cgroup: optionally mount a specific cgroup controllers together, and add cpu+cpuacct to the default

src/automount.c

@@ -611,7 +611,7 @@ static int automount_start(Unit *u) {
 
         assert(a->state == AUTOMOUNT_DEAD || a->state == AUTOMOUNT_FAILED);
 
-        if (path_is_mount_point(a->where)) {
+        if (path_is_mount_point(a->where, false)) {
                 log_error("Path %s is already a mount point, refusing start for %s", a->where, u->meta.id);
                 return -EEXIST;
         }

src/cgroup-util.c

@@ -513,7 +513,7 @@ int cg_get_path(const char *controller, const char *path, const char *suffix, ch
         if (_unlikely_(!good)) {
                 int r;
 
-                r = path_is_mount_point("/sys/fs/cgroup");
+                r = path_is_mount_point("/sys/fs/cgroup", false);
                 if (r <= 0)
                         return r < 0 ? r : -ENOENT;
 

src/cgroup.c

@@ -270,7 +270,7 @@ int manager_setup_cgroup(Manager *m) {
         assert(m);
 
         /* 0. Be nice to Ingo Molnar #628004 */
-        if (path_is_mount_point("/sys/fs/cgroup/systemd") <= 0) {
+        if (path_is_mount_point("/sys/fs/cgroup/systemd", false) <= 0) {
                 log_warning("No control group support available, not creating root group.");
                 return 0;
         }

src/main.c

@@ -75,6 +75,7 @@ static bool arg_sysv_console = true;
 static bool arg_mount_auto = true;
 static bool arg_swap_auto = true;
 static char **arg_default_controllers = NULL;
+static char ***arg_join_controllers = NULL;
 static ExecOutput arg_default_std_output = EXEC_OUTPUT_INHERIT;
 static ExecOutput arg_default_std_error = EXEC_OUTPUT_INHERIT;
 
@@ -494,6 +495,124 @@ static int config_parse_cpu_affinity2(
         return 0;
 }
 
+static void strv_free_free(char ***l) {
+        char ***i;
+
+        if (!l)
+                return;
+
+        for (i = l; *i; i++)
+                strv_free(*i);
+
+        free(l);
+}
+
+static void free_join_controllers(void) {
+        if (!arg_join_controllers)
+                return;
+
+        strv_free_free(arg_join_controllers);
+        arg_join_controllers = NULL;
+}
+
+static int config_parse_join_controllers(
+                const char *filename,
+                unsigned line,
+                const char *section,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        unsigned n = 0;
+        char *state, *w;
+        size_t length;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        free_join_controllers();
+
+        FOREACH_WORD_QUOTED(w, length, rvalue, state) {
+                char *s, **l;
+
+                s = strndup(w, length);
+                if (!s)
+                        return -ENOMEM;
+
+                l = strv_split(s, ",");
+                free(s);
+
+                strv_uniq(l);
+
+                if (strv_length(l) <= 1) {
+                        strv_free(l);
+                        continue;
+                }
+
+                if (!arg_join_controllers) {
+                        arg_join_controllers = new(char**, 2);
+                        if (!arg_join_controllers) {
+                                strv_free(l);
+                                return -ENOMEM;
+                        }
+
+                        arg_join_controllers[0] = l;
+                        arg_join_controllers[1] = NULL;
+
+                        n = 1;
+                } else {
+                        char ***a;
+                        char ***t;
+
+                        t = new0(char**, n+2);
+                        if (!t) {
+                                strv_free(l);
+                                return -ENOMEM;
+                        }
+
+                        n = 0;
+
+                        for (a = arg_join_controllers; *a; a++) {
+
+                                if (strv_overlap(*a, l)) {
+                                        char **c;
+
+                                        c = strv_merge(*a, l);
+                                        if (!c) {
+                                                strv_free(l);
+                                                strv_free_free(t);
+                                                return -ENOMEM;
+                                        }
+
+                                        strv_free(l);
+                                        l = c;
+                                } else {
+                                        char **c;
+
+                                        c = strv_copy(*a);
+                                        if (!c) {
+                                                strv_free(l);
+                                                strv_free_free(t);
+                                                return -ENOMEM;
+                                        }
+
+                                        t[n++] = c;
+                                }
+                        }
+
+                        t[n++] = strv_uniq(l);
+
+                        strv_free_free(arg_join_controllers);
+                        arg_join_controllers = t;
+                }
+        }
+
+        return 0;
+}
+
 static int parse_config_file(void) {
 
         const ConfigTableItem items[] = {
@@ -514,6 +633,7 @@ static int parse_config_file(void) {
                 { "Manager", "DefaultControllers",    config_parse_strv,         0, &arg_default_controllers },
                 { "Manager", "DefaultStandardOutput", config_parse_output,       0, &arg_default_std_output  },
                 { "Manager", "DefaultStandardError",  config_parse_output,       0, &arg_default_std_error   },
+                { "Manager", "JoinControllers",       config_parse_join_controllers, 0, &arg_join_controllers },
                 { NULL, NULL, NULL, 0, NULL }
         };
 
