systemd/0002-units-enable-waiting-for-unit-termination-in-certain.patch

From d7f920bfcb0296fed214d4d3a21d64de09a68521 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 1 Sep 2015 17:25:59 +0200
Subject: [PATCH 2/2] units: enable waiting for unit termination in certain
 cases

The legacy cgroup hierarchy does not support reliable empty
notifications in containers and if there are left-over subgroups in a
cgroup. This makes it hard to correctly wait for them running empty, and
thus we previously disabled this logic entirely.

With this change we explicitly check for the container case, and whether
the unit is a "delegation" unit (i.e. one where programs may create
their own subgroups). If we are neither in a container, nor operating on
a delegation unit cgroup empty notifications become reliable and thus we
start waiting for the empty notifications again.

This doesn't really fix the general problem around cgroup notifications
but reduces the effect around it.

(This also reorders #include lines by their focus, as suggsted in
CODING_STYLE. We have to add "virt.h", so let's do that at the right
place.)

Also see #317.

(cherry picked from commit e9db43d5910717a1084924c512bf85e2b8265375)
---
 src/core/cgroup.c | 12 ++++++++++++
 src/core/cgroup.h |  2 ++
 src/core/unit.c   | 40 +++++++++++++++++++++++-----------------
 3 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 6474e08..65af351 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -1127,6 +1127,18 @@ int unit_reset_cpu_usage(Unit *u) {
         return 0;
 }
 
+bool unit_cgroup_delegate(Unit *u) {
+        CGroupContext *c;
+
+        assert(u);
+
+        c = unit_get_cgroup_context(u);
+        if (!c)
+                return false;
+
+        return c->delegate;
+}
+
 static const char* const cgroup_device_policy_table[_CGROUP_DEVICE_POLICY_MAX] = {
         [CGROUP_AUTO] = "auto",
         [CGROUP_CLOSED] = "closed",
diff --git a/src/core/cgroup.h b/src/core/cgroup.h
index 869ddae..7b38d21 100644
--- a/src/core/cgroup.h
+++ b/src/core/cgroup.h
@@ -130,5 +130,7 @@ int unit_get_memory_current(Unit *u, uint64_t *ret);
 int unit_get_cpu_usage(Unit *u, nsec_t *ret);
 int unit_reset_cpu_usage(Unit *u);
 
+bool unit_cgroup_delegate(Unit *u);
+
 const char* cgroup_device_policy_to_string(CGroupDevicePolicy i) _const_;
 CGroupDevicePolicy cgroup_device_policy_from_string(const char *s) _pure_;
diff --git a/src/core/unit.c b/src/core/unit.c
index dc7bc5a..275f567 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -28,26 +28,28 @@
 #include "sd-id128.h"
 #include "sd-messages.h"
 #include "set.h"
-#include "unit.h"
 #include "macro.h"
 #include "strv.h"
 #include "path-util.h"
-#include "load-fragment.h"
-#include "load-dropin.h"
 #include "log.h"
-#include "unit-name.h"
-#include "dbus-unit.h"
-#include "special.h"
 #include "cgroup-util.h"
 #include "missing.h"
 #include "mkdir.h"
 #include "fileio-label.h"
+#include "formats-util.h"
+#include "process-util.h"
+#include "virt.h"
 #include "bus-common-errors.h"
+#include "bus-util.h"
+#include "dropin.h"
+#include "unit-name.h"
+#include "special.h"
+#include "unit.h"
+#include "load-fragment.h"
+#include "load-dropin.h"
 #include "dbus.h"
+#include "dbus-unit.h"
 #include "execute.h"
-#include "dropin.h"
-#include "formats-util.h"
-#include "process-util.h"
 
 const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX] = {
         [UNIT_SERVICE] = &service_vtable,
@@ -3535,14 +3537,18 @@ int unit_kill_context(
                 } else if (r > 0) {
 
                         /* FIXME: For now, we will not wait for the
-                         * cgroup members to die, simply because
-                         * cgroup notification is unreliable. It
-                         * doesn't work at all in containers, and
-                         * outside of containers it can be confused
-                         * easily by leaving directories in the
-                         * cgroup. */
-
-                        /* wait_for_exit = true; */
+                         * cgroup members to die if we are running in
+                         * a container or if this is a delegation
+                         * unit, simply because cgroup notification is
+                         * unreliable in these cases. It doesn't work
+                         * at all in containers, and outside of
+                         * containers it can be confused easily by
+                         * left-over directories in the cgroup --
+                         * which however should not exist in
+                         * non-delegated units. */
+
+                        if  (detect_container(NULL) == 0 && !unit_cgroup_delegate(u))
+                                wait_for_exit = true;
 
                         if (c->send_sighup && k != KILL_KILL) {
                                 set_free(pid_set);
-- 
2.6.0