Merge tag 'char-misc-4.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregk...

[karo-tx-linux.git] / kernel / cgroup / cgroup.c

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 620794a20a339c7e10948da829fae5a6818e598b..df2e0f14a95d8e75ecbf424a0e308cc52d5b5eb2 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2006,6 +2006,8 @@ static void cgroup_migrate_add_task(struct task_struct *task,
        if (!cset->mg_src_cgrp)
                return;
 
+       mgctx->tset.nr_tasks++;
+
        list_move_tail(&task->cg_list, &cset->mg_tasks);
        if (list_empty(&cset->mg_node))
                list_add_tail(&cset->mg_node,
@@ -2094,21 +2096,19 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
        struct css_set *cset, *tmp_cset;
        int ssid, failed_ssid, ret;
 
-       /* methods shouldn't be called if no task is actually migrating */
-       if (list_empty(&tset->src_csets))
-               return 0;
-
        /* check that we can legitimately attach to the cgroup */
-       do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
-               if (ss->can_attach) {
-                       tset->ssid = ssid;
-                       ret = ss->can_attach(tset);
-                       if (ret) {
-                               failed_ssid = ssid;
-                               goto out_cancel_attach;
+       if (tset->nr_tasks) {
+               do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+                       if (ss->can_attach) {
+                               tset->ssid = ssid;
+                               ret = ss->can_attach(tset);
+                               if (ret) {
+                                       failed_ssid = ssid;
+                                       goto out_cancel_attach;
+                               }
                        }
-               }
-       } while_each_subsys_mask();
+               } while_each_subsys_mask();
+       }
 
        /*
         * Now that we're guaranteed success, proceed to move all tasks to
@@ -2137,25 +2137,29 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
         */
        tset->csets = &tset->dst_csets;
 
-       do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
-               if (ss->attach) {
-                       tset->ssid = ssid;
-                       ss->attach(tset);
-               }
-       } while_each_subsys_mask();
+       if (tset->nr_tasks) {
+               do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+                       if (ss->attach) {
+                               tset->ssid = ssid;
+                               ss->attach(tset);
+                       }
+               } while_each_subsys_mask();
+       }
 
        ret = 0;
        goto out_release_tset;
 
 out_cancel_attach:
-       do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
-               if (ssid == failed_ssid)
-                       break;
-               if (ss->cancel_attach) {
-                       tset->ssid = ssid;
-                       ss->cancel_attach(tset);
-               }
-       } while_each_subsys_mask();
+       if (tset->nr_tasks) {
+               do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+                       if (ssid == failed_ssid)
+                               break;
+                       if (ss->cancel_attach) {
+                               tset->ssid = ssid;
+                               ss->cancel_attach(tset);
+                       }
+               } while_each_subsys_mask();
+       }
 out_release_tset:
        spin_lock_irq(&css_set_lock);
        list_splice_init(&tset->dst_csets, &tset->src_csets);
@@ -2997,11 +3001,11 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
        cgrp->subtree_control &= ~disable;
 
        ret = cgroup_apply_control(cgrp);
-
        cgroup_finalize_control(cgrp, ret);
+       if (ret)
+               goto out_unlock;
 
        kernfs_activate(cgrp->kn);
-       ret = 0;
 out_unlock:
        cgroup_kn_unlock(of->kn);
        return ret ?: nbytes;
@@ -4669,6 +4673,10 @@ int __init cgroup_init(void)
 
                if (ss->bind)
                        ss->bind(init_css_set.subsys[ssid]);
+
+               mutex_lock(&cgroup_mutex);
+               css_populate_dir(init_css_set.subsys[ssid]);
+               mutex_unlock(&cgroup_mutex);
        }
 
        /* init_css_set.subsys[] has been updated, re-hash */