blk-cgroup: fix rcu lockdep warning in blkg_lookup()
authorMing Lei <ming.lei@redhat.com>
Tue, 19 Dec 2023 01:28:33 +0000 (09:28 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 25 Jan 2024 23:35:30 +0000 (15:35 -0800)
commita33c741ca6997da7e3d3e2152c0422e4d8820f08
treed2f12b0d743eb109097fa0843d1febaf7ea44b7c
parent63c3c44ff4c535157e7574452c9f37d93dafdd20
blk-cgroup: fix rcu lockdep warning in blkg_lookup()

[ Upstream commit 393cd8ffd832f23eec3a105553eff622e8198918 ]

blkg_lookup() is called with either queue_lock or rcu read lock, so
use rcu_dereference_check(lockdep_is_held(&q->queue_lock)) for
retrieving 'blkg', which way models the check exactly for covering
queue lock or rcu read lock.

Fix lockdep warning of "block/blk-cgroup.h:254 suspicious rcu_dereference_check() usage!"
from blkg_lookup().

Tested-by: Changhui Zhong <czhong@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Fixes: 83462a6c971c ("blkcg: Drop unnecessary RCU read [un]locks from blkg_conf_prep/finish()")
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231219012833.2129540-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
block/blk-cgroup.h