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Date: Mon, 24 May 2021 16:06:21 +0100
From: Marc Zyngier <maz@...nel.org>
To: Rob Herring <robh@...nel.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Ley Foon Tan <ley.foon.tan@...el.com>,
Chris Zankel <chris@...kel.net>,
Max Filippov <jcmvbkbc@...il.com>,
Vineet Gupta <vgupta@...opsys.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Robert Jarzmik <robert.jarzmik@...e.fr>,
Russell King <linux@...linux.org.uk>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Rob Clark <robdclark@...il.com>,
Linus Walleij <linus.walleij@...aro.org>,
Lee Jones <lee.jones@...aro.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [PATCH 30/39] PCI: Bulk conversion to generic_handle_domain_irq()
On Mon, 24 May 2021 14:28:42 +0100,
Rob Herring <robh@...nel.org> wrote:
>
> On Mon, May 24, 2021 at 3:38 AM Marc Zyngier <maz@...nel.org> wrote:
> >
> > On Thu, 20 May 2021 18:47:06 +0100,
> > Rob Herring <robh@...nel.org> wrote:
> > >
> > > On Thu, May 20, 2021 at 11:57 AM Marc Zyngier <maz@...nel.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@...nel.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.
Then by any mean, remove it. I'd even be tempted to say "remove the
driver", but there is an XGene-1 box right behind me...
>
> > 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.
The core code already returns an error, which is plenty. It doesn't
have the context to actually *do* anything, and I don't think moaning
on the console helps much.
The onus is firmly on the caller side to get their act together.
M.
--
Without deviation from the norm, progress is not possible.
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