1 files changed, 81 insertions, 14 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5d5e107ebc4e..39d6354af489 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6376,26 +6376,31 @@ error:
         return -ENOMEM;
 #endif
 }
+
+static cpumask_t *doms_cur;     /* current sched domains */
+static int ndoms_cur;           /* number of sched domains in 'doms_cur' */
+
+/*
+ * Special case: If a kmalloc of a doms_cur partition (array of
+ * cpumask_t) fails, then fallback to a single sched domain,
+ * as determined by the single cpumask_t fallback_doms.
+ */
+static cpumask_t fallback_doms;
+
 /*
  * Set up scheduler domains and groups.  Callers must hold the hotplug lock.
+ * For now this just excludes isolated cpus, but could be used to
+ * exclude other special cases in the future.
  */
 static int arch_init_sched_domains(const cpumask_t *cpu_map)
 {
-        cpumask_t cpu_default_map;
-        int err;
-
-        /*
-         * Setup mask for cpus without special case scheduling requirements.
-         * For now this just excludes isolated cpus, but could be used to
-         * exclude other special cases in the future.
-         */
-        cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
-
-        err = build_sched_domains(&cpu_default_map);
-
+        ndoms_cur = 1;
+        doms_cur = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
+        if (!doms_cur)
+                doms_cur = &fallback_doms;
+        cpus_andnot(*doms_cur, *cpu_map, cpu_isolated_map);
         register_sched_domain_sysctl();
-
-        return err;
+        return build_sched_domains(doms_cur);
 }
 
 static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
@@ -6419,6 +6424,68 @@ static void detach_destroy_domains(const cpumask_t *cpu_map)
         arch_destroy_sched_domains(cpu_map);
 }
 
+/*
+ * Partition sched domains as specified by the 'ndoms_new'
+ * cpumasks in the array doms_new[] of cpumasks.  This compares
+ * doms_new[] to the current sched domain partitioning, doms_cur[].
+ * It destroys each deleted domain and builds each new domain.
+ *
+ * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
+ * The masks don't intersect (don't overlap.)  We should setup one
+ * sched domain for each mask.  CPUs not in any of the cpumasks will
+ * not be load balanced.  If the same cpumask appears both in the
+ * current 'doms_cur' domains and in the new 'doms_new', we can leave
+ * it as it is.
+ *
+ * The passed in 'doms_new' should be kmalloc'd.  This routine takes
+ * ownership of it and will kfree it when done with it.  If the caller
+ * failed the kmalloc call, then it can pass in doms_new == NULL,
+ * and partition_sched_domains() will fallback to the single partition
+ * 'fallback_doms'.
+ *
+ * Call with hotplug lock held
+ */
+void partition_sched_domains(int ndoms_new, cpumask_t *doms_new)
+{
+        int i, j;
+
+        if (doms_new == NULL) {
+                ndoms_new = 1;
+                doms_new = &fallback_doms;
+                cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map);
+        }
+
+        /* Destroy deleted domains */
+        for (i = 0; i < ndoms_cur; i++) {
+                for (j = 0; j < ndoms_new; j++) {
+                        if (cpus_equal(doms_cur[i], doms_new[j]))
+                                goto match1;
+                }
+                /* no match - a current sched domain not in new doms_new[] */
+                detach_destroy_domains(doms_cur + i);
+match1:
+                ;
+        }
+
+        /* Build new domains */
+        for (i = 0; i < ndoms_new; i++) {
+                for (j = 0; j < ndoms_cur; j++) {
+                        if (cpus_equal(doms_new[i], doms_cur[j]))
+                                goto match2;
+                }
+                /* no match - add a new doms_new */
+                build_sched_domains(doms_new + i);
+match2:
+                ;
+        }
+
+        /* Remember the new sched domains */
+        if (doms_cur != &fallback_doms)
+                kfree(doms_cur);
+        doms_cur = doms_new;
+        ndoms_cur = ndoms_new;
+}
+
 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 static int arch_reinit_sched_domains(void)
 {