linux-kernel - Re: [PATCH V5 09/11] riscv: Support HAVE_SOFTIRQ_ON_OWN

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Message-ID: <CAJF2gTRtRzeDqr3=AUkGadPMmMA6kwU86+zSNn8+0qXSk8zmVQ@mail.gmail.com>
Date:   Tue, 20 Sep 2022 08:11:55 +0800
From:   Guo Ren <guoren@...nel.org>
To:     arnd@...db.de, guoren@...nel.org, palmer@...osinc.com,
        tglx@...utronix.de, peterz@...radead.org, luto@...nel.org,
        conor.dooley@...rochip.com, heiko@...ech.de, jszhang@...nel.org,
        lazyparser@...il.com, falcon@...ylab.org, chenhuacai@...nel.org,
        apatel@...tanamicro.com, atishp@...shpatra.org, palmer@...belt.com,
        paul.walmsley@...ive.com, mark.rutland@....com,
        zouyipeng@...wei.com, bigeasy@...utronix.de,
        David.Laight@...lab.com
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH V5 09/11] riscv: Support HAVE_SOFTIRQ_ON_OWN_STACK

On Sun, Sep 18, 2022 at 11:53 PM <guoren@...nel.org> wrote:
>
> From: Guo Ren <guoren@...ux.alibaba.com>
>
> Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
> irq and softirq use the same independent irq_stack of percpu by time
> division multiplexing.
>
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@...nel.org>
> Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  arch/riscv/Kconfig      |  7 ++++---
>  arch/riscv/kernel/irq.c | 16 ++++++++++++++++
>  2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 75db47a983f2..dfe600f3526c 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -434,12 +434,13 @@ config FPU
>           If you don't know what to do here, say Y.
>
>  config IRQ_STACKS
> -       bool "Independent irq stacks" if EXPERT
> +       bool "Independent irq & softirq stacks" if EXPERT
>         default y
>         select HAVE_IRQ_EXIT_ON_IRQ_STACK
> +       select HAVE_SOFTIRQ_ON_OWN_STACK
>         help
> -         Add independent irq stacks for percpu to prevent kernel stack overflows.
> -         We may save some memory footprint by disabling IRQ_STACKS.
> +         Add independent irq & softirq stacks for percpu to prevent kernel stack
> +         overflows. We may save some memory footprint by disabling IRQ_STACKS.
>
>  endmenu # "Platform type"
>
> diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
> index 5ad4952203c5..6dc9ccd01470 100644
> --- a/arch/riscv/kernel/irq.c
> +++ b/arch/riscv/kernel/irq.c
> @@ -11,6 +11,7 @@
>  #include <linux/seq_file.h>
>  #include <asm/smp.h>
>  #include <asm/vmap_stack.h>
> +#include <asm/softirq_stack.h>
>
>  #ifdef CONFIG_IRQ_STACKS
>  static DEFINE_PER_CPU(ulong *, irq_stack_ptr);
> @@ -38,6 +39,21 @@ static void init_irq_stacks(void)
>                 per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);
>  }
>  #endif /* CONFIG_VMAP_STACK */
> +
> +#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
Sorry, it should be. If you compiled an error, please modify it manually,
+#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK

> +static void do_riscv_softirq(struct pt_regs *regs)
> +{
> +       __do_softirq();
> +}
> +
> +void do_softirq_own_stack(void)
> +{
> +       ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id());
> +
> +       call_on_stack(NULL, sp, do_riscv_softirq, 0);
> +}
> +#endif /* CONFIG_SOFTIRQ_ON_OWN_STACK */
> +
>  #else
>  static void init_irq_stacks(void) {}
>  #endif /* CONFIG_IRQ_STACKS */
> --
> 2.36.1
>


-- 
Best Regards
 Guo Ren