@@ -1084,14 +1204,28 @@ int main(int argc, char *argv[]) {
                 log_open();
         }
 
+        /* Initialize default unit */
         if (set_default_unit(SPECIAL_DEFAULT_TARGET) < 0)
                 goto finish;
 
+        /* By default, mount "cpu" and "cpuacct" together */
+        arg_join_controllers = new(char**, 2);
+        if (!arg_join_controllers)
+                goto finish;
+
+        arg_join_controllers[0] = strv_new("cpu", "cpuacct", NULL);
+        arg_join_controllers[1] = NULL;
+
+        if (!arg_join_controllers[0])
+                goto finish;
+
         /* Mount /proc, /sys and friends, so that /proc/cmdline and
          * /proc/$PID/fd is available. */
-        if (geteuid() == 0 && !getenv("SYSTEMD_SKIP_API_MOUNTS"))
-                if (mount_setup(loaded_policy) < 0)
+        if (geteuid() == 0 && !getenv("SYSTEMD_SKIP_API_MOUNTS")) {
+                r = mount_setup(loaded_policy);
+                if (r < 0)
                         goto finish;
+        }
 
         /* Reset all signal handlers. */
         assert_se(reset_all_signal_handlers() == 0);
@@ -1199,6 +1333,12 @@ int main(int argc, char *argv[]) {
         if (getpid() == 1)
                 install_crash_handler();
 
+        if (geteuid() == 0 && !getenv("SYSTEMD_SKIP_API_MOUNTS")) {
+                r = mount_cgroup_controllers(arg_join_controllers);
+                if (r < 0)
+                        goto finish;
+        }
+
         log_full(arg_running_as == MANAGER_SYSTEM ? LOG_INFO : LOG_DEBUG,
                  PACKAGE_STRING " running in %s mode. (" SYSTEMD_FEATURES "; " DISTRIBUTION ")", manager_running_as_to_string(arg_running_as));
 
@@ -1368,6 +1508,7 @@ finish:
 
         free(arg_default_unit);
         strv_free(arg_default_controllers);
+        free_join_controllers();
 
         dbus_shutdown();
 

src/mount-setup.c

@@ -34,6 +34,8 @@
 #include "macro.h"
 #include "util.h"
 #include "label.h"
+#include "set.h"
+#include "strv.h"
 
 #ifndef TTY_GID
 #define TTY_GID 5
@@ -104,7 +106,7 @@ static int mount_one(const MountPoint *p, bool relabel) {
         if (relabel)
                 label_fix(p->where, true);
 
-        if ((r = path_is_mount_point(p->where)) < 0)
+        if ((r = path_is_mount_point(p->where, true)) < 0)
                 return r;
 
         if (r > 0)
@@ -133,7 +135,7 @@ static int mount_one(const MountPoint *p, bool relabel) {
         if (relabel)
                 label_fix(p->where, false);
 
-        return 0;
+        return 1;
 }
 
 int mount_setup_early(void) {
@@ -155,25 +157,33 @@ int mount_setup_early(void) {
         return r;
 }
 
-static int mount_cgroup_controllers(void) {
+int mount_cgroup_controllers(char ***join_controllers) {
         int r;
         FILE *f;
         char buf[LINE_MAX];
+        Set *controllers;
 
         /* Mount all available cgroup controllers that are built into the kernel. */
 
-        if (!(f = fopen("/proc/cgroups", "re"))) {
+        f = fopen("/proc/cgroups", "re");
+        if (!f) {
                 log_error("Failed to enumerate cgroup controllers: %m");
                 return 0;
         }
 
+        controllers = set_new(string_hash_func, string_compare_func);
+        if (!controllers) {
+                r = -ENOMEM;
+                log_error("Failed to allocate controller set.");
+                goto finish;
+        }
+
         /* Ignore the header line */
         (void) fgets(buf, sizeof(buf), f);
 
         for (;;) {
-                MountPoint p;
-                char *controller, *where;
-                int enabled = false;
+                char *controller;
+                int enabled = 0;
 
                 if (fscanf(f, "%ms %*i %*i %i", &controller, &enabled) != 2) {
 
@@ -190,8 +200,66 @@ static int mount_cgroup_controllers(void) {
                         continue;
                 }
 
