softirq: Revert "softirq: Do not create hrtimer softirq thread..."

This reverts commit d69c5d37. The
softirq is necessary even in the CONFIG_HIGH_RES_TIMERS=n case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/softirq.c

@@ -1161,8 +1161,6 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 			per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
 		}
 		for (i = 0; i < NR_SOFTIRQS; i++) {
-			if (!softirq_names[i])
-				continue;
 			p = kthread_create(ksoftirqd,
 					   &per_cpu(ksoftirqd, hotcpu)[i],
 					   "sirq-%s/%d", softirq_names[i],
@@ -1179,11 +1177,8 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 	break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
-		for (i = 0; i < NR_SOFTIRQS; i++) {
-			p = per_cpu(ksoftirqd, hotcpu)[i].tsk;
-			if (p)
-				wake_up_process(p);
-		}
+		for (i = 0; i < NR_SOFTIRQS; i++)
+			wake_up_process(per_cpu(ksoftirqd, hotcpu)[i].tsk);
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_UP_CANCELED:
@@ -1197,11 +1192,9 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
 		for (i = 0; i < NR_SOFTIRQS; i++) {
 			param.sched_priority = MAX_RT_PRIO-1;
 			p = per_cpu(ksoftirqd, hotcpu)[i].tsk;
-			if (p) {
-				sched_setscheduler(p, SCHED_FIFO, &param);
-				per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
-				kthread_stop(p);
-			}
+			sched_setscheduler(p, SCHED_FIFO, &param);
+			per_cpu(ksoftirqd, hotcpu)[i].tsk = NULL;
+			kthread_stop(p);
 		}
 		takeover_tasklets(hotcpu);
 		break;