Re: [PATCH v2 0/7] srcu: NMI-safe atomic SRCU readers, and their irqsave forms

[Mathieu Desnoyers]

On 2026-11-11 14:37, David Woodhouse wrote:
> On Wed, 2026-11-11 at 14:33 -0500, Mathieu Desnoyers wrote:
> > On 2026-11-11 14:02, David Woodhouse wrote:
> > > The latter claim is only true in __srcu_read_lock_fast()/_fast_updown()
> > > isn't it? Not in the atomic-SRCU. Unless we do something like this on
> > > top?
> >
> > It is true for the atomic readers as well.  Without
> > CONFIG_NEED_SRCU_NMI_SAFE, include/linux/srcu.h defines
> > __srcu_read_lock_nmisafe() as an inline that calls __srcu_read_lock(),
> > and the same for unlock.  So x86 keeps this_cpu_inc() and smp_mb().
> > Your diff selects the same functions by hand.
> >
> > Only the architectures that select NEED_SRCU_NMI_SAFE get the atomic
> > increments.
>
> You are lost in a twisty maze of helper functions, all alike...

I guess I had the best mentor in that regard! ;-)

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com