-                if (asprintf(&where, "/sys/fs/cgroup/%s", controller) < 0) {
+                r = set_put(controllers, controller);
+                if (r < 0) {
+                        log_error("Failed to add controller to set.");
                         free(controller);
+                        goto finish;
+                }
+        }
+
+        for (;;) {
+                MountPoint p;
+                char *controller, *where, *options;
+                char ***k = NULL;
+
+                controller = set_steal_first(controllers);
+                if (!controller)
+                        break;
+
+                if (join_controllers)
+                        for (k = join_controllers; *k; k++)
+                                if (strv_find(*k, controller))
+                                        break;
+
+                if (k && *k) {
+                        char **i, **j;
+
+                        for (i = *k, j = *k; *i; i++) {
+
+                                if (!streq(*i, controller)) {
+                                        char *t;
+
+                                        t = set_remove(controllers, *i);
+                                        if (!t) {
+                                                free(*i);
+                                                continue;
+                                        }
+                                        free(t);
+                                }
+
+                                *(j++) = *i;
+                        }
+
+                        *j = NULL;
+
+                        options = strv_join(*k, ",");
+                        if (!options) {
+                                log_error("Failed to join options");
+                                free(controller);
+                                r = -ENOMEM;
+                                goto finish;
+                        }
+
+                } else {
+                        options = controller;
+                        controller = NULL;
+                }
+
+                where = strappend("/sys/fs/cgroup/", options);
+                if (!where) {
+                        log_error("Failed to build path");
+                        free(options);
                         r = -ENOMEM;
                         goto finish;
                 }
@@ -200,7 +268,7 @@ static int mount_cgroup_controllers(void) {
                 p.what = "cgroup";
                 p.where = where;
                 p.type = "cgroup";
-                p.options = controller;
+                p.options = options;
                 p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
                 p.fatal = false;
 
@@ -208,13 +276,45 @@ static int mount_cgroup_controllers(void) {
                 free(controller);
                 free(where);
 
-                if (r < 0)
+                if (r < 0) {
+                        free(options);
                         goto finish;
+                }
+
+                if (r > 0 && k && *k) {
+                        char **i;
+
+                        for (i = *k; *i; i++) {
+                                char *t;
+
+                                t = strappend("/sys/fs/cgroup/", *i);
+                                if (!t) {
+                                        log_error("Failed to build path");
+                                        r = -ENOMEM;
+                                        free(options);
+                                        goto finish;
+                                }
+
+                                r = symlink(options, t);
+                                free(t);
+
+                                if (r < 0 && errno != EEXIST) {
+                                        log_error("Failed to create symlink: %m");
+                                        r = -errno;
+                                        free(options);
+                                        goto finish;
+                                }
+                        }
+                }
+
+                free(options);
         }
 
         r = 0;
 
 finish:
+        set_free_free(controllers);
+
         fclose(f);
 
         return r;
@@ -301,5 +401,5 @@ int mount_setup(bool loaded_policy) {
         mkdir("/run/systemd", 0755);
         mkdir("/run/systemd/system", 0755);
 
-        return mount_cgroup_controllers();
+        return 0;
 }

src/mount-setup.h

@@ -28,6 +28,8 @@ int mount_setup_early(void);
 
 int mount_setup(bool loaded_policy);
 
+int mount_cgroup_controllers(char ***join_controllers);
+
 bool mount_point_is_api(const char *path);
 bool mount_point_ignore(const char *path);
 

src/nspawn.c

@@ -167,7 +167,7 @@ static int mount_all(const char *dest) {
                         break;
                 }
 
-                if ((t = path_is_mount_point(where)) < 0) {
+                if ((t = path_is_mount_point(where, false)) < 0) {
                         log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));
                         free(where);
 

src/strv.c

@@ -660,3 +660,16 @@ char **strv_parse_nulstr(const char *s, size_t l) {
 
         return v;
 }
+
+bool strv_overlap(char **a, char **b) {
+        char **i, **j;
+
+        STRV_FOREACH(i, a) {
+                STRV_FOREACH(j, b) {
+                        if (streq(*i, *j))
+                                return true;
+                }
+        }
+
+        return false;
+}

src/strv.h

@@ -68,6 +68,8 @@ char **strv_env_clean(char **l);
 
 char **strv_parse_nulstr(const char *s, size_t l);
 
+bool strv_overlap(char **a, char **b);
+
 #define STRV_FOREACH(s, l)                      \
         for ((s) = (l); (s) && *(s); (s)++)
 

src/system.conf

@@ -23,3 +23,4 @@
 #DefaultControllers=cpu
 #DefaultStandardOutput=inherit
 #DefaultStandardError=inherit
+#JoinControllers=cpu,cpuacct

src/util.c

@@ -2895,19 +2895,25 @@ ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
         return n;
 }
 
-int path_is_mount_point(const char *t) {
+int path_is_mount_point(const char *t, bool allow_symlink) {
         struct stat a, b;
         char *parent;
         int r;
 
-        if (lstat(t, &a) < 0) {
+        if (allow_symlink)
+                r = stat(t, &a);
+        else
+                r = lstat(t, &a);
+
+        if (r < 0) {
                 if (errno == ENOENT)
                         return 0;
 
                 return -errno;
         }
 
-        if ((r = parent_of_path(t, &parent)) < 0)
+        r = parent_of_path(t, &parent);
+        if (r < 0)
                 return r;
 
         r = lstat(parent, &b);

src/util.h

@@ -341,7 +341,7 @@ int fopen_temporary(const char *path, FILE **_f, char **_temp_path);
 ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll);
 ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll);
 
-int path_is_mount_point(const char *path);
+int path_is_mount_point(const char *path, bool allow_symlink);
 
 bool is_device_path(const char *path);