cpuset: cleanup cpuset[_can]_attach()
cpuset_can_attach() prepare global variables cpus_attach and
cpuset_attach_nodemask_{to|from} which are used by cpuset_attach().
There is no reason to prepare in cpuset_can_attach(). The same
information can be accessed from cpuset_attach().
Move the prepartion logic from cpuset_can_attach() to cpuset_attach()
and make the global variables static ones inside cpuset_attach().
With this change, there's no reason to keep
cpuset_attach_nodemask_{from|to} global. Move them inside
cpuset_attach(). Unfortunately, we need to keep cpus_attach global as
it can't be allocated from cpuset_attach().
v2: cpus_attach not converted to cpumask_t as per Li Zefan and Rusty
Russell.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4b054b9..c5edc6b 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1395,15 +1395,6 @@
return val;
}
-/*
- * Protected by cgroup_lock. The nodemasks must be stored globally because
- * dynamically allocating them is not allowed in can_attach, and they must
- * persist until attach.
- */
-static cpumask_var_t cpus_attach;
-static nodemask_t cpuset_attach_nodemask_from;
-static nodemask_t cpuset_attach_nodemask_to;
-
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
@@ -1430,6 +1421,28 @@
return ret;
}
+ return 0;
+}
+
+/*
+ * Protected by cgroup_mutex. cpus_attach is used only by cpuset_attach()
+ * but we can't allocate it dynamically there. Define it global and
+ * allocate from cpuset_init().
+ */
+static cpumask_var_t cpus_attach;
+
+static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
+{
+ /* static bufs protected by cgroup_mutex */
+ static nodemask_t cpuset_attach_nodemask_from;
+ static nodemask_t cpuset_attach_nodemask_to;
+ struct mm_struct *mm;
+ struct task_struct *task;
+ struct task_struct *leader = cgroup_taskset_first(tset);
+ struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
+ struct cpuset *cs = cgroup_cs(cgrp);
+ struct cpuset *oldcs = cgroup_cs(oldcgrp);
+
/* prepare for attach */
if (cs == &top_cpuset)
cpumask_copy(cpus_attach, cpu_possible_mask);
@@ -1438,18 +1451,6 @@
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
- return 0;
-}
-
-static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
-{
- struct mm_struct *mm;
- struct task_struct *task;
- struct task_struct *leader = cgroup_taskset_first(tset);
- struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
- struct cpuset *cs = cgroup_cs(cgrp);
- struct cpuset *oldcs = cgroup_cs(oldcgrp);
-
cgroup_taskset_for_each(task, cgrp, tset) {
/*
* can_attach beforehand should guarantee that this doesn't