* [patch V2 2/2] blk/mq: Convert to hotplug state machine
2016-09-20 15:21 [patch V2 0/2] block/mq: Convert to new hotplug state machine Thomas Gleixner
@ 2016-09-20 15:21 ` Thomas Gleixner
2016-09-20 15:21 ` [patch V2 1/2] blk/mq/cpu-notif: " Thomas Gleixner
2016-09-21 3:48 ` [patch V2 0/2] block/mq: Convert to new " Jens Axboe
2 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2016-09-20 15:21 UTC (permalink / raw)
To: LKML
Cc: linux-block, Jens Axboe, Christoph Hellwing, Sebastian Siewior,
Peter Zijlstra, rt
[-- Attachment #1: blkmq_Convert_to_hotplug_state_machine.patch --]
[-- Type: text/plain, Size: 4585 bytes --]
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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: Jens Axboe <axboe@kernel.dk>
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>
---
block/blk-mq.c | 87 ++++++++++++++++++++++++++++-----------------------------
1 file changed, 43 insertions(+), 44 deletions(-)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2090,50 +2090,18 @@ static void blk_mq_queue_reinit(struct r
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
@@ -2154,13 +2122,43 @@ static int blk_mq_queue_reinit_notify(st
}
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)
@@ -2382,8 +2380,9 @@ 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);
^ permalink raw reply [flat|nested] 6+ messages in thread* [patch V2 1/2] blk/mq/cpu-notif: Convert to hotplug state machine
2016-09-20 15:21 [patch V2 0/2] block/mq: Convert to new hotplug state machine Thomas Gleixner
2016-09-20 15:21 ` [patch V2 2/2] blk/mq: Convert to " Thomas Gleixner
@ 2016-09-20 15:21 ` Thomas Gleixner
2016-09-21 3:48 ` [patch V2 0/2] block/mq: Convert to new " Jens Axboe
2 siblings, 0 replies; 6+ messages in thread
From: Thomas Gleixner @ 2016-09-20 15:21 UTC (permalink / raw)
To: LKML
Cc: linux-block, Jens Axboe, Christoph Hellwing, Sebastian Siewior,
Peter Zijlstra, rt
[-- Attachment #1: blkmqcpu-notif_Convert_to_hotplug_state_machine.patch --]
[-- Type: text/plain, Size: 6566 bytes --]
Replace the block-mq notifier list management with the multi instance
facility in the cpu hotplug state machine.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
---
block/Makefile | 2 -
block/blk-mq-cpu.c | 67 -------------------------------------------------
block/blk-mq.c | 36 +++++++++-----------------
block/blk-mq.h | 7 -----
include/linux/blk-mq.h | 8 -----
5 files changed, 15 insertions(+), 105 deletions(-)
--- a/block/Makefile
+++ b/block/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.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/
--- a/block/blk-mq-cpu.c
+++ /dev/null
@@ -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(¬ifier->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(¬ifier->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);
-}
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1575,11 +1575,13 @@ static struct blk_mq_tags *blk_mq_init_r
* 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);
@@ -1590,30 +1592,20 @@ static int blk_mq_hctx_cpu_offline(struc
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 */
@@ -1633,7 +1625,7 @@ static void blk_mq_exit_hctx(struct requ
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);
}
@@ -1680,9 +1672,7 @@ static int blk_mq_init_hctx(struct reque
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];
@@ -1727,8 +1717,7 @@ static int blk_mq_init_hctx(struct reque
free_ctxs:
kfree(hctx->ctxs);
unregister_cpu_notifier:
- blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
-
+ blk_mq_remove_cpuhp(hctx);
return -1;
}
@@ -2390,7 +2379,8 @@ void blk_mq_enable_hotplug(void)
static int __init blk_mq_init(void)
{
- blk_mq_cpu_init();
+ 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);
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -32,13 +32,6 @@ void blk_mq_wake_waiters(struct request_
/*
* 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);
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -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;
^ permalink raw reply [flat|nested] 6+ messages in thread