_str = SYSTEMD_CGROUP_CONTROLLER_LEGACY;
                 else
                 if (streq(controller, SYSTEMD_CGROUP_CONTROLLER))
                         controller_str = SYSTEMD_CGROUP_CONTROLLER_LEGACY;
                 else


@@ -1059,7 +1095,10 @@ int cg_install_release_agent(const char *controller, const char *agent) {
 
         assert(agent);
 
 
         assert(agent);
 

-        if (cg_unified(controller)) /* doesn't apply to unified hierarchy */
+        r = cg_unified_controller(controller);
+        if (r < 0)
+                return r;
+        if (r > 0) /* doesn't apply to unified hierarchy */

                 return -EOPNOTSUPP;
 
         r = cg_get_path(controller, NULL, "release_agent", &fs);
                 return -EOPNOTSUPP;
 
         r = cg_get_path(controller, NULL, "release_agent", &fs);


@@ -1107,7 +1146,10 @@ int cg_uninstall_release_agent(const char *controller) {
         _cleanup_free_ char *fs = NULL;
         int r;
 
         _cleanup_free_ char *fs = NULL;
         int r;
 

-        if (cg_unified(controller)) /* Doesn't apply to unified hierarchy */
+        r = cg_unified_controller(controller);
+        if (r < 0)
+                return r;
+        if (r > 0) /* Doesn't apply to unified hierarchy */

                 return -EOPNOTSUPP;
 
         r = cg_get_path(controller, NULL, "notify_on_release", &fs);
                 return -EOPNOTSUPP;
 
         r = cg_get_path(controller, NULL, "notify_on_release", &fs);


@@ -1160,7 +1202,10 @@ int cg_is_empty_recursive(const char *controller, const char *path) {
         if (controller && (isempty(path) || path_equal(path, "/")))
                 return false;
 
         if (controller && (isempty(path) || path_equal(path, "/")))
                 return false;
 

-        if (cg_unified(controller)) {
+        r = cg_unified_controller(controller);
+        if (r < 0)
+                return r;
+        if (r > 0) {

                 _cleanup_free_ char *t = NULL;
 
                 /* On the unified hierarchy we can check empty state
                 _cleanup_free_ char *t = NULL;
 
                 /* On the unified hierarchy we can check empty state


@@ -2087,7 +2132,10 @@ int cg_create_everywhere(CGroupMask supported, CGroupMask mask, const char *path
                 return r;
 
         /* If we are in the unified hierarchy, we are done now */
                 return r;
 
         /* If we are in the unified hierarchy, we are done now */

-        if (cg_all_unified())
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r > 0)

                 return 0;
 
         /* Otherwise, do the same in the other hierarchies */
                 return 0;
 
         /* Otherwise, do the same in the other hierarchies */


@@ -2114,7 +2162,10 @@ int cg_attach_everywhere(CGroupMask supported, const char *path, pid_t pid, cg_m
         if (r < 0)
                 return r;
 
         if (r < 0)
                 return r;
 

-        if (cg_all_unified())
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r > 0)

                 return 0;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
                 return 0;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {


@@ -2155,7 +2206,7 @@ int cg_attach_many_everywhere(CGroupMask supported, const char *path, Set* pids,
 
 int cg_migrate_everywhere(CGroupMask supported, const char *from, const char *to, cg_migrate_callback_t to_callback, void *userdata) {
         CGroupController c;
 
 int cg_migrate_everywhere(CGroupMask supported, const char *from, const char *to, cg_migrate_callback_t to_callback, void *userdata) {
         CGroupController c;

-        int r = 0;
+        int r = 0, q;

 
         if (!path_equal(from, to))  {
                 r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, from, SYSTEMD_CGROUP_CONTROLLER, to, CGROUP_REMOVE);
 
         if (!path_equal(from, to))  {
                 r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, from, SYSTEMD_CGROUP_CONTROLLER, to, CGROUP_REMOVE);


@@ -2163,7 +2214,10 @@ int cg_migrate_everywhere(CGroupMask supported, const char *from, const char *to
                         return r;
         }
 
                         return r;
         }
 

-        if (cg_all_unified())
+        q = cg_all_unified();
+        if (q < 0)
+                return q;
+        if (q > 0)

                 return r;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
                 return r;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {


@@ -2187,13 +2241,16 @@ int cg_migrate_everywhere(CGroupMask supported, const char *from, const char *to
 
 int cg_trim_everywhere(CGroupMask supported, const char *path, bool delete_root) {
         CGroupController c;
 
 int cg_trim_everywhere(CGroupMask supported, const char *path, bool delete_root) {
         CGroupController c;

