blk-mq/cpu-notif: Convert to new hotplug state machine

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: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/Makefile b/block/Makefile
index 9eda232..ec97897 100644 (file)
--- a/block/Makefile
+++ b/block/Makefile
@@ -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/
 

diff --git a/block/blk-mq-cpu.c b/block/blk-mq-cpu.c
deleted file mode 100644 (file)
index bb3ed48..0000000
--- 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(&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);
-}

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e0a69da..e46e7ca 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1593,11 +1593,13 @@ fail:
  * 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);
@@ -1608,30 +1610,20 @@ 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 */
@@ -1651,7 +1643,7 @@ 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);
 }
@@ -1698,9 +1690,7 @@ 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];
 
@@ -1745,8 +1735,7 @@ 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;
 }
 
@@ -2399,7 +2388,8 @@ 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);
 

diff --git a/block/blk-mq.h b/block/blk-mq.h
index 9b15d2e..8fd3cc4 100644 (file)
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -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);
 

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index fbcfdf3..b3d1a7f 100644 (file)
--- 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;