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blk-iocost: fix lockdep warning on blkcg->lock

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blkcg->lock depends on q->queue_lock which may depend on another driver
lock required in irq context, one example is dm-thin:

	Chain exists of:
	  &pool->lock#3 --> &q->queue_lock --> &blkcg->lock

	 Possible interrupt unsafe locking scenario:

	       CPU0                    CPU1
	       ----                    ----
	  lock(&blkcg->lock);
	                               local_irq_disable();
	                               lock(&pool->lock#3);
	                               lock(&q->queue_lock);
	  <Interrupt>
	    lock(&pool->lock#3);

Fix the issue by using spin_lock_irq(&blkcg->lock) in ioc_weight_write().

Cc: Tejun Heo <tj@kernel.org>
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Link: https://lore.kernel.org/linux-block/CA+QYu4rzz6079ighEanS3Qq_Dmnczcf45ZoJoHKVLVATTo1e4Q@mail.gmail.com/T/#u
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210803070608.1766400-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2021-08-03 15:06:08 +08:00 committed by Jens Axboe
parent fb7b9b0231
commit 11431e26c9
1 changed files with 4 additions and 4 deletions
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8
block/blk-iocost.c
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@ -3061,19 +3061,19 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
return -EINVAL;
spin_lock(&blkcg->lock);
spin_lock_irq(&blkcg->lock);
iocc->dfl_weight = v * WEIGHT_ONE;
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct ioc_gq *iocg = blkg_to_iocg(blkg);
if (iocg) {
spin_lock_irq(&iocg->ioc->lock);
spin_lock(&iocg->ioc->lock);
ioc_now(iocg->ioc, &now);
weight_updated(iocg, &now);
spin_unlock_irq(&iocg->ioc->lock);
spin_unlock(&iocg->ioc->lock);
}
}
spin_unlock(&blkcg->lock);
spin_unlock_irq(&blkcg->lock);
return nbytes;
}