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From: Bjorn Helgaas <helgaas@kernel.org>
To: "Sergio M. Iglesias" <sergio@lony.xyz>
Cc: bhelgaas@google.com, lorenzo.pieralisi@arm.com, robh@kernel.org,
	kw@linux.com, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: About the "__refdata" tag in pci-keystone.c
Date: Mon, 27 Sep 2021 10:31:28 -0500	[thread overview]
Message-ID: <20210927153128.GA646260@bhelgaas> (raw)
In-Reply-To: <20210927103321.v4kod7xfiv5sreet@lony.xyz>

On Mon, Sep 27, 2021 at 12:33:21PM +0200, Sergio M. Iglesias wrote:
> Hello!
> 
> I have checked the "__refdata" tag that appears in the file
> "drivers/pci/controller/dwc/pci-keystone.c" and it is needed. The tag has
> been there since the creation of the file on commit 6e0832fa432e and
> nothing has changed since that would make it redundant.
> 
> The reason it is needed is because the struct references "ks_pcie_probe",
> which is a function tagged as "__init", so the compiler will most likely
> complain about the "__refdata" being removed.
> 
> Should I send a patch to add a comment explaining why it is a necessary
> tag as recommended in "include/linux/init.h"?
> > [...] so optimally document why the __ref is needed and why it's OK).

Thanks a lot for looking into this.

I'm not yet convinced that either the __init or the __refdata is
necessary.  If there is a reason, it would not be "to silence a
compiler complaint"; it would be something like "the keystone platform
is different from all the other platforms because the other platforms
support X but keystone does not."

Also, there are a couple other .probe() functions that are marked
__init:

  $ git grep "static int .*_pci.*_probe" drivers/pci | grep __init
  drivers/pci/controller/dwc/pci-keystone.c:static int __init ks_pcie_probe(struct platform_device *pdev)
  drivers/pci/controller/dwc/pci-layerscape-ep.c:static int __init ls_pcie_ep_probe(struct platform_device *pdev)
  drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c:static int __init ls_pcie_g4_probe(struct platform_device *pdev)
  drivers/pci/controller/pci-ixp4xx.c:static int __init ixp4xx_pci_probe(struct platform_device *pdev)

and their platform_driver structs are not marked __refdata:

  $ git grep "static struct platform_driver" drivers/pci | grep __refdata
  drivers/pci/controller/dwc/pci-keystone.c:static struct platform_driver ks_pcie_driver __refdata = {

I think this should all be more consistent: either all these __init
and __refdata annotations should be removed, or they should be used by
many more drivers.

Bjorn

  reply	other threads:[~2021-09-27 15:31 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 10:33 About the "__refdata" tag in pci-keystone.c Sergio M. Iglesias
2021-09-27 15:31 ` Bjorn Helgaas [this message]
2021-09-29 13:23   ` Rob Herring

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