cpuset: clean up cpuset hierarchy traversal code

Use cpuset.stack_list rather than kfifo, so we avoid memory allocation
for kfifo.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 13 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7a82e9033a7f..d5ab79cf516d 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -54,7 +54,6 @@
 #include <asm/uaccess.h>
 #include <asm/atomic.h>
 #include <linux/mutex.h>
-#include <linux/kfifo.h>
 #include <linux/workqueue.h>
 #include <linux/cgroup.h>
 
@@ -557,7 +556,7 @@ update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
  * So the reverse nesting would risk an ABBA deadlock.
  *
  * The three key local variables below are:
- *    q  - a kfifo queue of cpuset pointers, used to implement a
+ *    q  - a linked-list queue of cpuset pointers, used to implement a
  *         top-down scan of all cpusets.  This scan loads a pointer
  *         to each cpuset marked is_sched_load_balance into the
  *         array 'csa'.  For our purposes, rebuilding the schedulers
@@ -592,7 +591,7 @@ update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
 
 void rebuild_sched_domains(void)
 {
-        struct kfifo *q;        /* queue of cpusets to be scanned */
+        LIST_HEAD(q);           /* queue of cpusets to be scanned*/
         struct cpuset *cp;      /* scans q */
         struct cpuset **csa;    /* array of all cpuset ptrs */
         int csn;                /* how many cpuset ptrs in csa so far */
@@ -602,7 +601,6 @@ void rebuild_sched_domains(void)
         int ndoms;              /* number of sched domains in result */
         int nslot;              /* next empty doms[] cpumask_t slot */
 
-        q = NULL;
         csa = NULL;
         doms = NULL;
         dattr = NULL;
@@ -622,20 +620,19 @@ void rebuild_sched_domains(void)
                 goto rebuild;
         }
 
-        q = kfifo_alloc(number_of_cpusets * sizeof(cp), GFP_KERNEL, NULL);
-        if (IS_ERR(q))
-                goto done;
         csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
         if (!csa)
                 goto done;
         csn = 0;
 
-        cp = &top_cpuset;
-        __kfifo_put(q, (void *)&cp, sizeof(cp));
-        while (__kfifo_get(q, (void *)&cp, sizeof(cp))) {
+        list_add(&top_cpuset.stack_list, &q);
+        while (!list_empty(&q)) {
                 struct cgroup *cont;
                 struct cpuset *child;   /* scans child cpusets of cp */
 
+                cp = list_first_entry(&q, struct cpuset, stack_list);
+                list_del(q.next);
+
                 if (cpus_empty(cp->cpus_allowed))
                         continue;
 
@@ -652,7 +649,7 @@ void rebuild_sched_domains(void)
 
                 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
                         child = cgroup_cs(cont);
-                        __kfifo_put(q, (void *)&child, sizeof(cp));
+                        list_add_tail(&child->stack_list, &q);
                 }
         }
 
@@ -735,8 +732,6 @@ rebuild:
         put_online_cpus();
 
 done:
-        if (q && !IS_ERR(q))
-                kfifo_free(q);
         kfree(csa);
         /* Don't kfree(doms) -- partition_sched_domains() does that. */
         /* Don't kfree(dattr) -- partition_sched_domains() does that. */