[PATCH AUTOSEL 5.10 7/9] blk-iocost: fix lockdep warning on blkcg->lock

[Sasha Levin]

From: Ming Lei <ming.lei@xxxxxxxxxx>

[ Upstream commit 11431e26c9c43fa26f6b33ee1a90989f57b86024 ]

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@xxxxxxxxxx>
Reported-by: Bruno Goncalves <bgoncalv@xxxxxxxxxx>
Link: https://lore.kernel.org/linux-block/CA+QYu4rzz6079ighEanS3Qq_Dmnczcf45ZoJoHKVLVATTo1e4Q@xxxxxxxxxxxxxx/T/#u
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210803070608.1766400-1-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 block/blk-iocost.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index b7d8a954d99c..e95b93f72bd5 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3039,19 +3039,19 @@ 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;
 	}
-- 
2.30.2