Messages in this thread | | | Date | Wed, 23 Nov 2022 09:54:37 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v2 rcu 05/16] rcu: Refactor code a bit in rcu_nocb_do_flush_bypass() |
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On Wed, Nov 23, 2022 at 04:59:29PM +0100, Frederic Weisbecker wrote: > On Mon, Nov 21, 2022 at 05:04:10PM -0800, Paul E. McKenney wrote: > > From: "Joel Fernandes (Google)" <joel@joelfernandes.org> > > > > This consolidates the code a bit and makes it cleaner. Functionally it > > is the same. > > > > Reported-by: Paul E. McKenney <paulmck@kernel.org> > > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > --- > > kernel/rcu/tree_nocb.h | 17 +++++++++-------- > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h > > index d6e4c076b0515..213daf81c057f 100644 > > --- a/kernel/rcu/tree_nocb.h > > +++ b/kernel/rcu/tree_nocb.h > > @@ -327,10 +327,11 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype, > > * > > * Note that this function always returns true if rhp is NULL. > > */ > > -static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > > +static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp_in, > > unsigned long j, bool lazy) > > { > > struct rcu_cblist rcl; > > + struct rcu_head *rhp = rhp_in; > > Why that intermediate rhp_in?
To avoid modifying the formal parameter, should the original value prove useful, for example, for tracing or debugging.
> > WARN_ON_ONCE(!rcu_rdp_is_offloaded(rdp)); > > rcu_lockdep_assert_cblist_protected(rdp); > > @@ -345,16 +346,16 @@ static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > > > > /* > > * If the new CB requested was a lazy one, queue it onto the main > > - * ->cblist so we can take advantage of a sooner grade period. > > + * ->cblist so that we can take advantage of the grace-period that will > > + * happen regardless. But queue it onto the bypass list first so that > > + * the lazy CB is ordered with the existing CBs in the bypass list. > > */ > > if (lazy && rhp) { > > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, NULL); > > - rcu_cblist_enqueue(&rcl, rhp); > > - WRITE_ONCE(rdp->lazy_len, 0); > > - } else { > > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > > - WRITE_ONCE(rdp->lazy_len, 0); > > + rcu_cblist_enqueue(&rdp->nocb_bypass, rhp); > > + rhp = NULL; > > } > > + rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > > + WRITE_ONCE(rdp->lazy_len, 0); > > Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Thank you! I will apply this on my next rebase.
Thanx, Paul
> Thanks. > > > > > rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl); > > WRITE_ONCE(rdp->nocb_bypass_first, j); > > -- > > 2.31.1.189.g2e36527f23 > >
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