Re: [PATCH -next v5 07/22] arm64: entry: preempt_schedule_irq() only if PREEMPTION enabled

Mark Rutland
2025-02-10T12:17:44Z

On Fri, Dec 06, 2024 at 06:17:29PM +0800, Jinjie Ruan wrote:
> The generic entry check PREEMPTION for both PREEMPT_DYNAMIC
> enabled and PREEMPT_DYNAMIC disabled.
>
> Whether PREEMPT_DYNAMIC enabled or not, PREEMPTION should
> be enabled to allow reschedule before EL1 exception return, so
> move PREEMPTION check ahead in preparation for moving arm64 over
> to the generic entry code.

This is just moving the IS_ENABLED() check. It'd be clearer to say
something like "hoist the IS_ENABLED() check earlier", but equally we
could do that earleir in the series by folding this into the prior
patch.

Mark.

>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
> arch/arm64/kernel/entry-common.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
> index 80b47ca02db2..029f8bd72f8a 100644
> --- a/arch/arm64/kernel/entry-common.c
> +++ b/arch/arm64/kernel/entry-common.c
> @@ -109,9 +109,6 @@ void raw_irqentry_exit_cond_resched(void)
> #ifdef CONFIG_PREEMPT_DYNAMIC
> if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
> return;
> -#else
> - if (!IS_ENABLED(CONFIG_PREEMPTION))
> - return;
> #endif
>
> if (!preempt_count()) {
> @@ -142,7 +139,8 @@ static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs,
> return;
> }
>
> - raw_irqentry_exit_cond_resched();
> + if (IS_ENABLED(CONFIG_PREEMPTION))
> + raw_irqentry_exit_cond_resched();
>
> trace_hardirqs_on();
> } else {
> --
> 2.34.1
>