[PATCH 20/21] blk: mq: cpu-notif: Convert to hotplug state machine

Sebastian Andrzej Siewior
2016-09-06T17:06:34Z

Install the callbacks via the state machine. The only currently handled
callback is CPU_DEAD and this one is converted.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
This patch against linux-next to take the block changes into account. It
depends on "blk: mq: reserve hotplug ID states for block"

block/blk-mq-cpu.c | 15 +++++++--------
block/blk-mq.c | 17 ++++-------------
block/blk-mq.h | 2 +-
include/linux/blk-mq.h | 2 +-
4 files changed, 13 insertions(+), 23 deletions(-)

--- a/block/blk-mq-cpu.c
+++ b/block/blk-mq-cpu.c
@@ -18,18 +18,16 @@
static LIST_HEAD(blk_mq_cpu_notify_list);
static DEFINE_RAW_SPINLOCK(blk_mq_cpu_notify_lock);

-static int blk_mq_main_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+static int blk_mq_main_cpu_dead(unsigned int cpu)
{
- unsigned int cpu = (unsigned long) hcpu;
struct blk_mq_cpu_notifier *notify;
- int ret = NOTIFY_OK;
+ int ret;

raw_spin_lock(&blk_mq_cpu_notify_lock);

list_for_each_entry(notify, &blk_mq_cpu_notify_list, list) {
- ret = notify->notify(notify->data, action, cpu);
- if (ret != NOTIFY_OK)
+ ret = notify->notify(notify->data, cpu);
+ if (ret)
break;
}

@@ -54,7 +52,7 @@ void blk_mq_unregister_cpu_notifier(stru
}

void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
- int (*fn)(void *, unsigned long, unsigned int),
+ int (*fn)(void *, unsigned int),
void *data)
{
notifier->notify = fn;
@@ -63,5 +61,6 @@ void blk_mq_init_cpu_notifier(struct blk

void __init blk_mq_cpu_init(void)
{
- hotcpu_notifier(blk_mq_main_cpu_notify, 0);
+ cpuhp_setup_state_nocalls(CPUHP_BLKMQ_DEAD, "block/mq:dead", NULL,
+ blk_mq_main_cpu_dead);
}
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1649,7 +1649,7 @@ static int blk_mq_hctx_cpu_offline(struc
spin_unlock(&ctx->lock);

if (list_empty(&tmp))
- return NOTIFY_OK;
+ return 0;

ctx = blk_mq_get_ctx(q);
spin_lock(&ctx->lock);
@@ -1669,23 +1669,14 @@ static int blk_mq_hctx_cpu_offline(struc

blk_mq_run_hw_queue(hctx, true);
blk_mq_put_ctx(ctx);
- return NOTIFY_OK;
+ return 0;
}

-static int blk_mq_hctx_notify(void *data, unsigned long action,
- unsigned int cpu)
+static int blk_mq_hctx_notify(void *data, unsigned int cpu)
{
struct blk_mq_hw_ctx *hctx = data;

- if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
- return blk_mq_hctx_cpu_offline(hctx, cpu);
-
- /*
- * In case of CPU online, tags may be reallocated
- * in blk_mq_map_swqueue() after mapping is updated.
- */
-
- return NOTIFY_OK;
+ return blk_mq_hctx_cpu_offline(hctx, cpu);
}

/* hctx->ctxs will be freed in queue's release handler */
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -36,7 +36,7 @@ void blk_mq_wake_waiters(struct request_
*/
struct blk_mq_cpu_notifier;
void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
- int (*fn)(void *, unsigned long, unsigned int),
+ int (*fn)(void *, unsigned int),
void *data);
void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier);
void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier);
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -9,7 +9,7 @@ struct blk_flush_queue;
struct blk_mq_cpu_notifier {
struct list_head list;
void *data;
- int (*notify)(void *data, unsigned long action, unsigned int cpu);
+ int (*notify)(void *data, unsigned int cpu);
};

struct blk_mq_ctxmap {