1 files changed, 55 insertions, 0 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d65a1246829f..ca38db223f84 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -44,6 +44,9 @@
 #include <linux/string.h>
 #include <linux/sort.h>
 #include <linux/kmod.h>
+#include <linux/delayacct.h>
+#include <linux/cgroupstats.h>
+
 #include <asm/atomic.h>
 
 static DEFINE_MUTEX(cgroup_mutex);
@@ -1766,6 +1769,58 @@ static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cont)
         return n;
 }
 
+/**
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ *
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+        int ret = -EINVAL;
+        struct cgroup *cont;
+        struct cgroup_iter it;
+        struct task_struct *tsk;
+        /*
+         * Validate dentry by checking the superblock operations
+         */
+        if (dentry->d_sb->s_op != &cgroup_ops)
+                 goto err;
+
+        ret = 0;
+        cont = dentry->d_fsdata;
+        rcu_read_lock();
+
+        cgroup_iter_start(cont, &it);
+        while ((tsk = cgroup_iter_next(cont, &it))) {
+                switch (tsk->state) {
+                case TASK_RUNNING:
+                        stats->nr_running++;
+                        break;
+                case TASK_INTERRUPTIBLE:
+                        stats->nr_sleeping++;
+                        break;
+                case TASK_UNINTERRUPTIBLE:
+                        stats->nr_uninterruptible++;
+                        break;
+                case TASK_STOPPED:
+                        stats->nr_stopped++;
+                        break;
+                default:
+                        if (delayacct_is_task_waiting_on_io(tsk))
+                                stats->nr_io_wait++;
+                        break;
+                }
+        }
+        cgroup_iter_end(cont, &it);
+
+        rcu_read_unlock();
+err:
+        return ret;
+}
+
 static int cmppid(const void *a, const void *b)
 {
         return *(pid_t *)a - *(pid_t *)b;