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blk-mq: Convert to new hotplug state machine

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Install the callbacks via the state machine so we can phase out the cpu
hotplug notifiers mess.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
Link: http://lkml.kernel.org/r/20160919212601.180033814@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Sebastian Andrzej Siewior 2016-09-22 08:05:19 -06:00 committed by Jens Axboe
parent 9467f85960
commit 65d5291eee
1 changed files with 43 additions and 44 deletions
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87
block/blk-mq.c
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@ -2116,50 +2116,18 @@ static void blk_mq_queue_reinit(struct request_queue *q,
blk_mq_sysfs_register(q);
}
static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
unsigned long action, void *hcpu)
/*
* New online cpumask which is going to be set in this hotplug event.
* Declare this cpumasks as global as cpu-hotplug operation is invoked
* one-by-one and dynamically allocating this could result in a failure.
*/
static struct cpumask cpuhp_online_new;
static void blk_mq_queue_reinit_work(void)
{
struct request_queue *q;
int cpu = (unsigned long)hcpu;
/*
* New online cpumask which is going to be set in this hotplug event.
* Declare this cpumasks as global as cpu-hotplug operation is invoked
* one-by-one and dynamically allocating this could result in a failure.
*/
static struct cpumask online_new;
/*
* Before hotadded cpu starts handling requests, new mappings must
* be established. Otherwise, these requests in hw queue might
* never be dispatched.
*
* For example, there is a single hw queue (hctx) and two CPU queues
* (ctx0 for CPU0, and ctx1 for CPU1).
*
* Now CPU1 is just onlined and a request is inserted into
* ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
* still zero.
*
* And then while running hw queue, flush_busy_ctxs() finds bit0 is
* set in pending bitmap and tries to retrieve requests in
* hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
* so the request in ctx1->rq_list is ignored.
*/
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DEAD:
case CPU_UP_CANCELED:
cpumask_copy(&online_new, cpu_online_mask);
break;
case CPU_UP_PREPARE:
cpumask_copy(&online_new, cpu_online_mask);
cpumask_set_cpu(cpu, &online_new);
break;
default:
return NOTIFY_OK;
}
mutex_lock(&all_q_mutex);
/*
* We need to freeze and reinit all existing queues. Freezing
* involves synchronous wait for an RCU grace period and doing it
@ -2180,13 +2148,43 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
}
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_queue_reinit(q, &online_new);
blk_mq_queue_reinit(q, &cpuhp_online_new);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_unfreeze_queue(q);
mutex_unlock(&all_q_mutex);
return NOTIFY_OK;
}
static int blk_mq_queue_reinit_dead(unsigned int cpu)
{
cpumask_clear_cpu(cpu, &cpuhp_online_new);
blk_mq_queue_reinit_work();
return 0;
}
/*
* Before hotadded cpu starts handling requests, new mappings must be
* established. Otherwise, these requests in hw queue might never be
* dispatched.
*
* For example, there is a single hw queue (hctx) and two CPU queues (ctx0
* for CPU0, and ctx1 for CPU1).
*
* Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
* and set bit0 in pending bitmap as ctx1->index_hw is still zero.
*
* And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
* pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
* But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
* is ignored.
*/
static int blk_mq_queue_reinit_prepare(unsigned int cpu)
{
cpumask_copy(&cpuhp_online_new, cpu_online_mask);
cpumask_set_cpu(cpu, &cpuhp_online_new);
blk_mq_queue_reinit_work();
return 0;
}
static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
@ -2391,8 +2389,9 @@ static int __init blk_mq_init(void)
cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
blk_mq_hctx_notify_dead);
hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
blk_mq_queue_reinit_prepare,
blk_mq_queue_reinit_dead);
return 0;
}
subsys_initcall(blk_mq_init);