cgroup: if we do a cgroup operation then do something on all supported controllers

Previously we did operations like attach, trim or migrate only on the
controllers that were enabled for a specific unit. With this changes we
will now do them for all supproted controllers, and fall back to all
possible prefix paths if the specified paths do not exist.

This fixes issues if a controller is being disabled for a unit where it
was previously enabled, and makes sure that all processes stay as "far
down" the tree as groups exist.

9 files changed, 118 insertions, 70 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index e66b8f4851..8bf4d896de 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -397,13 +397,13 @@ static int unit_create_cgroups(Unit *u, CGroupControllerMask mask) {
         }
 
         /* First, create our own group */
-        r = cg_create_with_mask(mask, path);
+        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 && !streq(path, u->cgroup_path)) {
-                r = cg_migrate_with_mask(mask, u->cgroup_path, path);
+        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 %s: %s", path, strerror(-r));
         }
@@ -537,7 +537,7 @@ void unit_destroy_cgroup(Unit *u) {
         if (!u->cgroup_path)
                 return;
 
-        r = cg_trim_with_mask(u->cgroup_mask, u->cgroup_path, !unit_has_name(u, SPECIAL_ROOT_SLICE));
+        r = cg_trim_everywhere(u->manager->cgroup_supported, u->cgroup_path, !unit_has_name(u, SPECIAL_ROOT_SLICE));
         if (r < 0)
                 log_debug("Failed to destroy cgroup %s: %s", u->cgroup_path, strerror(-r));
 
diff --git a/src/core/execute.c b/src/core/execute.c
index f840642d14..0bfa41836a 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -1017,7 +1017,7 @@ int exec_spawn(ExecCommand *command,
                bool apply_chroot,
                bool apply_tty_stdin,
                bool confirm_spawn,
-               CGroupControllerMask cgroup_mask,
+               CGroupControllerMask cgroup_supported,
                const char *cgroup_path,
                const char *unit_id,
                int idle_pipe[4],
@@ -1198,7 +1198,7 @@ int exec_spawn(ExecCommand *command,
                 }
 
                 if (cgroup_path) {
-                        err = cg_attach_with_mask(cgroup_mask, cgroup_path, 0);
+                        err = cg_attach_everywhere(cgroup_supported, cgroup_path, 0);
                         if (err < 0) {
                                 r = EXIT_CGROUP;
                                 goto fail_child;
diff --git a/src/core/mount.c b/src/core/mount.c
index 5c18d4e463..78c5c1e6d6 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -888,7 +888,7 @@ static int mount_spawn(Mount *m, ExecCommand *c, pid_t *_pid) {
                        true,
                        true,
                        UNIT(m)->manager->confirm_spawn,
-                       UNIT(m)->cgroup_mask,
+                       UNIT(m)->manager->cgroup_supported,
                        UNIT(m)->cgroup_path,
                        UNIT(m)->id,
                        NULL,
diff --git a/src/core/scope.c b/src/core/scope.c
index b94f3ff7ba..50e5dbacb4 100644
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -257,7 +257,7 @@ static int scope_start(Unit *u) {
                 return r;
         }
 
-        r = cg_attach_many_with_mask(u->cgroup_mask, u->cgroup_path, s->pids);
+        r = cg_attach_many_everywhere(u->manager->cgroup_supported, u->cgroup_path, s->pids);
         if (r < 0)
                 return r;
 
diff --git a/src/core/service.c b/src/core/service.c
index cc61b546fc..24b7bef287 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -1820,7 +1820,7 @@ static int service_spawn(
                        apply_chroot,
                        apply_tty_stdin,
                        UNIT(s)->manager->confirm_spawn,
-                       UNIT(s)->cgroup_mask,
+                       UNIT(s)->manager->cgroup_supported,
                        path,
                        UNIT(s)->id,
                        s->type == SERVICE_IDLE ? UNIT(s)->manager->idle_pipe : NULL,
diff --git a/src/core/socket.c b/src/core/socket.c
index 46a73e0108..190b36c3ca 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -1239,7 +1239,7 @@ static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
                        true,
                        true,
                        UNIT(s)->manager->confirm_spawn,
-                       UNIT(s)->cgroup_mask,
+                       UNIT(s)->manager->cgroup_supported,
                        UNIT(s)->cgroup_path,
                        UNIT(s)->id,
                        NULL,
diff --git a/src/core/swap.c b/src/core/swap.c
index 82bfad187e..dc6731ab30 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -625,7 +625,7 @@ static int swap_spawn(Swap *s, ExecCommand *c, pid_t *_pid) {
                        true,
                        true,
                        UNIT(s)->manager->confirm_spawn,
-                       UNIT(s)->cgroup_mask,
+                       UNIT(s)->manager->cgroup_supported,
                        UNIT(s)->cgroup_path,
                        UNIT(s)->id,
                        NULL,
diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
index 0bffebdac8..2e630d4708 100644
--- a/src/shared/cgroup-util.c
+++ b/src/shared/cgroup-util.c
@@ -435,6 +435,46 @@ int cg_migrate_recursive(
         return ret;
 }
 