-        int r;
+        int r, q;

 
         r = cg_trim(SYSTEMD_CGROUP_CONTROLLER, path, delete_root);
         if (r < 0)
                 return r;
 
 
         r = cg_trim(SYSTEMD_CGROUP_CONTROLLER, path, delete_root);
         if (r < 0)
                 return r;
 

-        if (cg_all_unified())
+        q = cg_all_unified();
+        if (q < 0)
+                return q;
+        if (q > 0)

                 return r;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
                 return r;
 
         for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {


@@ -2209,6 +2266,60 @@ int cg_trim_everywhere(CGroupMask supported, const char *path, bool delete_root)
 }
 #endif // 0
 
 }
 #endif // 0
 

+int cg_mask_to_string(CGroupMask mask, char **ret) {
+        const char *controllers[_CGROUP_CONTROLLER_MAX + 1];
+        CGroupController c;
+        int i = 0;
+        char *s;
+
+        assert(ret);
+
+        if (mask == 0) {
+                *ret = NULL;
+                return 0;
+        }
+
+        for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
+
+                if (!(mask & CGROUP_CONTROLLER_TO_MASK(c)))
+                        continue;
+
+                controllers[i++] = cgroup_controller_to_string(c);
+                controllers[i] = NULL;
+        }
+
+        s = strv_join((char **)controllers, NULL);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
+}
+
+int cg_mask_from_string(const char *value, CGroupMask *mask) {
+        assert(mask);
+        assert(value);
+
+        for (;;) {
+                _cleanup_free_ char *n = NULL;
+                CGroupController v;
+                int r;
+
+                r = extract_first_word(&value, &n, NULL, 0);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        break;
+
+                v = cgroup_controller_from_string(n);
+                if (v < 0)
+                        continue;
+
+                *mask |= CGROUP_CONTROLLER_TO_MASK(v);
+        }
+        return 0;
+}
+

 int cg_mask_supported(CGroupMask *ret) {
         CGroupMask mask = 0;
         int r;
 int cg_mask_supported(CGroupMask *ret) {
         CGroupMask mask = 0;
         int r;


@@ -2217,9 +2328,11 @@ int cg_mask_supported(CGroupMask *ret) {
          * includes controllers we can make sense of and that are
          * actually accessible. */
 
          * includes controllers we can make sense of and that are
          * actually accessible. */
 

-        if (cg_all_unified()) {
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r > 0) {

                 _cleanup_free_ char *root = NULL, *controllers = NULL, *path = NULL;
                 _cleanup_free_ char *root = NULL, *controllers = NULL, *path = NULL;

-                const char *c;

 
                 /* In the unified hierarchy we can read the supported
                  * and accessible controllers from a the top-level
 
                 /* In the unified hierarchy we can read the supported
                  * and accessible controllers from a the top-level


@@ -2237,23 +2350,9 @@ int cg_mask_supported(CGroupMask *ret) {
                 if (r < 0)
                         return r;
 
                 if (r < 0)
                         return r;
 

-                c = controllers;
-                for (;;) {
-                        _cleanup_free_ char *n = NULL;
-                        CGroupController v;
-
-                        r = extract_first_word(&c, &n, NULL, 0);
-                        if (r < 0)
-                                return r;
-                        if (r == 0)
-                                break;
-
-                        v = cgroup_controller_from_string(n);
-                        if (v < 0)
-                                continue;
-
-                        mask |= CGROUP_CONTROLLER_TO_MASK(v);
-                }
+                r = cg_mask_from_string(controllers, &mask);
+                if (r < 0)
+                        return r;

 
                 /* Currently, we support the cpu, memory, io and pids
                  * controller in the unified hierarchy, mask
 
                 /* Currently, we support the cpu, memory, io and pids
                  * controller in the unified hierarchy, mask


@@ -2339,7 +2438,18 @@ int cg_kernel_controllers(Set *controllers) {
 
 static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN;
 
 
 static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN;
 

-static int cg_update_unified(void) {
+/* The hybrid mode was initially implemented in v232 and simply mounted cgroup v2 on /sys/fs/cgroup/systemd.  This
+ * unfortunately broke other tools (such as docker) which expected the v1 "name=systemd" hierarchy on
+ * /sys/fs/cgroup/systemd.  From v233 and on, the hybrid mode mountnbs v2 on /sys/fs/cgroup/unified and maintains
+ * "name=systemd" hierarchy on /sys/fs/cgroup/systemd for compatibility with other tools.
+ *
+ * To keep live upgrade working, we detect and support v232 layout.  When v232 layout is detected, to keep cgroup v2
+ * process management but disable the compat dual layout, we return %true on
+ * cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) and %false on cg_hybrid_unified().
+ */
+static thread_local bool unified_systemd_v232;
+
+static int cg_unified_update(void) {

 
         struct statfs fs;
 
 
         struct statfs fs;
 


