linux-kernel - Re: [PATCH 13/15] irq: riscv: perform irqentry in entry code

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Date:   Wed, 27 Oct 2021 14:22:25 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     mark.rutland@....com
CC:     linux-kernel@...r.kernel.org, aou@...s.berkeley.edu,
        catalin.marinas@....com, deanbo422@...il.com, green.hu@...il.com,
        guoren@...nel.org, jonas@...thpole.se, kernelfans@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux@...linux.org.uk,
        mark.rutland@....com, Marc Zyngier <maz@...nel.org>,
        nickhu@...estech.com, paulmck@...nel.org,
        Paul Walmsley <paul.walmsley@...ive.com>, peterz@...radead.org,
        shorne@...il.com, stefan.kristiansson@...nalahti.fi,
        tglx@...utronix.de, Linus Torvalds <torvalds@...ux-foundation.org>,
        tsbogend@...ha.franken.de, vgupta@...nel.org, will@...nel.org
Subject:     Re: [PATCH 13/15] irq: riscv: perform irqentry in entry code

On Thu, 21 Oct 2021 11:02:34 PDT (-0700), mark.rutland@....com wrote:
> In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/riscv
> perform all the irqentry accounting in its entry code. As arch/riscv
> uses GENERIC_IRQ_MULTI_HANDLER, we can use generic_handle_arch_irq() to
> do so.
>
> Since generic_handle_arch_irq() handles the irq entry and setting the
> irq regs, and happens before the irqchip code calls handle_IPI(), we can
> remove the redundant irq entry and irq regs manipulation from
> handle_IPI().
>
> There should be no functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Albert Ou <aou@...s.berkeley.edu>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Palmer Dabbelt <palmer@...belt.com>
> Cc: Paul Walmsley <paul.walmsley@...ive.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/riscv/Kconfig        | 1 -
>  arch/riscv/kernel/entry.S | 3 +--
>  arch/riscv/kernel/smp.c   | 9 +--------
>  3 files changed, 2 insertions(+), 11 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 740653063a56..301a54233c7e 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -63,7 +63,6 @@ config RISCV
>  	select GENERIC_SMP_IDLE_THREAD
>  	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
>  	select HANDLE_DOMAIN_IRQ
> -	select HANDLE_DOMAIN_IRQ_IRQENTRY
>  	select HAVE_ARCH_AUDITSYSCALL
>  	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
>  	select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 98f502654edd..64236f7efde5 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -130,8 +130,7 @@ skip_context_tracking:
>
>  	/* Handle interrupts */
>  	move a0, sp /* pt_regs */
> -	la a1, handle_arch_irq
> -	REG_L a1, (a1)
> +	la a1, generic_handle_arch_irq
>  	jr a1
>  1:
>  	/*
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index 921d9d7df400..2f6da845c9ae 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -140,12 +140,9 @@ void arch_irq_work_raise(void)
>
>  void handle_IPI(struct pt_regs *regs)
>  {
> -	struct pt_regs *old_regs = set_irq_regs(regs);
>  	unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
>  	unsigned long *stats = ipi_data[smp_processor_id()].stats;
>
> -	irq_enter();
> -
>  	riscv_clear_ipi();
>
>  	while (true) {
> @@ -156,7 +153,7 @@ void handle_IPI(struct pt_regs *regs)
>
>  		ops = xchg(pending_ipis, 0);
>  		if (ops == 0)
> -			goto done;
> +			return;
>
>  		if (ops & (1 << IPI_RESCHEDULE)) {
>  			stats[IPI_RESCHEDULE]++;
> @@ -189,10 +186,6 @@ void handle_IPI(struct pt_regs *regs)
>  		/* Order data access and bit testing. */
>  		mb();
>  	}
> -
> -done:
> -	irq_exit();
> -	set_irq_regs(old_regs);
>  }
>
>  static const char * const ipi_names[] = {

Acked-by: Palmer Dabbelt <palmerdabbelt@...gle.com>

I'm assuming you want to keep these togther.