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SubjectRe: [PATCH 1/3] srcu: Remove superfluous ssp initialization on deferred work queue
On Thu, Apr 01, 2021 at 05:48:56PM -0700, Paul E. McKenney wrote:
> On Fri, Apr 02, 2021 at 01:47:02AM +0200, Frederic Weisbecker wrote:
> > When an ssp has already started a grace period and queued an early work
> > to flush after SRCU workqueues are created, we expect the ssp to be
> > properly initialized already. So we can skip this step at this stage.
> >
> > Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> > Cc: Boqun Feng <boqun.feng@gmail.com>
> > Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> > Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
> > Cc: Josh Triplett <josh@joshtriplett.org>
> > Cc: Joel Fernandes <joel@joelfernandes.org>
> > Cc: Uladzislau Rezki <urezki@gmail.com>
> > ---
> > kernel/rcu/srcutree.c | 1 -
> > 1 file changed, 1 deletion(-)
> >
> > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> > index 036ff5499ad5..7197156418e4 100644
> > --- a/kernel/rcu/srcutree.c
> > +++ b/kernel/rcu/srcutree.c
> > @@ -1396,7 +1396,6 @@ void __init srcu_init(void)
> > while (!list_empty(&srcu_boot_list)) {
> > ssp = list_first_entry(&srcu_boot_list, struct srcu_struct,
> > work.work.entry);
> > - check_init_srcu_struct(ssp);
>
> You lost me on this one. What happens if the only pre-initialization
> invocation on the statically allocated srcu_struct pointed to by ssp
> was call_srcu()? I am not seeing how the initialization has already
> happened in that case.
>
> What am I missing here?

Idiot here was looking at Tiny SRCU's call_srcu(), not that of Tree SRCU.
Never mind, I will queue this one as well.

Thanx, Paul

> > list_del_init(&ssp->work.work.entry);
> > queue_work(rcu_gp_wq, &ssp->work.work);
> > }
> > --
> > 2.25.1
> >

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