block/softirq: Convert to hotplug state machine

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-9-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 11 insertions, 17 deletions

diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 53b1737e978d..96631e6a22b9 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -78,30 +78,21 @@ static int raise_blk_irq(int cpu, struct request *rq)
 }
 #endif
 
-static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
-                          void *hcpu)
+static int blk_softirq_cpu_dead(unsigned int cpu)
 {
         /*
          * If a CPU goes away, splice its entries to the current CPU
          * and trigger a run of the softirq
          */
-        if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-                int cpu = (unsigned long) hcpu;
-
-                local_irq_disable();
-                list_splice_init(&per_cpu(blk_cpu_done, cpu),
-                                 this_cpu_ptr(&blk_cpu_done));
-                raise_softirq_irqoff(BLOCK_SOFTIRQ);
-                local_irq_enable();
-        }
+        local_irq_disable();
+        list_splice_init(&per_cpu(blk_cpu_done, cpu),
+                         this_cpu_ptr(&blk_cpu_done));
+        raise_softirq_irqoff(BLOCK_SOFTIRQ);
+        local_irq_enable();
 
-        return NOTIFY_OK;
+        return 0;
 }
 
-static struct notifier_block blk_cpu_notifier = {
-        .notifier_call  = blk_cpu_notify,
-};
-
 void __blk_complete_request(struct request *req)
 {
         int ccpu, cpu;
@@ -180,7 +171,9 @@ static __init int blk_softirq_init(void)
                 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
 
         open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
-        register_hotcpu_notifier(&blk_cpu_notifier);
+        cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
+                                  "block/softirq:dead", NULL,
+                                  blk_softirq_cpu_dead);
         return 0;
 }
 subsys_initcall(blk_softirq_init);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 2ca7b34871e0..d4274d51fe27 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -23,6 +23,7 @@ enum cpuhp_state {
         CPUHP_ARM64_FPSIMD_DEAD,
         CPUHP_ARM_OMAP_WAKE_DEAD,
         CPUHP_IRQ_POLL_DEAD,
+        CPUHP_BLOCK_SOFTIRQ_DEAD,
         CPUHP_WORKQUEUE_PREP,
         CPUHP_POWER_NUMA_PREPARE,
         CPUHP_HRTIMERS_PREPARE,