[lxc-devel] [PATCH] Ignore trailing /init.scope in init cgroups

[Serge Hallyn]

The lxc monitor does not store the container's cgroups, rather it
recalculates them whenever needed.

Systemd moves itself into a /init.scope cgroup for the systemd
controller.

It might be worth changing that (by storing all cgroup info in the
lxc_handler), but for now go the hacky route and chop off any
trailing /init.scope.

I definately thinkg we want to switch to storing as that will be
more bullet-proof, but for now we need a quick backportable fix
for systemd 226 guests.

Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
---
 src/lxc/cgfs.c      |  1 +
 src/lxc/cgmanager.c |  1 +
 src/lxc/cgroup.c    | 14 ++++++++++++++
 src/lxc/cgroup.h    |  2 ++
 4 files changed, 18 insertions(+)

diff --git a/src/lxc/cgfs.c b/src/lxc/cgfs.c
index df2e6b2..d65f2d7 100644
--- a/src/lxc/cgfs.c
+++ b/src/lxc/cgfs.c
@@ -1220,6 +1220,7 @@ static char *lxc_cgroup_get_hierarchy_path_data(const char *subsystem, struct cg
 	info = find_info_for_subsystem(info, subsystem);
 	if (!info)
 		return NULL;
+	prune_init_scope(info->cgroup_path);
 	return info->cgroup_path;
 }
 
diff --git a/src/lxc/cgmanager.c b/src/lxc/cgmanager.c
index a677c22..f868903 100644
--- a/src/lxc/cgmanager.c
+++ b/src/lxc/cgmanager.c
@@ -776,6 +776,7 @@ static char *try_get_abs_cgroup(const char *name, const char *lxcpath,
 			nerr = nih_error_get();
 			nih_free(nerr);
 		}
+		prune_init_scope(cgroup);
 		return cgroup;
 	}
 
diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index 2362ad8..b1c764f 100644
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -194,3 +194,17 @@ cgroup_driver_t cgroup_driver(void)
 {
 	return ops->driver;
 }
+
+#define INIT_SCOPE "/init.scope"
+void prune_init_scope(char *cg)
+{
+	char *point = cg + strlen(cg) - strlen(INIT_SCOPE);
+	if (point < cg)
+		return;
+	if (strcmp(point, INIT_SCOPE) == 0) {
+		if (point == cg)
+			*(point+1) = '\0';
+		else
+			*point = '\0';
+	}
+}
diff --git a/src/lxc/cgroup.h b/src/lxc/cgroup.h
index 6706939..7704c04 100644
--- a/src/lxc/cgroup.h
+++ b/src/lxc/cgroup.h
@@ -80,4 +80,6 @@ extern bool cgroup_unfreeze(struct lxc_handler *handler);
 extern void cgroup_disconnect(void);
 extern cgroup_driver_t cgroup_driver(void);
 
+extern void prune_init_scope(char *cg);
+
 #endif
-- 
2.5.0