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>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7a82e9033a7f1f4dfc1cbfa9f14ae080bf5a7f41..d5ab79cf516d7edf77f8e45afe15c04cdae2cda4 100644 (file)
--- 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. */