On Thu, Jul 30, 2020 at 09:35:20AM -0700, Paul E. McKenney wrote:
> On Wed, Jul 29, 2020 at 11:25:19PM -0400, Joel Fernandes wrote:
> > On Wed, Jul 29, 2020 at 11:02 PM Joel Fernandes (Google)
> > <joel@xxxxxxxxxxxxxxxxx> wrote:
> > >
> > > At least since v4.19, the FQS loop no longer reports quiescent states
> >
> > I meant here, "FQS loop no longer reports quiescent states for offline CPUs."
> >
> > Sorry,
>
> You did have me going there for a bit. ;-)
>
> No period (".") at the end though, unless you fix up the following
> to start a new sentence.
Ok.
> > > unless it is a dire situation where an offlined CPU failed to report
> > > a quiescent state. Let us clarify the comment in rcu_gp_init() inorder
> > > to keep the comment current.
>
> How about the following for this last sentence?
>
> "This commit therefore fixes the comment in rcu_gp_init() to match
> the current code."
As per:
https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html
It says:
Describe your changes in imperative mood, e.g. “make xyzzy do frotz” instead
of “[This patch] makes xyzzy do frotz” or “[I] changed xyzzy to do frotz”, as
if you are giving orders to the codebase to change its behaviour.
May be I should make it "Fix the comment in rcu_gp_init() to match the
current code"?
> > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> > > ---
> > > kernel/rcu/tree.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > index 1e51962b565b..929568ff5989 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -1701,8 +1701,8 @@ static bool rcu_gp_init(void)
> > >
> > > /*
> > > * Apply per-leaf buffered online and offline operations to the
> > > - * rcu_node tree. Note that this new grace period need not wait
> > > - * for subsequent online CPUs, and that quiescent-state forcing
> > > + * rcu_node tree. Note that this new grace period need not wait for
> > > + * subsequent online CPUs, and that RCU hooks in CPU offlining path
> > > * will handle subsequent offline CPUs.
>
> How about something like this?
>
> ... Note that this new grace period ned not wait for subsequent
> online CPUs, and that RCU hooks in the CPU offlining path, when
> combined with checks in this function, will handle CPUs that
> are currently going offline and that go offline later.
Sounds good to me. I think s/and that go/or that go/ though.
I will make these changes and send v3, let me know though if you object.
thanks,
- Joel
> Thanx, Paul
>
> > > */
> > > rcu_state.gp_state = RCU_GP_ONOFF;
> > > --
> > > 2.28.0.rc0.142.g3c755180ce-goog
> > >
