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

[Paul E. McKenney]

On Wed, Nov 11, 2026 at 02:40:36PM -0500, Mathieu Desnoyers wrote:
> 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! ;-)

I resemble that remark!  ;-)

							Thanx, Paul