Hi,
as promised last week, here's my patch for cpuset cgroup support for
kernels without the cgroup.clone_children feature.
My initial patch used "#include <linux/version.h>" and the macros defined
there to decide if cgroup.clone_children should be used or not. After
having seen Serge Hallyn's patch which he posted to the list last Wednesday,
where he used stat() to check if the cgroup.clone_children file is there,
I rewrote my patch to do the same.
The patch is against 1.0.0.beta3, and it is tested successfully with
RHEL-6's kernel version 2.6.32-431.3.1.el6, compiled without cgmanager
(I've so far not tried to use cgmanager in RHEL-6).
In addition to fixing the cpuset cgroup setup, this patch also fixes a
wrong argument in a call to handle_cgroup_settings() in the same context.
Robert
Signed-off-by: Robert Vogelgesang <vo...@users.sourceforge.net>
diff -u lxc-lxc-1.0.0.beta3/src/lxc/cgroup.c.cpuset2632
lxc-lxc-1.0.0.beta3/src/lxc/cgroup.c
--- lxc-lxc-1.0.0.beta3/src/lxc/cgroup.c.cpuset2632 2014-01-27
14:52:20.000000000 +0100
+++ lxc-lxc-1.0.0.beta3/src/lxc/cgroup.c 2014-01-27 16:50:11.000000000
+0100
@@ -74,6 +74,7 @@
static int cgroup_recursive_task_count(const char *cgroup_path);
static int count_lines(const char *fn);
static int handle_cgroup_settings(struct cgroup_mount_point *mp, char
*cgroup_path);
+static bool init_cpuset_if_needed(struct cgroup_mount_point *mp, const char
*path);
static struct cgroup_ops cgfs_ops;
struct cgroup_ops *active_cg_ops = &cgfs_ops;
@@ -897,15 +898,23 @@
r = lxc_grow_array((void
***)&info_ptr->created_paths, &info_ptr->created_paths_capacity,
info_ptr->created_paths_count + 1, 8);
if (r < 0)
goto cleanup_from_error;
+ if
(!init_cpuset_if_needed(info_ptr->designated_mount_point, current_entire_path))
{
+ ERROR("Failed to initialize cpuset in
new '%s'.", current_entire_path);
+ goto cleanup_from_error;
+ }
info_ptr->created_paths[info_ptr->created_paths_count++] = current_entire_path;
} else {
/* if we didn't create the cgroup, then we have
to make sure that
* further cgroups will be created properly
*/
- if (handle_cgroup_settings(mp,
info_ptr->cgroup_path) < 0) {
+ if
(handle_cgroup_settings(info_ptr->designated_mount_point,
info_ptr->cgroup_path) < 0) {
ERROR("Could not set clone_children to
1 for cpuset hierarchy in pre-existing cgroup.");
goto cleanup_from_error;
}
+ if
(!init_cpuset_if_needed(info_ptr->designated_mount_point,
info_ptr->cgroup_path)) {
+ ERROR("Failed to initialize cpuset in
pre-existing '%s'.", info_ptr->cgroup_path);
+ goto cleanup_from_error;
+ }
/* already existed but path component of
pattern didn't contain '%n',
* so this is not an error; but then we don't
need current_entire_path
@@ -2039,8 +2048,19 @@
*/
if (lxc_string_in_array("cpuset", (const char
**)mp->hierarchy->subsystems)) {
char *cc_path = cgroup_to_absolute_path(mp, cgroup_path,
"/cgroup.clone_children");
+ struct stat sb;
+
if (!cc_path)
return -1;
+ /* cgroup.clone_children is not available when running under
+ * older kernel versions; in this case, we'll initialize
+ * cpuset.cpus and cpuset.mems later, after the new cgroup
+ * was created
+ */
+ if (stat(cc_path, &sb) != 0 && errno == ENOENT) {
+ free(cc_path);
+ return 0;
+ }
r = lxc_read_from_file(cc_path, buf, 1);
if (r == 1 && buf[0] == '1') {
free(cc_path);
@@ -2055,6 +2075,90 @@
return 0;
}
+static bool cgroup_read_from_file(const char *fn, char buf[], size_t bufsize)
+{
+ int ret = lxc_read_from_file(fn, buf, bufsize);
+ if (ret < 0) {
+ SYSERROR("failed to read %s", fn);
+ return false;
+ }
+ if (ret == bufsize) {
+ ERROR("too much data in %s", fn);
+ return false;
+ }
+ buf[ret] = '\0';
+ return true;
+}
+
+static bool do_init_cpuset_file(struct cgroup_mount_point *mp,
+ const char *path, const char *name)
+{
+ char value[128];
+ char *childfile, *parentfile, *tmp;
+ bool ok;
+
+ childfile = cgroup_to_absolute_path(mp, path, name);
+ if (!childfile)
+ return false;
+
+ /* don't overwrite a non-empty value in the file */
+ if (!cgroup_read_from_file(childfile, value, sizeof(value))) {
+ free(childfile);
+ return false;
+ }
+ if (value[0] != '\0' && value[0] != '\n') {
+ free(childfile);
+ return true;
+ }
+
+ /* path to the same name in the parent cgroup */
+ parentfile = strdup(path);
+ if (!parentfile)
+ return false;
+ tmp = strrchr(parentfile, '/');
+ if (!tmp) {
+ free(childfile);
+ free(parentfile);
+ return false;
+ }
+ if (tmp == parentfile)
+ tmp++; /* keep the '/' at the start */
+ *tmp = '\0';
+ tmp = parentfile;
+ parentfile = cgroup_to_absolute_path(mp, tmp, name);
+ free(tmp);
+ if (!parentfile) {
+ free(childfile);
+ return false;
+ }
+
+ /* copy from parent to child cgroup */
+ if (!cgroup_read_from_file(parentfile, value, sizeof(value))) {
+ free(parentfile);
+ free(childfile);
+ return false;
+ }
+ ok = (lxc_write_to_file(childfile, value, strlen(value), false) >= 0);
+ if (!ok)
+ SYSERROR("failed writing %s", childfile);
+ free(parentfile);
+ free(childfile);
+
+ return ok;
+}
+
+static bool init_cpuset_if_needed(struct cgroup_mount_point *mp,
+ const char *path)
+{
+ /* the files we have to handle here are only in cpuset hierarchies */
+ if (!lxc_string_in_array("cpuset",
+ (const char **)mp->hierarchy->subsystems))
+ return true;
+
+ return (do_init_cpuset_file(mp, path, "/cpuset.cpus") &&
+ do_init_cpuset_file(mp, path, "/cpuset.mems") );
+}
+
extern void lxc_monitor_send_state(const char *name, lxc_state_t state,
const char *lxcpath);
int do_unfreeze(int freeze, const char *name, const char *lxcpath)
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