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From:   Guo Ren <guoren@kernel.org>
Date:   Sun, 24 Oct 2021 09:53:20 +0800
Message-ID: <CAJF2gTTn+vg-zT2HRMGxBU0iOhr-mVHNZb4e9saD-Tw7Mt3LYQ@mail.gmail.com>
Subject: Re: [PATCH 05/15] irq: add generic_handle_arch_irq()
To:     Mark Rutland <mark.rutland@arm.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Vincent Chen <deanbo422@gmail.com>,
        Greentime Hu <green.hu@gmail.com>,
        Jonas Bonn <jonas@southpole.se>, kernelfans@gmail.com,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Russell King <linux@armlinux.org.uk>,
        Marc Zyngier <maz@kernel.org>, Nick Hu <nickhu@andestech.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul McKenney <paulmck@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Stafford Horne <shorne@gmail.com>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        vgupta@kernel.org, Will Deacon <will@kernel.org>
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On Fri, Oct 22, 2021 at 4:52 PM Mark Rutland <mark.rutland@arm.com> wrote:
>
> On Fri, Oct 22, 2021 at 10:33:53AM +0800, Guo Ren wrote:
> > On Fri, Oct 22, 2021 at 2:03 AM Mark Rutland <mark.rutland@arm.com> wrote:
> > >
> > > Several architectures select GENERIC_IRQ_MULTI_HANDLER and branch to
> > > handle_arch_irq() without performing any entry accounting.
> > >
> > > Add a generic wrapper to handle the commoon irqentry work when invoking
>
> Ah, I'd typo'd 'common' there; I'll go fix that...
>
> > > handle_arch_irq(). Where an architecture needs to perform some entry
> > > accounting itself, it will need to invoke handle_arch_irq() itself.
> > >
> > > In subsequent patches it will become the responsibilty of the entry code
> > > to set the irq regs when entering an IRQ (rather than deferring this to
> > > an irqchip handler), so generic_handle_arch_irq() is made to set the irq
> > > regs now. This can be redundant in some cases, but is never harmful as
> > > saving/restoring the old regs nests safely.
> > Shall we remove old_regs save/restore in handle_domain_irq? It's duplicated.
>
> We do, in patch 15 when handle_domain_irq() is removed entirely. :)
I miss that patch. Yes, in generic_handle_domain_nmi.

>
> Removing it immediately in this patch would require more ifdeffery and/or
> another copy of handle_domain_irq(), and since the duplication doesn't cause a
> functional problem, I think it's better to live with the temporary duplication
> for the next few patches than to try to optimize the intermediate steps at the
> cost of legibility.
Thx for explaining.

Reviewed-by: Guo Ren <guoren@kernel.org>

>
> Thanks,
> Mark.
>
> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > > Cc: Marc Zyngier <maz@kernel.org>
> > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > ---
> > >  kernel/irq/handle.c | 18 ++++++++++++++++++
> > >  1 file changed, 18 insertions(+)
> > >
> > > diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
> > > index 221d80c31e94..27182003b879 100644
> > > --- a/kernel/irq/handle.c
> > > +++ b/kernel/irq/handle.c
> > > @@ -14,6 +14,8 @@
> > >  #include <linux/interrupt.h>
> > >  #include <linux/kernel_stat.h>
> > >
> > > +#include <asm/irq_regs.h>
> > > +
> > >  #include <trace/events/irq.h>
> > >
> > >  #include "internals.h"
> > > @@ -226,4 +228,20 @@ int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
> > >         handle_arch_irq = handle_irq;
> > >         return 0;
> > >  }
> > > +
> > > +/**
> > > + * generic_handle_arch_irq - root irq handler for architectures which do no
> > > + *                           entry accounting themselves
> > > + * @regs:      Register file coming from the low-level handling code
> > > + */
> > > +asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
> > > +{
> > > +       struct pt_regs *old_regs;
> > > +
> > > +       irq_enter();
> > > +       old_regs = set_irq_regs(regs);
> > > +       handle_arch_irq(regs);
> > > +       set_irq_regs(old_regs);
> > > +       irq_exit();
> > > +}
> > >  #endif
> > > --
> > > 2.11.0
> > >
> >
> >
> > --
> > Best Regards
> >  Guo Ren
> >
> > ML: https://lore.kernel.org/linux-csky/


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/