[PATCH v2 0/6] blk-mq: fix race conditions on cpu hotplug handling

[Akinobu Mita <akinobu.mita@gmail.com>]

This patchset addresses several race conditions on cpu hotplug handling
for blk-mq.  All problems are reproducible by the following script.

while true; do
	echo 0 > /sys/devices/system/cpu/cpu1/online
	echo 1 > /sys/devices/system/cpu/cpu1/online
done &

while true; do
	modprobe -r null_blk
	modprobe null_blk queue_mode=2 irqmode=1
	sleep 0.1
done

* Changes from v1
- Release q->mq_map in blk_mq_release()
- Fix deadlock when reading cpu_list
- Fix race freeze and unfreeze

Akinobu Mita (6):
  blk-mq: fix sysfs registration/unregistration race
  blk-mq: Fix use after of free q->mq_map
  blk-mq: fix q->mq_usage_counter access race
  blk-mq: avoid inserting requests before establishing new mapping
  blk-mq: fix freeze queue race
  blk-mq: fix deadlock when reading cpu_list

 block/blk-core.c       |  2 ++
 block/blk-mq-cpumap.c  |  9 +++---
 block/blk-mq-sysfs.c   | 50 ++++++++++++++++++++++---------
 block/blk-mq.c         | 81 ++++++++++++++++++++++++++++++--------------------
 block/blk-mq.h         |  5 ++--
 include/linux/blkdev.h |  9 ++++++
 6 files changed, 102 insertions(+), 54 deletions(-)

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <tom.leiming@gmail.com>
-- 
1.9.1