cpumask: Simplify sched_rt.c

find_lowest_rq() wants to call pick_optimal_cpu() on the
intersection of sched_domain_span(sd) and lowest_mask.  Rather
than doing a cpus_and into a temporary, we can open-code it.

This actually makes the code slightly clearer, IMHO.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <200911031453.15350.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 24 insertions, 37 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index a4d790cddb19..5c5fef378415 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1153,29 +1153,12 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
 
 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
 
-static inline int pick_optimal_cpu(int this_cpu,
-                                   const struct cpumask *mask)
-{
-        int first;
-
-        /* "this_cpu" is cheaper to preempt than a remote processor */
-        if ((this_cpu != -1) && cpumask_test_cpu(this_cpu, mask))
-                return this_cpu;
-
-        first = cpumask_first(mask);
-        if (first < nr_cpu_ids)
-                return first;
-
-        return -1;
-}
-
 static int find_lowest_rq(struct task_struct *task)
 {
         struct sched_domain *sd;
         struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
         int this_cpu = smp_processor_id();
         int cpu      = task_cpu(task);
-        cpumask_var_t domain_mask;
 
         if (task->rt.nr_cpus_allowed == 1)
                 return -1; /* No other targets possible */
@@ -1198,28 +1181,26 @@ static int find_lowest_rq(struct task_struct *task)
          * Otherwise, we consult the sched_domains span maps to figure
          * out which cpu is logically closest to our hot cache data.
          */
-        if (this_cpu == cpu)
-                this_cpu = -1; /* Skip this_cpu opt if the same */
-
-        if (alloc_cpumask_var(&domain_mask, GFP_ATOMIC)) {
-                for_each_domain(cpu, sd) {
-                        if (sd->flags & SD_WAKE_AFFINE) {
-                                int best_cpu;
+        if (!cpumask_test_cpu(this_cpu, lowest_mask))
+                this_cpu = -1; /* Skip this_cpu opt if not among lowest */
 
-                                cpumask_and(domain_mask,
-                                            sched_domain_span(sd),
-                                            lowest_mask);
+        for_each_domain(cpu, sd) {
+                if (sd->flags & SD_WAKE_AFFINE) {
+                        int best_cpu;
 
-                                best_cpu = pick_optimal_cpu(this_cpu,
-                                                            domain_mask);
-
-                                if (best_cpu != -1) {
-                                        free_cpumask_var(domain_mask);
-                                        return best_cpu;
-                                }
-                        }
+                        /*
+                         * "this_cpu" is cheaper to preempt than a
+                         * remote processor.
+                         */
+                        if (this_cpu != -1 &&
+                            cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
+                                return this_cpu;
+
+                        best_cpu = cpumask_first_and(lowest_mask,
+                                                     sched_domain_span(sd));
+                        if (best_cpu < nr_cpu_ids)
+                                return best_cpu;
                 }
-                free_cpumask_var(domain_mask);
         }
 
         /*
@@ -1227,7 +1208,13 @@ static int find_lowest_rq(struct task_struct *task)
          * just give the caller *something* to work with from the compatible
          * locations.
          */
-        return pick_optimal_cpu(this_cpu, lowest_mask);
+        if (this_cpu != -1)
+                return this_cpu;
+
+        cpu = cpumask_any(lowest_mask);
+        if (cpu < nr_cpu_ids)
+                return cpu;
+        return -1;
 }
 
 /* Will lock the rq it finds */