linux-kernel - Re: [PATCH v2] PCI: kirin: Fix section mismatch warning

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Message-ID: <20181001164410.GA14767@e107981-ln.cambridge.arm.com>
Date:   Mon, 1 Oct 2018 17:44:10 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        songxiaowei@...ilicon.com, wangbinghui@...ilicon.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        paul.gortmaker@...driver.com
Subject: Re: [PATCH v2] PCI: kirin: Fix section mismatch warning

On Mon, Oct 01, 2018 at 08:12:05AM -0700, Nathan Chancellor wrote:
> On Mon, Oct 01, 2018 at 03:53:41PM +0100, Lorenzo Pieralisi wrote:
> > On Thu, Sep 20, 2018 at 11:58:28AM +0100, Lorenzo Pieralisi wrote:
> > > [+Paul]
> > > 
> > > On Wed, Sep 19, 2018 at 02:08:08PM -0700, Nick Desaulniers wrote:
> > > > On Wed, Sep 19, 2018 at 11:55 AM Nathan Chancellor
> > > > <natechancellor@...il.com> wrote:
> > > > >
> > > > > WARNING: vmlinux.o(.text+0x4758cc): Section mismatch in reference from
> > > > > the function kirin_pcie_probe() to the function
> > > > > .init.text:kirin_add_pcie_port()
> > > > > The function kirin_pcie_probe() references
> > > > > the function __init kirin_add_pcie_port().
> > > > > This is often because kirin_pcie_probe lacks a __init
> > > > > annotation or the annotation of kirin_add_pcie_port is wrong.
> > > > >
> > > > > Add the __init annotation to both kirin_pcie_probe and
> > > > > kirin_pcie_add_msi then use builtin_platform_driver_probe
> > > > > instead of builtin_platform_driver + .probe to avoid a section
> > > > > mismatch warning with kirin_pcie_driver.
> > > > >
> > > > > Fixes: fc5165db245a ("PCI: kirin: Add HiSilicon Kirin SoC PCIe controller driver")
> > > > > Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > > > Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > > > Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> > > > > ---
> > > > >
> > > > > v1 -> v2:
> > > > >
> > > > > Instead of removing the annotation on kirin_add_pcie_port, add it to
> > > > > kirin_pcie_add_msi and kirin_pcie_probe. To avoid a warning with this
> > > > > configuration, use builtin_platform_driver_probe.
> > > > >
> > > > >  drivers/pci/controller/dwc/pcie-kirin.c | 9 ++++-----
> > > > >  1 file changed, 4 insertions(+), 5 deletions(-)
> > > > >
> > > > > diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
> > > > > index 5352e0c3be82..f64fed12de51 100644
> > > > > --- a/drivers/pci/controller/dwc/pcie-kirin.c
> > > > > +++ b/drivers/pci/controller/dwc/pcie-kirin.c
> > > > > @@ -448,8 +448,8 @@ static const struct dw_pcie_host_ops kirin_pcie_host_ops = {
> > > > >         .host_init = kirin_pcie_host_init,
> > > > >  };
> > > > >
> > > > > -static int kirin_pcie_add_msi(struct dw_pcie *pci,
> > > > > -                               struct platform_device *pdev)
> > > > > +static int __init kirin_pcie_add_msi(struct dw_pcie *pci,
> > > > > +                                    struct platform_device *pdev)
> > > > >  {
> > > > >         int irq;
> > > > >
> > > > > @@ -481,7 +481,7 @@ static int __init kirin_add_pcie_port(struct dw_pcie *pci,
> > > > >         return dw_pcie_host_init(&pci->pp);
> > > > >  }
> > > > >
> > > > > -static int kirin_pcie_probe(struct platform_device *pdev)
> > > > > +static int __init kirin_pcie_probe(struct platform_device *pdev)
> > > > >  {
> > > > >         struct device *dev = &pdev->dev;
> > > > >         struct kirin_pcie *kirin_pcie;
> > > > > @@ -533,11 +533,10 @@ static const struct of_device_id kirin_pcie_match[] = {
> > > > >  };
> > > > >
> > > > >  static struct platform_driver kirin_pcie_driver = {
> > > > > -       .probe                  = kirin_pcie_probe,
> > > > >         .driver                 = {
> > > > >                 .name                   = "kirin-pcie",
> > > > >                 .of_match_table = kirin_pcie_match,
> > > > >                 .suppress_bind_attrs = true,
> > > > >         },
> > > > >  };
> > > > > -builtin_platform_driver(kirin_pcie_driver);
> > > > > +builtin_platform_driver_probe(kirin_pcie_driver, kirin_pcie_probe);
> > > > 
> > > > It would be good to get additional review from someone who knows more
> > > > about driver callback lifecycles, but I think this is the correct fix.
> > > > Thanks Nathan.
> > > > Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > 
> > > AFAICS we can't use builtin_platform_driver_probe() if the probe()
> > > itself may need deferral (and I *reckon* it may need that, see eg
> > > clk_get()) so I suspect we have to go back to v1 for the patch,
> > > apologies if so.
> > 
> > I think that the best course of action consists in merging v1 since
> > we have not reached a definitive conclusion on v2, please let me
> > know.
> > 
> > Thanks,
> > Lorenzo
> 
> Hi Lorenzo,
> 
> I am perfectly fine with v1 being merged as either patch solves the
> warning. I agree with Nick that if this version works it would be more
> proper but it also carries more risk with regards to deferral like you
> stated. Please let me know if I need to resend it.

I have applied v1 to my pci/dwc for v4.20 and dropped this patch, thanks
for bearing with me and if there is any objection please let me know.

Thanks,
Lorenzo