+int cg_migrate_recursive_fallback(
+                const char *cfrom,
+                const char *pfrom,
+                const char *cto,
+                const char *pto,
+                bool ignore_self,
+                bool rem) {
+
+        int r;
+
+        assert(cfrom);
+        assert(pfrom);
+        assert(cto);
+        assert(pto);
+
+        r = cg_migrate_recursive(cfrom, pfrom, cto, pto, ignore_self, rem);
+        if (r < 0) {
+                char prefix[strlen(pto) + 1];
+
+                /* This didn't work? Then let's try all prefixes of the destination */
+
+                strcpy(prefix, pto);
+                for (;;) {
+                        char *slash;
+
+                        slash = strrchr(prefix, '/');
+                        if (!slash)
+                                break;
+
+                        *slash = 0;
+
+                        r = cg_migrate_recursive(cfrom, pfrom, cto, prefix, ignore_self, rem);
+                        if (r >= 0)
+                                break;
+                }
+        }
+
+        return r;
+}
+
 static const char *normalize_controller(const char *controller) {
 
         assert(controller);
@@ -607,6 +647,39 @@ int cg_attach(const char *controller, const char *path, pid_t pid) {
         return write_string_file(fs, c);
 }
 
+int cg_attach_fallback(const char *controller, const char *path, pid_t pid) {
+        int r;
+
+        assert(controller);
+        assert(path);
+        assert(pid >= 0);
+
+        r = cg_attach(controller, path, pid);
+        if (r < 0) {
+                char prefix[strlen(path) + 1];
+
+                /* This didn't work? Then let's try all prefixes of
+                 * the destination */
+
+                strcpy(prefix, path);
+                for (;;) {
+                        char *slash;
+
+                        slash = strrchr(prefix, '/');
+                        if (!slash)
+                                break;
+
+                        *slash = 0;
+
+                        r = cg_attach(controller, prefix, pid);
+                        if (r >= 0)
+                                break;
+                }
+        }
+
+        return r;
+}
+
 int cg_set_group_access(
                 const char *controller,
                 const char *path,
@@ -1607,7 +1680,7 @@ static const char mask_names[] =
         "memory\0"
         "devices\0";
 
-int cg_create_with_mask(CGroupControllerMask mask, const char *path) {
+int cg_create_everywhere(CGroupControllerMask supported, CGroupControllerMask mask, const char *path) {
         CGroupControllerMask bit = 1;
         const char *n;
         int r;
@@ -1623,102 +1696,75 @@ int cg_create_with_mask(CGroupControllerMask mask, const char *path) {
 
         /* Then, do the same in the other hierarchies */
         NULSTR_FOREACH(n, mask_names) {
-                if (bit & mask)
+                if (mask & bit)
                         cg_create(n, path);
-                else
+                else if (supported & bit)
                         cg_trim(n, path, true);
 
                 bit <<= 1;
         }
 
-        return r;
+        return 0;
 }
 
-int cg_attach_with_mask(CGroupControllerMask mask, const char *path, pid_t pid) {
+int cg_attach_everywhere(CGroupControllerMask supported, const char *path, pid_t pid) {
         CGroupControllerMask bit = 1;
         const char *n;
         int r;
 
         r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, path, pid);
+        if (r < 0)
+                return r;
 
         NULSTR_FOREACH(n, mask_names) {
-                if (bit & mask)
-                        cg_attach(n, path, pid);
-                else {
-                        char prefix[strlen(path) + 1], *slash;
-
-                        /* OK, this one is a bit harder... Now we need
-                         * to add to the closest parent cgroup we
-                         * can find */
-                        strcpy(prefix, path);
-                        while ((slash = strrchr(prefix, '/'))) {
-                                int q;
-                                *slash = 0;
-
-                                q = cg_attach(n, prefix, pid);
-                                if (q >= 0)
-                                        break;
-                        }
-                }
+                if (supported & bit)
+                        cg_attach_fallback(n, path, pid);
 
                 bit <<= 1;
         }
 
-        return r;
+        return 0;
 }
 
-int cg_attach_many_with_mask(CGroupControllerMask mask, const char *path, Set* pids) {
+int cg_attach_many_everywhere(CGroupControllerMask supported, const char *path, Set* pids) {
         Iterator i;
         void *pidp;
         int r = 0;
 
