Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Uladzislau Rezki]

On Tue, Jul 14, 2020 at 09:02:53PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-07-14 11:27:32 [-0700], Paul E. McKenney wrote:
> > I believe that Ulad and Joel are working on an update.
>
> I expressed multiple times that I am unhappy with the raw_spinlock_t
> which both want to keep. It is important to be future proof but at the
> same time I am not sure if they know how many in-hardirq kmalloc() or
> kfree() invocation we have as of today in PREEMPT_RT.
>
It is not about counting how many times kfree_rcu() gets called from
the hard IRQ context for RT kernel. In fact it is about breaking of
such possibility if a conversion to spinlock_t is done. Is not it?

As a result the revert would change a behavior of the API function,
that is used to accept such usage. That is a motivation.

--
Vlad Rezki