/* let's not notify more than 100 times per second */
#define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100)
+/*
+ * To avoid confusing the compiler (and generating warnings) with code
+ * that attempts to access what would be a 0-element array (i.e. sized
+ * to a potentially empty array when CGROUP_SUBSYS_COUNT == 0), this
+ * constant expression can be added.
+ */
+#define CGROUP_HAS_SUBSYS_CONFIG (CGROUP_SUBSYS_COUNT > 0)
+
/*
* cgroup_mutex is the master lock. Any modification to cgroup or its
* hierarchy must be performed while holding it.
*/
bool cgroup_ssid_enabled(int ssid)
{
- if (CGROUP_SUBSYS_COUNT == 0)
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
return false;
return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
struct cgroup_subsys *ss)
{
- if (ss)
+ if (CGROUP_HAS_SUBSYS_CONFIG && ss)
return rcu_dereference_check(cgrp->subsys[ss->id],
lockdep_is_held(&cgroup_mutex));
else
{
struct cgroup_subsys_state *css;
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
+ return NULL;
+
do {
css = cgroup_css(cgrp, ss);
{
struct cgroup_subsys_state *css;
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
+ return NULL;
+
rcu_read_lock();
do {
* the matching css from the cgroup's subsys table is guaranteed to
* be and stay valid until the enclosing operation is complete.
*/
- if (cft->ss)
+ if (CGROUP_HAS_SUBSYS_CONFIG && cft->ss)
return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
else
return &cgrp->self;
*/
#define do_each_subsys_mask(ss, ssid, ss_mask) do { \
unsigned long __ss_mask = (ss_mask); \
- if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
+ if (!CGROUP_HAS_SUBSYS_CONFIG) { \
(ssid) = 0; \
break; \
} \
struct css_set *cset = tset->cur_cset;
struct task_struct *task = tset->cur_task;
- while (&cset->mg_node != tset->csets) {
+ while (CGROUP_HAS_SUBSYS_CONFIG && &cset->mg_node != tset->csets) {
if (!task)
task = list_first_entry(&cset->mg_tasks,
struct task_struct, cg_list);
it->ss = css->ss;
it->flags = flags;
- if (it->ss)
+ if (CGROUP_HAS_SUBSYS_CONFIG && it->ss)
it->cset_pos = &css->cgroup->e_csets[css->ss->id];
else
it->cset_pos = &css->cgroup->cset_links;