On Sun, Oct 15, 2023 at 6:28 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > rcu is not used correctly here, because synchronize_rcu() is called > before replacing old value, for example: > > remove_and_add_spares // other path > synchronize_rcu > // called before replacing old value > set_bit(RemoveSynchronized) > rcu_read_lock() > rdev = conf->mirros[].rdev > pers->hot_remove_disk > conf->mirros[].rdev = NULL; > if (!test_bit(RemoveSynchronized)) > synchronize_rcu > /* > * won't be called, and won't wait > * for concurrent readers to be done. > /* > // access rdev after remove_and_add_spares() > rcu_read_unlock() I am having a hard time following the description here. Please be more specific about what issue we are fixing here. Thanks, Song > > Hence remove this flag and prepare to remove rcu protection to access > rdev from 'conf'. > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> > --- [...]
