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

From: Akinobu Mita
Date: Thu Jul 02 2015 - 10:30:28 EST


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@xxxxxxxxx>
Cc: Ming Lei <tom.leiming@xxxxxxxxx>
--
1.9.1

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