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

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Date:   Wed, 19 Sep 2018 10:35:55 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     lorenzo.pieralisi@....com
Cc:     Nathan Chancellor <natechancellor@...il.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>
Subject: Re: [PATCH] PCI: kirin: Fix section mismatch warning

On Wed, Sep 19, 2018 at 3:29 AM Lorenzo Pieralisi
<lorenzo.pieralisi@....com> wrote:
>
> Xiaowei, Binghui,
>
> On Tue, Sep 18, 2018 at 10:38:29PM -0700, Nathan Chancellor 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.
> >
> > Remove '__init' from kirin_add_pcie_port so there is no mismatch.
>
> I think that instead of removing __init section tag we should add
> it to kirin_pcie_probe().

A bunch of these functions have a single call site, with a mix of __init:

kirin_pcie_probe() ->
  kirin_add_pcie_port() ->  // __init
    kirin_pcie_add_msi()

But it looks like probe functions should be marked init:
$ cd drivers; grep -r __init | grep probe

seems to turn up quite a lot of *probe() functions that are marked __init.
https://www.tldp.org/LDP/lkmpg/2.4/html/x281.htm has more info, and
from reading that, it seems that it's a no-op for a module that's
marked loadable.

So I agree; __init should be added to kirin_pcie_probe(), but also
kirin_pcie_add_msi().  That way if the module is statically compiled
into the kernel image, these functions with a single call site get
cleaned up after init.

Nathan, would you mind sending a v2?

>
> Please let me know and ACK accordingly.
>
> Lorenzo
>
> > Fixes: fc5165db245a ("PCI: kirin: Add HiSilicon Kirin SoC PCIe controller driver")
> > Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-kirin.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
> > index 5352e0c3be82..9b599296205d 100644
> > --- a/drivers/pci/controller/dwc/pcie-kirin.c
> > +++ b/drivers/pci/controller/dwc/pcie-kirin.c
> > @@ -467,8 +467,8 @@ static int kirin_pcie_add_msi(struct dw_pcie *pci,
> >       return 0;
> >  }
> >
> > -static int __init kirin_add_pcie_port(struct dw_pcie *pci,
> > -                                   struct platform_device *pdev)
> > +static int kirin_add_pcie_port(struct dw_pcie *pci,
> > +                            struct platform_device *pdev)
> >  {
> >       int ret;
> >
> > --
> > 2.19.0
> >



-- 
Thanks,
~Nick Desaulniers