Re: [PATCH v4 00/11] s390: More this_cpu_*() changes

[Alexander Gordeev]

On Mon, Sep 21, 2026 at 05:57:54PM +0200, Heiko Carstens wrote:
...
> Most of this is only about cleaning up the percpu code after preemptible
> this_cpu_*() operations have been implemented. The first ten patches are
> all more or less trivial cleanup patches trying to make the code shorter
> and more readable.
> 
> The only non-trivial patch is the last one, which converts s390's
> this_cpu_*() operations to use a similar scheme like Mark Rutland
> provided it for arm64 [1]. This allows to simplify the irq entry and exit
> path, however at the cost of slightly worse code for this_cpu_*()
> operations.
> 
> The simplified irq entry and exit code seems to be worth it. Usable

To me it absolutely worth it!

> performance numbers are not available yet, however I don't expect big
> difference to before.
> 
> [1] https://lore.kernel.org/all/20260904161758.376504-1-mark.rutland@xxxxxxx/
> 
> Thanks,
> Heiko
> 
> Heiko Carstens (11):
>   s390/percpu: Fix comment typo
>   s390/percpu: Add sanity check to GEN_MVIY macro
>   s390/lowcore: Remove _AC() from LOWCORE_ALT_ADDRESS
>   s390/percpu: Let MVIY_PERCPU() calculate alternative displacement
>   s390/percpu/lowcore: Add and use LC_PERCPU lowcore offset defines
>   s390/percpu: Rename inline assembly symbolic names
>   s390/percpu: Use __PCPU_BEGIN() and __PCPU_END() for inline assemblies
>   s390/percpu: Use percpu code section for this_cpu_cmpxchg128()
>   s390/percpu: Use percpu code section for this_cpu_xchg()
>   s390/percpu: Use percpu code section for this_cpu_cmpxchg()
>   s390/percpu: Rework to simplify percpu_entry() and percpu_exit()
> 
>  arch/s390/include/asm/entry-percpu.h |  71 ++----
>  arch/s390/include/asm/lowcore.h      |   5 +-
>  arch/s390/include/asm/percpu.h       | 354 +++++++++++++++++----------
>  arch/s390/kernel/irq.c               |  10 +-
>  arch/s390/kernel/nmi.c               |   4 +-
>  arch/s390/kernel/traps.c             |   4 +-
>  6 files changed, 248 insertions(+), 200 deletions(-)

Acked-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>