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Merge branch 'for-4.9/block-smp' of git://git.kernel.dk/linux-block

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Pull blk-mq CPU hotplug update from Jens Axboe:
 "This is the conversion of blk-mq to the new hotplug state machine"

* 'for-4.9/block-smp' of git://git.kernel.dk/linux-block:
  blk-mq: fixup "Convert to new hotplug state machine"
  blk-mq: Convert to new hotplug state machine
  blk-mq/cpu-notif: Convert to new hotplug state machine
This commit is contained in:
Linus Torvalds 2016-10-09 17:32:20 -07:00
commit 24532f7681
5 changed files with 58 additions and 149 deletions
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2
block/Makefile
View File

@ -6,7 +6,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
blk-lib.o blk-mq.o blk-mq-tag.o \
blk-mq-sysfs.o blk-mq-cpu.o blk-mq-cpumap.o ioctl.o \
blk-mq-sysfs.o blk-mq-cpumap.o ioctl.o \
genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
badblocks.o partitions/

67
block/blk-mq-cpu.c
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@ -1,67 +0,0 @@
/*
* CPU notifier helper code for blk-mq
*
* Copyright (C) 2013-2014 Jens Axboe
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/llist.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/blk-mq.h>
#include "blk-mq.h"
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)
{
unsigned int cpu = (unsigned long) hcpu;
struct blk_mq_cpu_notifier *notify;
int ret = NOTIFY_OK;
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)
break;
}
raw_spin_unlock(&blk_mq_cpu_notify_lock);
return ret;
}
void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
BUG_ON(!notifier->notify);
raw_spin_lock(&blk_mq_cpu_notify_lock);
list_add_tail(&notifier->list, &blk_mq_cpu_notify_list);
raw_spin_unlock(&blk_mq_cpu_notify_lock);
}
void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
raw_spin_lock(&blk_mq_cpu_notify_lock);
list_del(&notifier->list);
raw_spin_unlock(&blk_mq_cpu_notify_lock);
}
void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
int (*fn)(void *, unsigned long, unsigned int),
void *data)
{
notifier->notify = fn;
notifier->data = data;
}
void __init blk_mq_cpu_init(void)
{
hotcpu_notifier(blk_mq_main_cpu_notify, 0);
}

123
block/blk-mq.c
View File

@ -1563,11 +1563,13 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
* software queue to the hw queue dispatch list, and ensure that it
* gets run.
*/
static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
LIST_HEAD(tmp);
hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
ctx = __blk_mq_get_ctx(hctx->queue, cpu);
spin_lock(&ctx->lock);
@ -1578,30 +1580,20 @@ static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
spin_unlock(&ctx->lock);
if (list_empty(&tmp))
return NOTIFY_OK;
return 0;
spin_lock(&hctx->lock);
list_splice_tail_init(&tmp, &hctx->dispatch);
spin_unlock(&hctx->lock);
blk_mq_run_hw_queue(hctx, true);
return NOTIFY_OK;
return 0;
}
static int blk_mq_hctx_notify(void *data, unsigned long action,
unsigned int cpu)
static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
{
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;
cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
&hctx->cpuhp_dead);
}
/* hctx->ctxs will be freed in queue's release handler */
@ -1621,7 +1613,7 @@ static void blk_mq_exit_hctx(struct request_queue *q,
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
blk_mq_remove_cpuhp(hctx);
blk_free_flush_queue(hctx->fq);
sbitmap_free(&hctx->ctx_map);
}
@ -1668,9 +1660,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
hctx->queue_num = hctx_idx;
hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
blk_mq_hctx_notify, hctx);
blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
hctx->tags = set->tags[hctx_idx];
@ -1715,8 +1705,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
free_ctxs:
kfree(hctx->ctxs);
unregister_cpu_notifier:
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
blk_mq_remove_cpuhp(hctx);
return -1;
}
@ -2089,50 +2078,18 @@ 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
@ -2153,13 +2110,43 @@ 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_copy(&cpuhp_online_new, cpu_online_mask);
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)
@ -2378,10 +2365,12 @@ void blk_mq_enable_hotplug(void)
static int __init blk_mq_init(void)
{
blk_mq_cpu_init();
hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
blk_mq_hctx_notify_dead);
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);

7
block/blk-mq.h
View File

@ -32,13 +32,6 @@ void blk_mq_wake_waiters(struct request_queue *q);
/*
* CPU hotplug helpers
*/
struct blk_mq_cpu_notifier;
void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
int (*fn)(void *, unsigned long, 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);
void blk_mq_cpu_init(void);
void blk_mq_enable_hotplug(void);
void blk_mq_disable_hotplug(void);

8
include/linux/blk-mq.h
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@ -7,12 +7,6 @@
struct blk_mq_tags;
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);
};
struct blk_mq_hw_ctx {
struct {
spinlock_t lock;
@ -53,7 +47,7 @@ struct blk_mq_hw_ctx {
struct delayed_work delay_work;
struct blk_mq_cpu_notifier cpu_notifier;
struct hlist_node cpuhp_dead;
struct kobject kobj;
unsigned long poll_considered;