1 files changed, 40 insertions, 28 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ced292d720b9..1b18090269ad 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -88,7 +88,7 @@ static DEFINE_MUTEX(cgroup_root_mutex);
 
 /*
  * Generate an array of cgroup subsystem pointers. At boot time, this is
- * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
+ * populated with the built in subsystems, and modular subsystems are
  * registered after that. The mutable section of this array is protected by
  * cgroup_mutex.
  */
@@ -1321,7 +1321,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
          * take duplicate reference counts on a subsystem that's already used,
          * but rebind_subsystems handles this case.
          */
-        for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+        for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                 unsigned long bit = 1UL << i;
 
                 if (!(bit & opts->subsys_mask))
@@ -1337,7 +1337,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
                  * raced with a module_delete call, and to the user this is
                  * essentially a "subsystem doesn't exist" case.
                  */
-                for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) {
+                for (i--; i >= 0; i--) {
                         /* drop refcounts only on the ones we took */
                         unsigned long bit = 1UL << i;
 
@@ -1354,7 +1354,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 static void drop_parsed_module_refcounts(unsigned long subsys_mask)
 {
         int i;
-        for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+        for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                 unsigned long bit = 1UL << i;
 
                 if (!(bit & subsys_mask))
@@ -4442,8 +4442,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
          * since cgroup_init_subsys will have already taken care of it.
          */
         if (ss->module == NULL) {
-                /* a few sanity checks */
-                BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT);
+                /* a sanity check */
                 BUG_ON(subsys[ss->subsys_id] != ss);
                 return 0;
         }
@@ -4457,7 +4456,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
          */
         mutex_lock(&cgroup_mutex);
         /* find the first empty slot in the array */
-        for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+        for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                 if (subsys[i] == NULL)
                         break;
         }
@@ -4560,7 +4559,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
 
         mutex_lock(&cgroup_mutex);
         /* deassign the subsys_id */
-        BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT);
         subsys[ss->subsys_id] = NULL;
 
         /* remove subsystem from rootnode's list of subsystems */
@@ -4623,10 +4621,13 @@ int __init cgroup_init_early(void)
         for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
                 INIT_HLIST_HEAD(&css_set_table[i]);
 
-        /* at bootup time, we don't worry about modular subsystems */
-        for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+        for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                 struct cgroup_subsys *ss = subsys[i];
 
+                /* at bootup time, we don't worry about modular subsystems */
+                if (!ss || ss->module)
+                        continue;
+
                 BUG_ON(!ss->name);
                 BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
                 BUG_ON(!ss->create);
@@ -4659,9 +4660,12 @@ int __init cgroup_init(void)
         if (err)
                 return err;
 
-        /* at bootup time, we don't worry about modular subsystems */
-        for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+        for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                 struct cgroup_subsys *ss = subsys[i];
+
+                /* at bootup time, we don't worry about modular subsystems */
+                if (!ss || ss->module)
+                        continue;
                 if (!ss->early_init)
                         cgroup_init_subsys(ss);
                 if (ss->use_id)
@@ -4856,13 +4860,16 @@ void cgroup_fork_callbacks(struct task_struct *child)
 {
         if (need_forkexit_callback) {
                 int i;
-                /*
-                 * forkexit callbacks are only supported for builtin
-                 * subsystems, and the builtin section of the subsys array is
-                 * immutable, so we don't need to lock the subsys array here.
-                 */
-                for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+                for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                         struct cgroup_subsys *ss = subsys[i];
+
+                        /*
+                         * forkexit callbacks are only supported for
+                         * builtin subsystems.
+                         */
+                        if (!ss || ss->module)
+                                continue;
+
                         if (ss->fork)
                                 ss->fork(child);
                 }
@@ -4967,12 +4974,13 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
         tsk->cgroups = &init_css_set;
 
         if (run_callbacks && need_forkexit_callback) {
-                /*
-                 * modular subsystems can't use callbacks, so no need to lock
-                 * the subsys array
-                 */
-                for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+                for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                         struct cgroup_subsys *ss = subsys[i];
+
+                        /* modular subsystems can't use callbacks */
+                        if (!ss || ss->module)
+                                continue;
+
                         if (ss->exit) {
                                 struct cgroup *old_cgrp =
                                         rcu_dereference_raw(cg->subsys[i])->cgroup;
@@ -5158,13 +5166,17 @@ static int __init cgroup_disable(char *str)
         while ((token = strsep(&str, ",")) != NULL) {
                 if (!*token)
                         continue;
-                /*
-                 * cgroup_disable, being at boot time, can't know about module
-                 * subsystems, so we don't worry about them.
-                 */
-                for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+                for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
                         struct cgroup_subsys *ss = subsys[i];
 
+                        /*
+                         * cgroup_disable, being at boot time, can't
+                         * know about module subsystems, so we don't
+                         * worry about them.
+                         */
+                        if (!ss || ss->module)
+                                continue;
+
                         if (!strcmp(token, ss->name)) {
                                 ss->disabled = 1;
                                 printk(KERN_INFO "Disabling %s control group"