From d35551d8c6a9c46442500992abfb67774f9fa8d8 Mon Sep 17 00:00:00 2001
From: Jonas Witschel <diabonas@archlinux.org>
Date: Wed, 10 Nov 2021 22:46:35 +0100
Subject: [PATCH] scope: count successful cgroup additions when delegating via
 D-Bus

Since commit 8d3e4ac7cd37200d1431411a4b98925a24b7d9b3 ("scope: refuse
activation of scopes if no PIDs to add are left") all "systemd-run --scope
--user" calls fail because cgroup attachments delegated to the system instance
are not counted towards successful additions. Fix this by incrementing the
return value in case unit_attach_pid_to_cgroup_via_bus() succeeds, similar to
what happens when cg_attach() succeeds directly.

Note that this can *not* distinguish the case when
unit_attach_pid_to_cgroup_via_bus() has been run successfully, but all
processes to attach are gone in the meantime, unlike the checks that commit
8d3e4ac7cd37200d1431411a4b98925a24b7d9b3 adds for the system instance. This is
because even though unit_attach_pid_to_cgroup_via_bus() leads to an internal
unit_attach_pids_to_cgroup() call, the return value over D-Bus does not include
the number of successfully attached processes and is always NULL on success.

Fixes: #21297
---
 src/core/cgroup.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index abc30e3990c4..c942db8d05eb 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2283,8 +2283,11 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
                                 z = unit_attach_pid_to_cgroup_via_bus(u, pid, suffix_path);
                                 if (z < 0)
                                         log_unit_info_errno(u, z, "Couldn't move process "PID_FMT" to requested cgroup '%s' (directly or via the system bus): %m", pid, empty_to_root(p));
-                                else
+                                else {
+                                        if (ret >= 0)
+                                                ret++; /* Count successful additions */
                                         continue; /* When the bus thing worked via the bus we are fully done for this PID. */
+                                }
                         }
 
                         if (ret >= 0)