On Thu, Nov 08, 2018 at 05:02:57PM +0100, Sebastian Andrzej Siewior wrote: > On 2018-11-01 16:18:04 [-0700], Paul E. McKenney wrote: > > The need for this goes away as of the current merge window because > > RCU-bh has gone away. (Aside from still being able to do things > > like rcu_read_lock_bh() as a documentation device.) > > So in -RT rcu_read_lock_bh() does > { local_bh_disable() ; rcu_read_lock() } > > So you are saying that this is also the case in v4.20? No, rcu_read_lock_bh() and rcu_read_unlock_bh() are unchanged in v4.20. With the new RCU grace-period mechanism, local_bh_disable() blocks future grace periods on its own. Unless I am missing something (quite probable, actually), the v4.20 definitions of rcu_read_lock_bh() and rcu_read_unlock_bh() should work as-is for -rt. Thanx, Paul