Merge tag 'pci-v4.4-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

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

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b316debadeb3e5f7a77351fe8c218be2b08802f6..470f6536b9e8cfb029eedb5ecdb3c3e8c3c341be 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -760,9 +760,11 @@ static void put_css_set_locked(struct css_set *cset)
        if (!atomic_dec_and_test(&cset->refcount))
                return;
 
-       /* This css_set is dead. unlink it and release cgroup refcounts */
-       for_each_subsys(ss, ssid)
+       /* This css_set is dead. unlink it and release cgroup and css refs */
+       for_each_subsys(ss, ssid) {
                list_del(&cset->e_cset_node[ssid]);
+               css_put(cset->subsys[ssid]);
+       }
        hash_del(&cset->hlist);
        css_set_count--;
 
@@ -1062,9 +1064,13 @@ static struct css_set *find_css_set(struct css_set *old_cset,
        key = css_set_hash(cset->subsys);
        hash_add(css_set_table, &cset->hlist, key);
 
-       for_each_subsys(ss, ssid)
+       for_each_subsys(ss, ssid) {
+               struct cgroup_subsys_state *css = cset->subsys[ssid];
+
                list_add_tail(&cset->e_cset_node[ssid],
-                             &cset->subsys[ssid]->cgroup->e_csets[ssid]);
+                             &css->cgroup->e_csets[ssid]);
+               css_get(css);
+       }
 
        spin_unlock_bh(&css_set_lock);
 
@@ -2231,6 +2237,9 @@ struct cgroup_taskset {
        struct list_head        src_csets;
        struct list_head        dst_csets;
 
+       /* the subsys currently being processed */
+       int                     ssid;
+
        /*
         * Fields for cgroup_taskset_*() iteration.
         *
@@ -2293,25 +2302,29 @@ static void cgroup_taskset_add(struct task_struct *task,
 /**
  * cgroup_taskset_first - reset taskset and return the first task
  * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
  *
  * @tset iteration is initialized and the first task is returned.
  */
-struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
+                                        struct cgroup_subsys_state **dst_cssp)
 {
        tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
        tset->cur_task = NULL;
 
-       return cgroup_taskset_next(tset);
+       return cgroup_taskset_next(tset, dst_cssp);
 }
 
 /**
  * cgroup_taskset_next - iterate to the next task in taskset
  * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
  *
  * Return the next task in @tset.  Iteration must have been initialized
  * with cgroup_taskset_first().
  */
-struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
+                                       struct cgroup_subsys_state **dst_cssp)
 {
        struct css_set *cset = tset->cur_cset;
        struct task_struct *task = tset->cur_task;
@@ -2326,6 +2339,18 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
                if (&task->cg_list != &cset->mg_tasks) {
                        tset->cur_cset = cset;
                        tset->cur_task = task;
+
+                       /*
+                        * This function may be called both before and
+                        * after cgroup_taskset_migrate().  The two cases
+                        * can be distinguished by looking at whether @cset
+                        * has its ->mg_dst_cset set.
+                        */
+                       if (cset->mg_dst_cset)
+                               *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
+                       else
+                               *dst_cssp = cset->subsys[tset->ssid];
+
                        return task;
                }
 
@@ -2361,7 +2386,8 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
        /* check that we can legitimately attach to the cgroup */
        for_each_e_css(css, i, dst_cgrp) {
                if (css->ss->can_attach) {
-                       ret = css->ss->can_attach(css, tset);
+                       tset->ssid = i;
+                       ret = css->ss->can_attach(tset);
                        if (ret) {
                                failed_css = css;
                                goto out_cancel_attach;
@@ -2394,9 +2420,12 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
         */
        tset->csets = &tset->dst_csets;
 
-       for_each_e_css(css, i, dst_cgrp)
-               if (css->ss->attach)
-                       css->ss->attach(css, tset);
+       for_each_e_css(css, i, dst_cgrp) {
+               if (css->ss->attach) {
+                       tset->ssid = i;
+                       css->ss->attach(tset);
+               }
+       }
 
        ret = 0;
        goto out_release_tset;
@@ -2405,8 +2434,10 @@ out_cancel_attach:
        for_each_e_css(css, i, dst_cgrp) {
                if (css == failed_css)
                        break;
-               if (css->ss->cancel_attach)
-                       css->ss->cancel_attach(css, tset);
+               if (css->ss->cancel_attach) {
+                       tset->ssid = i;
+                       css->ss->cancel_attach(tset);
+               }
        }
 out_release_tset:
        spin_lock_bh(&css_set_lock);