Re: [PATCH v1 09/11] rcu: Detect expedited grace period completion in rcu_pending()

On Tue, Jul 21, 2026 at 02:45:36PM +0200, Frederic Weisbecker wrote:
> Le Wed, Jun 24, 2026 at 06:23:51AM -0700, Puranjay Mohan a écrit :
> > rcu_pending() decides whether rcu_core() should run on the current CPU's
> > timer tick.  It does not account for expedited grace periods: after an
> > expedited GP completes, a non-offloaded CPU's callbacks remain in
> > RCU_WAIT_TAIL (not yet advanced to RCU_DONE_TAIL) and rcu_core() is
> > never invoked to advance them.
> > 
> > Detect that case via rcu_segcblist_nextgp() combined with a new
> > memory-ordering-free poll variant,
> > poll_state_synchronize_rcu_full_unordered().  This keeps rcu_pending()
> > cheap: it runs on every tick that has pending callbacks, so it must
> > not pay for the two memory barriers in
> > poll_state_synchronize_rcu_full().  The check is only a hint to run
> > rcu_core(); the ordered re-check and the actual callback advancement
> > happen there.
> > 
> > Signed-off-by: Puranjay Mohan <[email protected]>
> 
> Reviewed-by: Frederic Weisbecker <[email protected]>

Thank you!  I will apply this on my next rebase.

							Thanx, Paul