linux-kernel - Re: linux-next: Tree for Aug 8 (not CONFIG_PCI

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Message-ID: <CAErSpo52KKY9mRc7wduFqYYpKQakEBa5KrJ0P3J9su6P5tJ6gQ@mail.gmail.com>
Date:	Mon, 12 Aug 2013 10:38:58 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Jason Cooper <jason@...edaemon.net>
Cc:	Randy Dunlap <rdunlap@...radead.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next list <linux-next@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci <linux-pci@...r.kernel.org>
Subject: Re: linux-next: Tree for Aug 8 (not CONFIG_PCI_MSI conflict)

On Mon, Aug 12, 2013 at 7:18 AM, Jason Cooper <jason@...edaemon.net> wrote:
> On Sat, Aug 10, 2013 at 08:01:49AM -0600, Bjorn Helgaas wrote:
>> On Fri, Aug 9, 2013 at 12:50 PM, Jason Cooper <jason@...edaemon.net> wrote:
>> > Randy,
>> >
>> > On Fri, Aug 09, 2013 at 09:41:38AM -0700, Randy Dunlap wrote:
>> >> On 08/09/13 07:59, Jason Cooper wrote:
>> >> > Randy,
>> >> >
>> >> > On Thu, Aug 08, 2013 at 01:03:04PM -0700, Randy Dunlap wrote:
>> >> >> On 08/08/13 00:08, Stephen Rothwell wrote:
>> >> >>> Hi all,
>> >> >>>
>> >> >>> Changes since 20130807:
>> >> >>>
>> >> >>
>> >> >> on i386 and x86_64:
>> >> >> when CONFIG_PCI_MSI is not enabled:
>> >> >>
>> >> >> There are many of these errors:
>> >> >> include/linux/msi.h:65:6: error: expected identifier or '(' before 'void'
>> >> >> include/linux/msi.h:65:6: error: expected ')' before numeric constant
>> >> >>
>> >> >> because arch/x86/include/asm/pci.h defines:
>> >> >> #define default_teardown_msi_irqs  NULL
>> >> >
>> >> > Do you have an example config you used?
>> >>
>> >> Sure, attached. (or I have 14 of them)
>> >
>> > Thanks, I was able to reproduce the error.  I'm not real familiar with
>> > this area of the code, but the relief is it doesn't appear to be caused
>> > by the mvebu changes (well, relief for us ;-) ).
>> >
>> > At any rate, give this a spin and see if it works for you
>> >
>> > If it's acceptable, I'll do an official patch for Bjorn.
>> >
>> > thx,
>> >
>> > Jason.
>> >
>> > ---------->8----------
>> > diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
>> > index d9e9e6c..6169414 100644
>> > --- a/arch/x86/include/asm/pci.h
>> > +++ b/arch/x86/include/asm/pci.h
>> > @@ -138,8 +138,8 @@ void default_restore_msi_irqs(struct pci_dev *dev, int irq);
>> >  #else
>> >  #define native_setup_msi_irqs          NULL
>> >  #define native_teardown_msi_irq                NULL
>> > -#define default_teardown_msi_irqs      NULL
>> > -#define default_restore_msi_irqs       NULL
>> > +void __weak default_teardown_msi_irqs(struct pci_dev *dev) { }
>> > +void __weak default_restore_msi_irqs(struct pci_dev *dev, int irq) { }
>>
>> I don't really like this solution of putting the empty implementation
>> in the header file, because then a weak body is generated in the
>> object of every source file that includes the header.
>>
>> default_teardown_msi_irqs() and default_restore_msi_irqs() seem like
>> fairly internal MSI functions, so I wonder why we need them defined at
>> all when CONFIG_PCI_MSI=n.  It seems like any uses of them should be
>> in code that's only compiled when CONFIG_PCI_MSI=y.  But I haven't
>> reproduced the problem and investigated yet.
>
> I first tried commenting out the definitions after reproducing the
> problem.  It also failed miserably.
>
> Please take a look at Thomas' latest MSI patch series,
>
>   [PATCHv9 01/10] PCI: use weak functions for MSI arch-specific functions
>
> I think his solution is much nicer than mine.

OK, I'll assume I don't need to do anything until I hear otherwise.

Bjorn
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