         SET_FOREACH(pidp, pids, i) {
                 pid_t pid = PTR_TO_LONG(pidp);
-                int k;
+                int q;
 
-                k = cg_attach_with_mask(mask, path, pid);
-                if (k < 0)
-                        r = k;
+                q = cg_attach_everywhere(supported, path, pid);
+                if (q < 0)
+                        r = q;
         }
 
         return r;
 }
 
-int cg_migrate_with_mask(CGroupControllerMask mask, const char *from, const char *to) {
+int cg_migrate_everywhere(CGroupControllerMask supported, const char *from, const char *to) {
         CGroupControllerMask bit = 1;
         const char *n;
         int r;
 
-        if (path_equal(from, to))
-                return 0;
-
-        r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, from, SYSTEMD_CGROUP_CONTROLLER, to, false, true);
+        if (!path_equal(from, to))  {
+                r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, from, SYSTEMD_CGROUP_CONTROLLER, to, false, true);
+                if (r < 0)
+                        return r;
+        }
 
         NULSTR_FOREACH(n, mask_names) {
-                if (bit & mask)
-                        cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, to, n, to, false, false);
-                else {
-                        char prefix[strlen(to) + 1], *slash;
-
-                        strcpy(prefix, to);
-                        while ((slash = strrchr(prefix, '/'))) {
-                                int q;
-
-                                *slash = 0;
-
-                                q = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, to, n, prefix, false, false);
-                                if (q >= 0)
-                                        break;
-                        }
-                }
+                if (supported & bit)
+                        cg_migrate_recursive_fallback(SYSTEMD_CGROUP_CONTROLLER, to, n, to, false, false);
 
                 bit <<= 1;
         }
 
-        return r;
+        return 0;
 }
 
-int cg_trim_with_mask(CGroupControllerMask mask, const char *path, bool delete_root) {
+int cg_trim_everywhere(CGroupControllerMask supported, const char *path, bool delete_root) {
         CGroupControllerMask bit = 1;
         const char *n;
         int r;
@@ -1728,13 +1774,13 @@ int cg_trim_with_mask(CGroupControllerMask mask, const char *path, bool delete_r
                 return r;
 
         NULSTR_FOREACH(n, mask_names) {
-                if (bit & mask)
+                if (supported & bit)
                         cg_trim(n, path, delete_root);
 
                 bit <<= 1;
         }
 
-        return r;
+        return 0;
 }
 
 CGroupControllerMask cg_mask_supported(void) {
diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h
index 0fc93c12c8..0963450b08 100644
--- a/src/shared/cgroup-util.h
+++ b/src/shared/cgroup-util.h
@@ -64,6 +64,7 @@ int cg_kill_recursive_and_wait(const char *controller, const char *path, bool re
 
 int cg_migrate(const char *cfrom, const char *pfrom, const char *cto, const char *pto, bool ignore_self);
 int cg_migrate_recursive(const char *cfrom, const char *pfrom, const char *cto, const char *pto, bool ignore_self, bool remove);
+int cg_migrate_recursive_fallback(const char *cfrom, const char *pfrom, const char *cto, const char *pto, bool ignore_self, bool rem);
 
 int cg_split_spec(const char *spec, char **controller, char **path);
 int cg_join_spec(const char *controller, const char *path, char **spec);
@@ -81,6 +82,7 @@ int cg_delete(const char *controller, const char *path);
 
 int cg_create(const char *controller, const char *path);
 int cg_attach(const char *controller, const char *path, pid_t pid);
+int cg_attach_fallback(const char *controller, const char *path, pid_t pid);
 int cg_create_and_attach(const char *controller, const char *path, pid_t pid);
 
 int cg_set_attribute(const char *controller, const char *path, const char *attribute, const char *value);
@@ -126,10 +128,10 @@ bool cg_controller_is_valid(const char *p, bool allow_named);
 
 int cg_slice_to_path(const char *unit, char **ret);
 
-int cg_create_with_mask(CGroupControllerMask mask, const char *path);
-int cg_attach_with_mask(CGroupControllerMask mask, const char *path, pid_t pid);
-int cg_attach_many_with_mask(CGroupControllerMask mask, const char *path, Set* pids);
-int cg_migrate_with_mask(CGroupControllerMask mask, const char *from, const char *to);
-int cg_trim_with_mask(CGroupControllerMask mask, const char *path, bool delete_root);
+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_trim_everywhere(CGroupControllerMask supported, const char *path, bool delete_root);
 
 CGroupControllerMask cg_mask_supported(void);