[PATCH tip/core/rcu 8/8] torture: Affinity waiter tasks away from hotpluggable CPU

[Paul E. McKenney]

Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
 kernel/rcu/waketorture.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/kernel/rcu/waketorture.c b/kernel/rcu/waketorture.c
index f9843eb3f7b7..68be40400f51 100644
--- a/kernel/rcu/waketorture.c
+++ b/kernel/rcu/waketorture.c
@@ -236,7 +236,9 @@ static int wake_torture_waiter(void *arg)
  */
 static int wake_torture_onoff(void *args)
 {
+       cpumask_var_t cm;
        int cpu;
+       int i;
 
        VERBOSE_TOROUT_STRING("wake_torture_onoff task started");
        if (onoff_holdoff > 0) {
@@ -244,6 +246,11 @@ static int wake_torture_onoff(void *args)
                schedule_timeout_interruptible(onoff_holdoff * HZ);
                VERBOSE_TOROUT_STRING("wake_torture_onoff end holdoff");
        }
+
+       /*
+        * Find the last hotpluggable CPU, and affinity the waiter
+        * tasks elsewhere.
+        */
        for_each_online_cpu(cpu) {
                if (cpu_is_hotpluggable(cpu))
                        onoff_cpu = cpu;
@@ -257,6 +264,18 @@ static int wake_torture_onoff(void *args)
                }
        }
        pr_alert("%s" TORTURE_FLAG " wake_torture_onoff: onoff_cpu: %d\n", 
torture_type, onoff_cpu);
+       if (!zalloc_cpumask_var(&cm, GFP_KERNEL)) {
+               VERBOSE_TOROUT_STRING("wake_torture_onoff: Out of memory, no 
affinity");
+       } else {
+               cpumask_copy(cm, cpu_online_mask);
+               cpumask_clear_cpu(onoff_cpu, cm);
+               if (cpumask_weight(cm) == 0)
+                       cpumask_setall(cm);
+               for (i = 0; i < nrealwaiters; i++)
+                       set_cpus_allowed_ptr(waiter_tasks[i], cm);
+       }
+
+       /* Cycle the victim CPU online and offline! */
        while (!torture_must_stop() && onoff_cpu >= 0) {
                if (!torture_offline(onoff_cpu,
                                    &n_offline_attempts, &n_offline_successes,
-- 
2.5.2