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>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8912407a4dd0edb251a36e3befe3ff8182598bdf..aae8064fd9e6fbd3409eb37f43fbac84d48ca67a 100644 (file)
--- 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);
 }
 

diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 517d4b68a1befcad9e4b383c0ed077133d25b3b3..57ec49f0839e53d18281fb7622497d446115dcc0 100644 (file)
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -512,9 +512,7 @@ struct r5conf {
        } __percpu *percpu;
        int scribble_disks;
        int scribble_sectors;
-#ifdef CONFIG_HOTPLUG_CPU
-       struct notifier_block   cpu_notify;
-#endif
+       struct hlist_node node;
 
        /*
         * Free stripes pool

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 332b39c21d2ea15cc1b14e2cd80697256c011952..4066c74bb73c12b40519dda9eb0a65c2c1b45b3a 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -27,6 +27,7 @@ enum cpuhp_state {
        CPUHP_SMPCFD_PREPARE,
        CPUHP_RELAY_PREPARE,
        CPUHP_SLAB_PREPARE,
+       CPUHP_MD_RAID5_PREPARE,
        CPUHP_RCUTREE_PREP,
        CPUHP_NOTIFY_PREPARE,
        CPUHP_TIMERS_DEAD,