cpuset: cleanup guarantee_online_{cpus|mems}()

- We never pass a NULL @cs to these functions.
- The top cpuset always has some online cpus/mems.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f0c884a..d753837 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -304,53 +304,38 @@ static struct file_system_type cpuset_fs_type = {
 /*
  * Return in pmask the portion of a cpusets's cpus_allowed that
  * are online.  If none are online, walk up the cpuset hierarchy
- * until we find one that does have some online cpus.  If we get
- * all the way to the top and still haven't found any online cpus,
- * return cpu_online_mask.  Or if passed a NULL cs from an exit'ing
- * task, return cpu_online_mask.
+ * until we find one that does have some online cpus.  The top
+ * cpuset always has some cpus online.
  *
  * One way or another, we guarantee to return some non-empty subset
  * of cpu_online_mask.
  *
  * Call with callback_mutex held.
  */
-
 static void guarantee_online_cpus(const struct cpuset *cs,
                                  struct cpumask *pmask)
 {
-       while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
+       while (!cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
                cs = parent_cs(cs);
-       if (cs)
-               cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
-       else
-               cpumask_copy(pmask, cpu_online_mask);
-       BUG_ON(!cpumask_intersects(pmask, cpu_online_mask));
+       cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
 }
 
 /*
  * Return in *pmask the portion of a cpusets's mems_allowed that
  * are online, with memory.  If none are online with memory, walk
  * up the cpuset hierarchy until we find one that does have some
- * online mems.  If we get all the way to the top and still haven't
- * found any online mems, return node_states[N_MEMORY].
+ * online mems.  The top cpuset always has some mems online.
  *
  * One way or another, we guarantee to return some non-empty subset
  * of node_states[N_MEMORY].
  *
  * Call with callback_mutex held.
  */
-
 static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
 {
-       while (cs && !nodes_intersects(cs->mems_allowed,
-                                       node_states[N_MEMORY]))
+       while (!nodes_intersects(cs->mems_allowed, node_states[N_MEMORY]))
                cs = parent_cs(cs);
-       if (cs)
-               nodes_and(*pmask, cs->mems_allowed,
-                                       node_states[N_MEMORY]);
-       else
-               *pmask = node_states[N_MEMORY];
-       BUG_ON(!nodes_intersects(*pmask, node_states[N_MEMORY]));
+       nodes_and(*pmask, cs->mems_allowed, node_states[N_MEMORY]);
 }
 
 /*