Obtain a list of subsystems from /proc/cgroups, and ignore hierarchies
that are not bound to any of them (especially the 'systemd' hierarchy:
http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups ).
Signed-off-by: David Ward <david.w...@ll.mit.edu>
---
src/lxc/cgroup.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index 06aa1a0..8ccbc50 100644
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -53,6 +53,39 @@ enum {
CGROUP_CLONE_CHILDREN,
};
+/* Check if a mount is a cgroup hierarchy for any subsystem.
+ * Return the first subsystem found (or NULL if none).
+ */
+static char *mount_has_subsystem(const struct mntent *mntent)
+{
+ FILE *f;
+ char *c, *ret;
+ char line[MAXPATHLEN];
+
+ /* read the list of subsystems from the kernel */
+ f = fopen("/proc/cgroups", "r");
+ if (!f)
+ return 0;
+
+ /* skip the first line, which contains column headings */
+ if (!fgets(line, MAXPATHLEN, f))
+ return 0;
+
+ while (fgets(line, MAXPATHLEN, f)) {
+ c = strchr(line, '\t');
+ if (!c)
+ continue;
+ *c = '\0';
+
+ ret = hasmntopt(mntent, line);
+ if (ret)
+ break;
+ }
+
+ fclose(f);
+ return ret;
+}
+
/*
* get_init_cgroup: get the cgroup init is in.
* dsg: preallocated buffer to put the output in
@@ -124,8 +157,15 @@ static int get_cgroup_mount(const char *subsystem, char
*mnt)
while ((mntent = getmntent(file))) {
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
- if (subsystem && !hasmntopt(mntent, subsystem))
- continue;
+
+ if (subsystem) {
+ if (!hasmntopt(mntent, subsystem))
+ continue;
+ }
+ else {
+ if (!mount_has_subsystem(mntent))
+ continue;
+ }
ret = snprintf(mnt, MAXPATHLEN, "%s%s/lxc", mntent->mnt_dir,
get_init_cgroup(subsystem, NULL, initcgroup));
@@ -252,6 +292,8 @@ int lxc_cgroup_attach(const char *name, pid_t pid)
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
+ if (!mount_has_subsystem(mntent))
+ continue;
INFO("[%d] found cgroup mounted at '%s',opts='%s'",
++found, mntent->mnt_dir, mntent->mnt_opts);
@@ -405,6 +447,8 @@ int lxc_cgroup_create(const char *name, pid_t pid)
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
+ if (!mount_has_subsystem(mntent))
+ continue;
INFO("[%d] found cgroup mounted at '%s',opts='%s'",
++found, mntent->mnt_dir, mntent->mnt_opts);
@@ -502,6 +546,8 @@ int lxc_cgroup_destroy(const char *name)
while ((mntent = getmntent(file))) {
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
+ if (!mount_has_subsystem(mntent))
+ continue;
err = lxc_one_cgroup_destroy(mntent, name);
if (err)
--
1.7.1
------------------------------------------------------------------------------
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