On Tue, Dec 19, 2023 at 9:28 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote: > > 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@xxxxxxxxxx> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > block/blk-cgroup.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h > index fd482439afbc..b927a4a0ad03 100644 > --- a/block/blk-cgroup.h > +++ b/block/blk-cgroup.h > @@ -252,7 +252,8 @@ static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, > if (blkcg == &blkcg_root) > return q->root_blkg; > > - blkg = rcu_dereference(blkcg->blkg_hint); > + blkg = rcu_dereference_check(blkcg->blkg_hint, > + lockdep_is_held(&q->queue_lock)); > if (blkg && blkg->q == q) > return blkg; Hello, Ping... Thanks,
