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From:   Rob Herring <robh@kernel.org>
Date:   Mon, 24 May 2021 08:28:42 -0500
Message-ID: <CAL_JsqLWLLRmusfvAweahA=ZKxOChRWAVUKehShpvn60kScsrw@mail.gmail.com>
Subject: Re: [PATCH 30/39] PCI: Bulk conversion to generic_handle_domain_irq()
To:     Marc Zyngier <maz@kernel.org>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Ley Foon Tan <ley.foon.tan@intel.com>,
        Chris Zankel <chris@zankel.net>,
        Max Filippov <jcmvbkbc@gmail.com>,
        Vineet Gupta <vgupta@synopsys.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Robert Jarzmik <robert.jarzmik@free.fr>,
        Russell King <linux@armlinux.org.uk>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Clark <robdclark@gmail.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Lee Jones <lee.jones@linaro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Android Kernel Team <kernel-team@android.com>
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On Mon, May 24, 2021 at 3:38 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Thu, 20 May 2021 18:47:06 +0100,
> Rob Herring <robh@kernel.org> wrote:
> >
> > On Thu, May 20, 2021 at 11:57 AM Marc Zyngier <maz@kernel.org> wrote:
> > >
> > > Wherever possible, replace constructs that match either
> > > generic_handle_irq(irq_find_mapping()) or
> > > generic_handle_irq(irq_linear_revmap()) to a single call to
> > > generic_handle_domain_irq().
> > >
> > > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > > ---
> > >  drivers/pci/controller/dwc/pci-dra7xx.c        | 14 +++++---------
> > >  drivers/pci/controller/dwc/pci-keystone.c      |  5 ++---
> > >  .../pci/controller/dwc/pcie-designware-host.c  |  9 ++++-----
> > >  drivers/pci/controller/dwc/pcie-uniphier.c     |  6 ++----
> > >  .../controller/mobiveil/pcie-mobiveil-host.c   | 15 ++++++---------
> > >  drivers/pci/controller/pci-aardvark.c          |  5 ++---
> > >  drivers/pci/controller/pci-ftpci100.c          |  2 +-
> > >  drivers/pci/controller/pci-tegra.c             |  8 +++-----
> > >  drivers/pci/controller/pci-xgene-msi.c         |  9 +++------
> > >  drivers/pci/controller/pcie-altera-msi.c       | 10 ++++------
> > >  drivers/pci/controller/pcie-altera.c           | 10 ++++------
> > >  drivers/pci/controller/pcie-brcmstb.c          |  9 ++++-----
> > >  drivers/pci/controller/pcie-iproc-msi.c        |  4 +---
> > >  drivers/pci/controller/pcie-mediatek-gen3.c    | 13 ++++---------
> > >  drivers/pci/controller/pcie-mediatek.c         | 12 ++++--------
> > >  drivers/pci/controller/pcie-microchip-host.c   | 18 +++++++-----------
> > >  drivers/pci/controller/pcie-rcar-host.c        |  8 +++-----
> > >  drivers/pci/controller/pcie-rockchip-host.c    |  8 +++-----
> > >  drivers/pci/controller/pcie-xilinx-cpm.c       |  4 ++--
> > >  drivers/pci/controller/pcie-xilinx-nwl.c       | 13 +++----------
> > >  drivers/pci/controller/pcie-xilinx.c           |  9 ++++-----
> > >  21 files changed, 71 insertions(+), 120 deletions(-)
> >
> >
> > > diff --git a/drivers/pci/controller/pci-xgene-msi.c b/drivers/pci/controller/pci-xgene-msi.c
> > > index 1c34c897a7e2..cf3832b905e8 100644
> > > --- a/drivers/pci/controller/pci-xgene-msi.c
> > > +++ b/drivers/pci/controller/pci-xgene-msi.c
> > > @@ -291,8 +291,7 @@ static void xgene_msi_isr(struct irq_desc *desc)
> > >         struct irq_chip *chip = irq_desc_get_chip(desc);
> > >         struct xgene_msi_group *msi_groups;
> > >         struct xgene_msi *xgene_msi;
> > > -       unsigned int virq;
> > > -       int msir_index, msir_val, hw_irq;
> > > +       int msir_index, msir_val, hw_irq, ret;
> > >         u32 intr_index, grp_select, msi_grp;
> > >
> > >         chained_irq_enter(chip, desc);
> > > @@ -330,10 +329,8 @@ static void xgene_msi_isr(struct irq_desc *desc)
> > >                          * CPU0
> > >                          */
> > >                         hw_irq = hwirq_to_canonical_hwirq(hw_irq);
> > > -                       virq = irq_find_mapping(xgene_msi->inner_domain, hw_irq);
> > > -                       WARN_ON(!virq);
> > > -                       if (virq != 0)
> > > -                               generic_handle_irq(virq);
> > > +                       ret = generic_handle_domain_irq(xgene_msi->inner_domain, hw_irq);
> > > +                       WARN_ON(ret);
> >
> > There's various error prints in some of the handlers. I think they
> > should be moved to the core. I can't imagine handling the irq is ever
> > optional.
>
> Printing stuff like this is a sure recipe for disaster, and there is
> no way I'm moving such crap into core code.

Then why maintain such crap code? I'm fine with just removing. I just
think we should have some consistency.

> If the interrupt handling
> fails (most likely because there is no mapping for this interrupt), it
> is the driver's responsibility to handle the error (either disabling
> the input or the output of the secondary irqchip). There isn't much
> the core code can do about it.

I would imagine the errors here would be the 'this should never
happen' kind. Maybe a race with tearing down the domain. Seems to me
the core code should be warning when the calling code has made
mistakes.

Rob