linux-kernel - Re: [PATCH 02/15] irq: mips: stop (ab)using handle_domain

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Date:   Sun, 24 Oct 2021 17:30:41 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Mark Rutland <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,
        maz@...nel.org, nickhu@...estech.com, palmer@...belt.com,
        paulmck@...nel.org, paul.walmsley@...ive.com, peterz@...radead.org,
        shorne@...il.com, stefan.kristiansson@...nalahti.fi,
        tglx@...utronix.de, torvalds@...ux-foundation.org,
        vgupta@...nel.org, will@...nel.org
Subject: Re: [PATCH 02/15] irq: mips: stop (ab)using handle_domain_irq()

On Thu, Oct 21, 2021 at 07:02:23PM +0100, Mark Rutland wrote:
> On MIPS, the only user of handle_domain_irq() is octeon_irq_ciu3_ip2(),
> which is called from the platform-specific plat_irq_dispatch() function
> invoked from the early assembly code.
> 
> No other irqchip relevant to arch/mips uses handle_domain_irq():
> 
> * No other plat_irq_dispatch() function transitively calls
>   handle_domain_irq().
> 
> * No other vectored IRQ dispatch function registered with
>   set_vi_handler() calls handle_domain_irq().
> 
> * No chained irqchip handlers call handle_domain_irq(), which makes
>   sense as this is meant to only be used by root irqchip handlers.
> 
> Currently octeon_irq_ciu3_ip2() passes NULL as the `regs` argument to
> handle_domain_irq(), and as handle_domain_irq() will pass this to
> set_irq_regs(), any invoked IRQ handlers will erroneously see a NULL
> pt_regs if they call get_pt_regs().
> 
> Fix this by calling generic_handle_domain_irq() directly, and performing
> the necessary irq_{enter,exit}() logic directly in
> octeon_irq_ciu3_ip2(). At the same time, deselect HANDLE_DOMAIN_IRQ,
> which subsequent patches will remove.
> 
> Other than the corrected behaviour of get_pt_regs(), there should be no
> functional change as a result of this patch.
> 
> Fixes: ce210d35bb93c2c5 ("MIPS: OCTEON: Add support for OCTEON III interrupt controller.")
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/mips/Kconfig                    | 1 -
>  arch/mips/cavium-octeon/octeon-irq.c | 5 ++++-
>  2 files changed, 4 insertions(+), 2 deletions(-)

Acked-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>

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