[PATCH 09/16] md: raid5: Convert to hotplug state machine

From: Sebastian Andrzej Siewior
Date: Thu Aug 18 2016 - 08:58:34 EST


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

Cc: Neil Brown <neilb@xxxxxxxx>
Cc: linux-raid@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
drivers/md/raid5.c | 83 ++++++++++++++++------------------------------
drivers/md/raid5.h | 4 +--
include/linux/cpuhotplug.h | 1 +
3 files changed, 30 insertions(+), 58 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f79b1a57f69a..40ac4c953ff2 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6344,22 +6344,20 @@ static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu
return 0;
}

+static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
+{
+ 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)
{
- unsigned long cpu;
-
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);
}

@@ -6378,64 +6376,28 @@ 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);
@@ -7967,10 +7929,20 @@ 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);
@@ -7982,6 +7954,7 @@ 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 517d4b68a1be..57ec49f0839e 100644
--- 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 332b39c21d2e..5811954809af 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -28,6 +28,7 @@ enum cpuhp_state {
CPUHP_RELAY_PREPARE,
CPUHP_SLAB_PREPARE,
CPUHP_RCUTREE_PREP,
+ CPUHP_MD_RAID5_PREPARE,
CPUHP_NOTIFY_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_BRINGUP_CPU,
--
2.9.3