Re: [PATCH 4/4] cgroup: remove extra calls to find_existing_css_set
From: Li Zefan <hidden>
Date: 2011-12-22 05:48:38
Also in:
lkml
quoted hunk ↗ jump to hunk
@@ -2091,6 +2010,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) * rcu or tasklist locked. instead, build an array of all threads in the * group - group_rwsem prevents new threads from appearing, and if * threads exit, this will just be an over-estimate. + * + * While creating the list, also make sure css_sets exist for all + * threads to be migrated. we use find_css_set, which allocates a new + * one if necessary. */ group_size = get_nr_threads(leader); /* flex_array supports very large thread-groups better than kmalloc. */@@ -2137,6 +2060,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* nothing to do if this task is already in the cgroup */ if (ent.cgrp == cgrp) continue; + ent.cg = find_css_set(tsk->cgroups, cgrp);
unfortunately This won't work, because we are holding tasklist_lock.
+ if (!ent.cg) {
+ retval = -ENOMEM;
+ group_size = i;
+ goto out_list_teardown;
+ }
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;