@@ -2359,9 +2469,14 @@ static int cg_update_unified(void) {
                 unified_cache = CGROUP_UNIFIED_ALL;
         else if (F_TYPE_EQUAL(fs.f_type, TMPFS_MAGIC)) {
                 if (statfs("/sys/fs/cgroup/unified/", &fs) == 0 &&
                 unified_cache = CGROUP_UNIFIED_ALL;
         else if (F_TYPE_EQUAL(fs.f_type, TMPFS_MAGIC)) {
                 if (statfs("/sys/fs/cgroup/unified/", &fs) == 0 &&

-                    F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC))
+                    F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) {
+                        unified_cache = CGROUP_UNIFIED_SYSTEMD;
+                        unified_systemd_v232 = false;
+                } else if (statfs("/sys/fs/cgroup/systemd/", &fs) == 0 &&
+                           F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) {

                         unified_cache = CGROUP_UNIFIED_SYSTEMD;
                         unified_cache = CGROUP_UNIFIED_SYSTEMD;

-                else {
+                        unified_systemd_v232 = true;
+                } else {

                         if (statfs("/sys/fs/cgroup/systemd/", &fs) < 0)
                                 return -errno;
                         if (!F_TYPE_EQUAL(fs.f_type, CGROUP_SUPER_MAGIC))
                         if (statfs("/sys/fs/cgroup/systemd/", &fs) < 0)
                                 return -errno;
                         if (!F_TYPE_EQUAL(fs.f_type, CGROUP_SUPER_MAGIC))


@@ -2382,35 +2497,49 @@ static int cg_update_unified(void) {
         return 0;
 }
 
         return 0;
 }
 

-bool cg_unified(const char *controller) {
+int cg_unified_controller(const char *controller) {
+        int r;

 
 

-        assert(cg_update_unified() >= 0);
+        r = cg_unified_update();
+        if (r < 0)
+                return r;

 
 

-        if (streq_ptr(controller, SYSTEMD_CGROUP_CONTROLLER))
-                return unified_cache >= CGROUP_UNIFIED_SYSTEMD;
-        else
-                return unified_cache >= CGROUP_UNIFIED_ALL;
+        if (unified_cache == CGROUP_UNIFIED_NONE)
+                return false;
+
+        if (unified_cache >= CGROUP_UNIFIED_ALL)
+                return true;
+
+        return streq_ptr(controller, SYSTEMD_CGROUP_CONTROLLER);

 }
 
 }
 

-bool cg_all_unified(void) {
+int cg_all_unified(void) {
+        int r;

 
 

-        return cg_unified(NULL);
+        r = cg_unified_update();
+        if (r < 0)
+                return r;
+
+        return unified_cache >= CGROUP_UNIFIED_ALL;

 }
 
 }
 

-#if 0 /// UNNEEDED by elogind
-bool cg_hybrid_unified(void) {
+int cg_hybrid_unified(void) {
+        int r;

 
 

-        assert(cg_update_unified() >= 0);
+        r = cg_unified_update();
+        if (r < 0)
+                return r;

 
 

-        return unified_cache == CGROUP_UNIFIED_SYSTEMD;
+        return unified_cache == CGROUP_UNIFIED_SYSTEMD && !unified_systemd_v232;

 }
 
 int cg_unified_flush(void) {
         unified_cache = CGROUP_UNIFIED_UNKNOWN;
 
 }
 
 int cg_unified_flush(void) {
         unified_cache = CGROUP_UNIFIED_UNKNOWN;
 

-        return cg_update_unified();
+        return cg_unified_update();

 }
 
 }
 

+#if 0 /// UNNEEDED by elogind

 int cg_enable_everywhere(CGroupMask supported, CGroupMask mask, const char *p) {
         _cleanup_free_ char *fs = NULL;
         CGroupController c;
 int cg_enable_everywhere(CGroupMask supported, CGroupMask mask, const char *p) {
         _cleanup_free_ char *fs = NULL;
         CGroupController c;


@@ -2421,7 +2550,10 @@ int cg_enable_everywhere(CGroupMask supported, CGroupMask mask, const char *p) {
         if (supported == 0)
                 return 0;
 
         if (supported == 0)
                 return 0;
 

