Folllowing up on LSF/MM RCU/idle discussion

From: Paul E. McKenney
Date: Mon May 09 2022 - 11:56:41 EST


Hello, Jiri!

It was good chatting with you last week, and I hope that travels went
well!

Just wanted to follow up on the non-noinstr code between the call
to rcu_idle_enter() and rcu_idle_exit(). Although the most correct
approach is to never have non-noinstr code in arch_cpu_idle(), for all I
know there might well be architectures for which this is not feasible.
If so, one workaround would be to supply a flag set by each arch (or
subarch) that says that rcu_idle_enter() and rcu_idle_exit() are invoked
within arch_cpu_idle().

CCing Peter, who just might have an opinion on this. ;-)

Thanx, Paul