Re: [PATCH v2 0/6] sched: dynamic: Simplify PREEMPT_DYNAMIC

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 8/4/26 12:47 AM, Mark Rutland wrote:
> All architectures which currently suppoort PREEMPT_DYNAMIC select
> ARCH_HAS_PREEMPT_LAZY.  On architectures which select
> ARCH_HAS_PREEMPT_LAZY, it has not been possible to select the NONE and
> VOLUNTARY preemption models since v7.0 due to commit:
> 
>    7dadeaa6e851 ("sched: Further restrict the preemption modes")
> 
> Hence in practice PREEMPT_DYNAMIC no longer supports the NONE or
> VOLUNTARY preemption models.
> 
> This series makes the de-facto situation official by making
> PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY, and removing redundant
> code.
> 
> Since v1, I've had to rebase atop v7.2-rc4 to avoid a conflict with
> commit:
> 
>    a2c02aa0c6ca ("powerpc: Remove dead non-preemption code")
> 
> Given this is now late in the cycle, and given the tip:sched/core branch
> is based on v7.2-rc1, I suspect tip folk might not want to queue this
> now. Please let me know what you'd prefer; I'm happy to rebase and
> resend after v7.3-rc1.
> 
> Since v1:
> * Rebase to v7.2-rc4
> * Apply Revied-by tags.
> * Fix typos in commit messages.
> * Add patch to cleanup accessors (per Shrikanth's comment)
> 
> Mark.
> 

I have tested with and without PREEMPT_DYNAMIC for lazy/full.
I haven't observed anything odd.

For the series,
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>

> Mark Rutland (6):
>    sched: dynamic: Make PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY
>    sched: dynamic: Simplify {cond,might}_resched()
>    sched: dynamic: Simplify preempt_schedule{,_notrace}()
>    sched: dynamic: Simplify irqentry_exit_cond_resched()
>    sched: dynamic: Remove HAVE_PREEMPT_DYNAMIC_{CALL,KEY}
>    sched: dynamic: Simplify preempt model accessors
> 
>   arch/Kconfig                     |  38 -------
>   arch/arm64/Kconfig               |   1 -
>   arch/arm64/include/asm/preempt.h |  10 --
>   arch/loongarch/Kconfig           |   1 -
>   arch/powerpc/Kconfig             |   1 -
>   arch/riscv/Kconfig               |   1 -
>   arch/s390/Kconfig                |   1 -
>   arch/s390/include/asm/preempt.h  |  11 --
>   arch/x86/Kconfig                 |   1 -
>   arch/x86/include/asm/preempt.h   |  28 -----
>   include/asm-generic/preempt.h    |  10 --
>   include/linux/irq-entry-common.h |  17 +--
>   include/linux/kernel.h           |  20 ----
>   include/linux/preempt.h          |  20 ++--
>   include/linux/sched.h            |  31 +-----
>   kernel/Kconfig.preempt           |   9 +-
>   kernel/entry/common.c            |  17 +--
>   kernel/sched/core.c              | 180 +------------------------------
>   18 files changed, 23 insertions(+), 374 deletions(-)
>