[PATCH 08/21] block: softirq: Convert to hotplug state machine

[Sebastian Andrzej Siewior]

Install the callbacks via the state machine.

Cc: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 block/blk-softirq.c        | 27 ++++++++++-----------------
 include/linux/cpuhotplug.h |  1 +
 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 be6c01b7efbe..a12044828e03 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,
-- 
2.9.3