[PATCH 0/4] 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

Akinobu Mita (4):
  blk-mq: fix sysfs registration/unregistration race
  blk-mq: fix q->mq_map access race
  blk-mq: establish new mapping before cpu starts handling requests
  blk-mq: fix mq_usage_counter race when switching to percpu mode

 block/blk-mq-cpumap.c  |  9 ++++----
 block/blk-mq-sysfs.c   | 21 +++++++++++++++++--
 block/blk-mq.c         | 56 +++++++++++++++++++++++++++++++++-----------------
 block/blk-mq.h         |  3 ++-
 include/linux/blk-mq.h |  1 +
 include/linux/blkdev.h |  6 ++++++
 6 files changed, 70 insertions(+), 26 deletions(-)

-- 
1.9.1

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