-        if (!cg_all_unified()) /* on the legacy hiearchy there's no joining of controllers defined */
+        r = cg_all_unified();
+        if (r < 0)
+                return r;
+        if (r == 0) /* on the legacy hiearchy there's no joining of controllers defined */

                 return 0;
 
         r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, p, "cgroup.subtree_control", &fs);
                 return 0;
 
         r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, p, "cgroup.subtree_control", &fs);


@@ -2455,60 +2587,77 @@ bool cg_is_unified_wanted(void) {
         static thread_local int wanted = -1;
         int r;
         bool b;
         static thread_local int wanted = -1;
         int r;
         bool b;

+        const bool is_default = DEFAULT_HIERARCHY == CGROUP_UNIFIED_ALL;
+
+        /* If we have a cached value, return that. */
+        if (wanted >= 0)
+                return wanted;

 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */
         if (cg_unified_flush() >= 0)
 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */
         if (cg_unified_flush() >= 0)

-                return cg_all_unified();
-
-        /* Otherwise, let's see what the kernel command line has to
-         * say. Since checking that is expensive, let's cache the
-         * result. */
-        if (wanted >= 0)
-                return wanted;
+                return (wanted = unified_cache >= CGROUP_UNIFIED_ALL);

 
 

+        /* Otherwise, let's see what the kernel command line has to say.
+         * Since checking is expensive, cache a non-error result. */

         r = proc_cmdline_get_bool("systemd.unified_cgroup_hierarchy", &b);
         r = proc_cmdline_get_bool("systemd.unified_cgroup_hierarchy", &b);

-        if (r < 0)
-                return false;

 
 

-        return (wanted = r > 0 ? b : false);
+        return (wanted = r > 0 ? b : is_default);

 }
 
 bool cg_is_legacy_wanted(void) {
 }
 
 bool cg_is_legacy_wanted(void) {

-        return !cg_is_unified_wanted();
+        static thread_local int wanted = -1;
+
+        /* If we have a cached value, return that. */
+        if (wanted >= 0)
+                return wanted;
+
+        /* Check if we have cgroups2 already mounted. */
+        if (cg_unified_flush() >= 0 &&
+            unified_cache == CGROUP_UNIFIED_ALL)
+                return (wanted = false);
+
+        /* Otherwise, assume that at least partial legacy is wanted,
+         * since cgroups2 should already be mounted at this point. */
+        return (wanted = true);

 }
 
 }
 

-bool cg_is_unified_systemd_controller_wanted(void) {
+bool cg_is_hybrid_wanted(void) {

         static thread_local int wanted = -1;
         int r;
         bool b;
         static thread_local int wanted = -1;
         int r;
         bool b;

+        const bool is_default = DEFAULT_HIERARCHY >= CGROUP_UNIFIED_SYSTEMD;
+        /* We default to true if the default is "hybrid", obviously,
+         * but also when the default is "unified", because if we get
+         * called, it means that unified hierarchy was not mounted. */

 
 

-        /* If the unified hierarchy is requested in full, no need to
-         * bother with this. */
-        if (cg_is_unified_wanted())
-                return 0;
+        /* If we have a cached value, return that. */
+        if (wanted >= 0)
+                return wanted;

 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */
 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */

-        if (cg_unified_flush() >= 0)
-                return cg_unified(SYSTEMD_CGROUP_CONTROLLER);
-
-        /* Otherwise, let's see what the kernel command line has to
-         * say. Since checking that is expensive, let's cache the
-         * result. */
-        if (wanted >= 0)
-                return wanted;
+        if (cg_unified_flush() >= 0 &&
+            unified_cache == CGROUP_UNIFIED_ALL)
+                return (wanted = false);

 
 

+        /* Otherwise, let's see what the kernel command line has to say.
+         * Since checking is expensive, cache a non-error result. */

         r = proc_cmdline_get_bool("systemd.legacy_systemd_cgroup_controller", &b);
         r = proc_cmdline_get_bool("systemd.legacy_systemd_cgroup_controller", &b);

-        if (r < 0)
-                return false;

 
 

+        /* The meaning of the kernel option is reversed wrt. to the return value
+         * of this function, hence the negation. */
+        return (wanted = r > 0 ? !b : is_default);
+}

 #else
 #else

+bool cg_is_unified_wanted(void) {
+        return false;
+}

 bool cg_is_legacy_wanted(void) {
         return true;
 bool cg_is_legacy_wanted(void) {
         return true;

-        /* The meaning of the kernel option is reversed wrt. to the return value
-         * of this function, hence the negation. */
-        return (wanted = r > 0 ? !b : false);
+}
+bool cg_is_hybrid_wanted(void) {
+        return false;

 }
 #endif // 0
 
 }
 #endif // 0