Re: [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking

On Wed, Sep 29, 2021 at 11:37:01AM -0700, Paul E. McKenney wrote:

quoted

+void context_tracking_idle(void)
+{
+	atomic_add_return(CT_SEQ, &raw_cpu_ptr(&context_tracking)->seq);

This is presumably a momentary idle.

quoted

 notrace void rcu_momentary_dyntick_idle(void)
 {
-	int seq;
-
 	raw_cpu_write(rcu_data.rcu_need_heavy_qs, false);
-	seq = rcu_dynticks_inc(2);
-	/* It is illegal to call this from idle state. */
-	WARN_ON_ONCE(!(seq & 0x1));
+	context_tracking_idle();
 	rcu_preempt_deferred_qs(current);
 }

It's whatever that is. It increments the actual sequence count without
modifying the state.