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authorBart Van Assche <bart.vanassche@wdc.com>2018-02-28 10:15:33 -0800
committerJens Axboe <axboe@kernel.dk>2018-02-28 12:23:35 -0700
commita063057d7c731cffa7d10740e8ebc2970df8dbb3 (patch)
tree40895bc044e82ff993d698128c5b24f6d0c82c0a /block/blk-sysfs.c
parent498f6650aec864e331cae7575fec5f07781d0bf3 (diff)
downloadlinux-0-day-a063057d7c731cffa7d10740e8ebc2970df8dbb3.tar.gz
block: Fix a race between request queue removal and the block cgroup controller
Avoid that the following race can occur: blk_cleanup_queue() blkcg_print_blkgs() spin_lock_irq(lock) (1) spin_lock_irq(blkg->q->queue_lock) (2,5) q->queue_lock = &q->__queue_lock (3) spin_unlock_irq(lock) (4) spin_unlock_irq(blkg->q->queue_lock) (6) (1) take driver lock; (2) busy loop for driver lock; (3) override driver lock with internal lock; (4) unlock driver lock; (5) can take driver lock now; (6) but unlock internal lock. This change is safe because only the SCSI core and the NVME core keep a reference on a request queue after having called blk_cleanup_queue(). Neither driver accesses any of the removed data structures between its blk_cleanup_queue() and blk_put_queue() calls. Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r--block/blk-sysfs.c7
1 files changed, 0 insertions, 7 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index cbea895..fd71a00 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -798,13 +798,6 @@ static void __blk_release_queue(struct work_struct *work)
if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
blk_stat_remove_callback(q, q->poll_cb);
blk_stat_free_callback(q->poll_cb);
- bdi_put(q->backing_dev_info);
- blkcg_exit_queue(q);
-
- if (q->elevator) {
- ioc_clear_queue(q);
- elevator_exit(q, q->elevator);
- }
blk_free_queue_stats(q->stats);