core: Don't GC unit if it is in cgroup_empty_queue

The gc_unit_queue is dispatched before the cgroup_empty_queue.  Because
of this, when we enter in on_cgroup_empty_event, the unit in
cgroup_empty_queue may already have been freed and we don't clean up the
corresponding cgroup. With this change, we prevent the unit from being
garbage collected if it is in the cgroup_empty_queue.

diff --git a/src/core/unit.c b/src/core/unit.c
index 90f87a95f5e7d8b7443fcecd6eb2b99d94de1431..84e9185e82f76370130edd0ef505c34f2b88c7d0 100644 (file)
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -441,6 +441,9 @@ bool unit_may_gc(Unit *u) {
         if (u->perpetual)
                 return false;
 
+        if (u->in_cgroup_empty_queue)
+                return false;
+
         if (sd_bus_track_count(u->bus_track) > 0)
                 return false;
 

diff --git a/test/units/testsuite-19.cleanup-slice.sh b/test/units/testsuite-19.cleanup-slice.sh
new file mode 100755 (executable)
index 0000000..5d63160
--- /dev/null
+++ b/test/units/testsuite-19.cleanup-slice.sh
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+set -eux
+set -o pipefail
+
+# shellcheck source=test/units/util.sh
+. "$(dirname "$0")"/util.sh
+
+export SYSTEMD_LOG_LEVEL=debug
+
+# Create service with KillMode=none inside a slice
+cat <<EOF >/run/systemd/system/test19cleanup.service
+[Unit]
+Description=Test 19 cleanup Service
+[Service]
+Slice=test19cleanup.slice
+Type=exec
+ExecStart=sleep infinity
+KillMode=none
+EOF
+cat <<EOF >/run/systemd/system/test19cleanup.slice
+[Unit]
+Description=Test 19 cleanup Slice
+EOF
+
+# Start service
+systemctl start test19cleanup.service
+assert_rc 0 systemd-cgls /test19cleanup.slice
+
+pid=$(systemctl show --property MainPID --value test19cleanup)
+ps "$pid"
+
+# Stop slice
+# The sleep process will not be killed because of KillMode=none
+# Since there is still a process running under it, the /test19cleanup.slice cgroup won't be removed
+systemctl stop test19cleanup.slice
+
+ps "$pid"
+
+# Kill sleep process manually
+kill -s TERM "$pid"
+while kill -0 "$pid" 2>/dev/null; do sleep 0.1; done
+
+timeout 30 bash -c 'while systemd-cgls /test19cleanup.slice/test19cleanup.service >& /dev/null; do sleep .5; done'
+assert_rc 1 systemd-cgls /test19cleanup.slice/test19cleanup.service
+
+# Check that empty cgroup /test19cleanup.slice has been removed
+timeout 30 bash -c 'while systemd-cgls /test19cleanup.slice >& /dev/null; do sleep .5; done'
+assert_rc 1 systemd-cgls /test19cleanup.slice