core: find the closest parent slice that has a specfic cgroup controller enabled when enabling/disabling cgroup controllers for units

3 files changed, 50 insertions, 29 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index f0420ebc0..24d6ff648 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -448,9 +448,26 @@ void unit_update_cgroup_members_masks(Unit *u) {
         }
 }
 
+static const char *migrate_callback(CGroupControllerMask mask, void *userdata) {
+        Unit *u = userdata;
+
+        assert(mask != 0);
+        assert(u);
+
+        while (u) {
+                if (u->cgroup_path &&
+                    u->cgroup_realized &&
+                    (u->cgroup_realized_mask & mask) == mask)
+                        return u->cgroup_path;
+
+                u = UNIT_DEREF(u->slice);
+        }
+
+        return NULL;
+}
+
 static int unit_create_cgroups(Unit *u, CGroupControllerMask mask) {
-        _cleanup_free_ char *path;
-        bool was_in_hash = false;
+        _cleanup_free_ char *path = NULL;
         int r;
 
         assert(u);
@@ -460,38 +477,31 @@ static int unit_create_cgroups(Unit *u, CGroupControllerMask mask) {
                 return log_oom();
 
         r = hashmap_put(u->manager->cgroup_unit, path, u);
-        if (r == 0)
-                was_in_hash = true;
-        else if (r < 0) {
-                log_error(r == -EEXIST ?
-                          "cgroup %s exists already: %s" : "hashmap_put failed for %s: %s",
-                          path, strerror(-r));
+        if (r < 0) {
+                log_error(r == -EEXIST ? "cgroup %s exists already: %s" : "hashmap_put failed for %s: %s", path, strerror(-r));
                 return r;
         }
-
-        /* First, create our own group */
-        r = cg_create_everywhere(u->manager->cgroup_supported, mask, path);
-        if (r < 0)
-                log_error("Failed to create cgroup %s: %s", path, strerror(-r));
-
-        /* Then, possibly move things over */
-        if (u->cgroup_path) {
-                r = cg_migrate_everywhere(u->manager->cgroup_supported, u->cgroup_path, path);
-                if (r < 0)
-                        log_error("Failed to migrate cgroup from %s to %s: %s",
-                                  u->cgroup_path, path, strerror(-r));
-        }
-
-        if (!was_in_hash) {
-                /* Remember the new data */
-                free(u->cgroup_path);
+        if (r > 0) {
                 u->cgroup_path = path;
                 path = NULL;
         }
 
+        /* First, create our own group */
+        r = cg_create_everywhere(u->manager->cgroup_supported, mask, u->cgroup_path);
+        if (r < 0) {
+                log_error("Failed to create cgroup %s: %s", u->cgroup_path, strerror(-r));
+                return r;
+        }
+
+        /* Keep track that this is now realized */
         u->cgroup_realized = true;
         u->cgroup_realized_mask = mask;
 
+        /* Then, possibly move things over */
+        r = cg_migrate_everywhere(u->manager->cgroup_supported, u->cgroup_path, u->cgroup_path, migrate_callback, u);
+        if (r < 0)
+                log_warning("Failed to migrate cgroup from to %s: %s", u->cgroup_path, strerror(-r));
+
         return 0;
 }
 
diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
index 9692a07f5..1aa81c2cd 100644
--- a/src/shared/cgroup-util.c
+++ b/src/shared/cgroup-util.c
@@ -1668,7 +1668,7 @@ int cg_attach_many_everywhere(CGroupControllerMask supported, const char *path,
         return r;
 }
 
-int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, const char *to) {
+int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, const char *to, cg_migrate_callback_t to_callback, void *userdata) {
         CGroupControllerMask bit = 1;
         const char *n;
         int r;
@@ -1680,8 +1680,17 @@ int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, cons
         }
 
         NULSTR_FOREACH(n, mask_names) {
-                if (supported & bit)
-                        cg_migrate_recursive_fallback(SYSTEMD_CGROUP_CONTROLLER, to, n, to, false, false);
+                if (supported & bit) {
+                        const char *p = NULL;
+
+                        if (to_callback)
+                                p = to_callback(bit, userdata);
+
+                        if (!p)
+                                p = to;
+
+                        cg_migrate_recursive_fallback(SYSTEMD_CGROUP_CONTROLLER, to, n, p, false, false);
+                }
 
                 bit <<= 1;
         }
diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h
index 743d902e2..aca4e44c4 100644
--- a/src/shared/cgroup-util.h
+++ b/src/shared/cgroup-util.h
@@ -122,10 +122,12 @@ bool cg_controller_is_valid(const char *p, bool allow_named);
 
 int cg_slice_to_path(const char *unit, char **ret);
 
+typedef const char* (*cg_migrate_callback_t)(CGroupControllerMask mask, void *userdata);
+
 int cg_create_everywhere(CGroupControllerMask supported, CGroupControllerMask mask, const char *path);
 int cg_attach_everywhere(CGroupControllerMask supported, const char *path, pid_t pid);
 int cg_attach_many_everywhere(CGroupControllerMask supported, const char *path, Set* pids);
-int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, const char *to);
+int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, const char *to, cg_migrate_callback_t callback, void *userdata);
 int cg_trim_everywhere(CGroupControllerMask supported, const char *path, bool delete_root);
 
 CGroupControllerMask cg_mask_supported(void);