Re: [RFC PATCH 49/49] ARM: mm: Move CPUHP_AP_ARM_CACHE_B15_RAC_DYING post stop_machine()

[Florian Fainelli <florian.fainelli@broadcom.com>]

On 10/19/26 06:08, Frederic Weisbecker wrote:
> Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes
> all the teardown callbacks while stopping all CPUs in the system. This
> doesn't mix-up well with running RT or isolated tasks.
> 
> In order to transition smoothly from global stop_machine to finer
> grained synchronization between teardown callbacks and the other CPUs,
> a new stop machine post function has been introduced to be executed
> after the main one with IRQs still disabled while other CPUs can exit
> stop_machine().
> 
> It *looks ok* to disable the cache readahead globally while the other
> CPUs are running.

Yes I think it is safe given that b15_rac_dying_cpu() will run on the 
dying CPU and any CPU that is left will basically re-enable the RAC 
afterwards if necessary in b15_rac_dead_cpu().

The hardware to test this is quite ancient, but if you give me a test 
case to exercise, I can give it a spin.

Thank you Frederic!
-- 
Florian