md/raid5: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Neil Brown <neilb@suse.com>
Cc: linux-raid@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-10-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 29 insertions, 55 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8912407a4dd0..aae8064fd9e6 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6330,22 +6330,20 @@ static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu
         return 0;
 }
 
-static void raid5_free_percpu(struct r5conf *conf)
+static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
 {
-        unsigned long cpu;
+        struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
+
+        free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
+        return 0;
+}
 
+static void raid5_free_percpu(struct r5conf *conf)
+{
         if (!conf->percpu)
                 return;
 
-#ifdef CONFIG_HOTPLUG_CPU
-        unregister_cpu_notifier(&conf->cpu_notify);
-#endif
-
-        get_online_cpus();
-        for_each_possible_cpu(cpu)
-                free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-        put_online_cpus();
-
+        cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
         free_percpu(conf->percpu);
 }
 
@@ -6364,64 +6362,28 @@ static void free_conf(struct r5conf *conf)
         kfree(conf);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
-                              void *hcpu)
+static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
 {
-        struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
-        long cpu = (long)hcpu;
+        struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
 
-        switch (action) {
-        case CPU_UP_PREPARE:
-        case CPU_UP_PREPARE_FROZEN:
-                if (alloc_scratch_buffer(conf, percpu)) {
-                        pr_err("%s: failed memory allocation for cpu%ld\n",
-                               __func__, cpu);
-                        return notifier_from_errno(-ENOMEM);
-                }
-                break;
-        case CPU_DEAD:
-        case CPU_DEAD_FROZEN:
-        case CPU_UP_CANCELED:
-        case CPU_UP_CANCELED_FROZEN:
-                free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-                break;
-        default:
-                break;
+        if (alloc_scratch_buffer(conf, percpu)) {
+                pr_err("%s: failed memory allocation for cpu%u\n",
+                       __func__, cpu);
+                return -ENOMEM;
         }
-        return NOTIFY_OK;
+        return 0;
 }
-#endif
 
 static int raid5_alloc_percpu(struct r5conf *conf)
 {
-        unsigned long cpu;
         int err = 0;
 
         conf->percpu = alloc_percpu(struct raid5_percpu);
         if (!conf->percpu)
                 return -ENOMEM;
 
-#ifdef CONFIG_HOTPLUG_CPU
-        conf->cpu_notify.notifier_call = raid456_cpu_notify;
-        conf->cpu_notify.priority = 0;
-        err = register_cpu_notifier(&conf->cpu_notify);
-        if (err)
-                return err;
-#endif
-
-        get_online_cpus();
-        for_each_present_cpu(cpu) {
-                err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-                if (err) {
-                        pr_err("%s: failed memory allocation for cpu%ld\n",
-                               __func__, cpu);
-                        break;
-                }
-        }
-        put_online_cpus();
-
+        err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
         if (!err) {
                 conf->scribble_disks = max(conf->raid_disks,
                         conf->previous_raid_disks);
@@ -7953,10 +7915,21 @@ static struct md_personality raid4_personality =
 
 static int __init raid5_init(void)
 {
+        int ret;
+
         raid5_wq = alloc_workqueue("raid5wq",
                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
         if (!raid5_wq)
                 return -ENOMEM;
+
+        ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
+                                      "md/raid5:prepare",
+                                      raid456_cpu_up_prepare,
+                                      raid456_cpu_dead);
+        if (ret) {
+                destroy_workqueue(raid5_wq);
+                return ret;
+        }
         register_md_personality(&raid6_personality);
         register_md_personality(&raid5_personality);
         register_md_personality(&raid4_personality);
@@ -7968,6 +7941,7 @@ static void raid5_exit(void)
         unregister_md_personality(&raid6_personality);
         unregister_md_personality(&raid5_personality);
         unregister_md_personality(&raid4_personality);
+        cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
         destroy_workqueue(raid5_wq);
 }