core: ignore errors from cg_create_and_attach() in test mode (#8401)

Reproducer:

$ meson build && cd build
$ ninja
$ sudo useradd test
$ sudo su test
$ ./systemd --system --test
...
Failed to create /user.slice/user-1000.slice/session-6.scope/init.scope control group: Permission denied
Failed to allocate manager object: Permission denied

Above error message is caused by the fact that user test didn't have its
own session and we tried to set up init.scope already running as user
test in the directory owned by different user.

Let's try to setup cgroup hierarchy, but if that fails return error only
when not running in the test mode.

Fixes #8072

(cherry picked from commit aa77e234fce7413b7dd64f99ea51450f2e2e9dbd)

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index dd173e2a310ed1d7abb484aeb8587b253a074cb7..313801544010a9f9e64ed55fad37237896a417b5 100644 (file)
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2285,6 +2285,11 @@ int manager_setup_cgroup(Manager *m) {
         /* 5. Make sure we are in the special "init.scope" unit in the root slice. */
         scope_path = strjoina(m->cgroup_root, "/" SPECIAL_INIT_SCOPE);
         r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, scope_path, 0);
+        if (r >= 0) {
+                /* Also, move all other userspace processes remaining in the root cgroup into that scope. */
+                r = cg_migrate(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_root, SYSTEMD_CGROUP_CONTROLLER, scope_path, 0);
+                if (r < 0)
+                        log_warning_errno(r, "Couldn't move remaining userspace processes, ignoring: %m");
 #else
         /* Note:
                 * This method is in core, and normally called by systemd
@@ -2303,22 +2308,18 @@ int manager_setup_cgroup(Manager *m) {
                 scope_path = strjoina(m->cgroup_root, "/elogind");
         r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, scope_path, 0);
 #endif // 0
-        if (r < 0)
-                return log_error_errno(r, "Failed to create %s control group: %m", scope_path);
         log_debug_elogind("Created control group \"%s\"", scope_path);
 
 #if 0 /// elogind is not a "sub-controller" like systemd, so migration is not needed.
-        /* Also, move all other userspace processes remaining in the root cgroup into that scope. */
-        r = cg_migrate(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_root, SYSTEMD_CGROUP_CONTROLLER, scope_path, 0);
-        if (r < 0)
-                log_warning_errno(r, "Couldn't move remaining userspace processes, ignoring: %m");
 #endif // 0
+                /* 6. And pin it, so that it cannot be unmounted */
+                safe_close(m->pin_cgroupfs_fd);
+                m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK);
+                if (m->pin_cgroupfs_fd < 0)
+                        return log_error_errno(errno, "Failed to open pin file: %m");
 
-        /* 6. And pin it, so that it cannot be unmounted */
-        safe_close(m->pin_cgroupfs_fd);
-        m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK);
-        if (m->pin_cgroupfs_fd < 0)
-                return log_error_errno(errno, "Failed to open pin file: %m");
+        } else if (r < 0 && !m->test_run_flags)
+                return log_error_errno(r, "Failed to create %s control group: %m", scope_path);
 
         /* 7. Always enable hierarchical support if it exists... */
         if (!all_unified && m->test_run_flags == 0)