On Fri, 4 May 2018 10:32:06 -0700 "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> > > But preemptible RCU *does not* use context-switch as a quiescent state. > > > > It doesn't? > > It does, but only sort of. Ah, my confusion. I was thinking of rcu_read_lock_sched() as "preemptible RCU", not the "we can preempt in rcu_read_lock() context". -- Steve > > A context switch really is always an RCU-preempt quiescent state from > the perspective of the CPU. However, from the perspective of the task, > context switch is a quiescent state only if the task is not in an > RCU-preempt read-side critical section at the time.