linux-kernel - Re: [PATCH v2] staging: comedi: resolve section mismatch in s626

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Message-ID: <20120420013411.GA3769@cantor.Home>
Date:	Thu, 19 Apr 2012 18:34:11 -0700
From:	Gerard Snitselaar <dev@...tselaar.org>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	Ian Abbott <abbotti@....co.uk>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	Ian Abbott <ian.abbott@....co.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"fmhess@...rs.sourceforge.net" <fmhess@...rs.sourceforge.net>
Subject: Re: [PATCH v2] staging: comedi: resolve section mismatch in s626

On Wed Apr 18 12, Greg KH wrote:
> On Thu, Apr 12, 2012 at 02:03:16PM +0100, Ian Abbott wrote:
> > On 2012/04/10 07:24 PM, Greg KH wrote:
> > >On Mon, Apr 02, 2012 at 11:48:54AM +0100, Ian Abbott wrote:
> > >>On 2012-03-19 23:26, Greg KH wrote:
> > >>>On Mon, Mar 19, 2012 at 03:46:49PM -0700, Gerard Snitselaar wrote:
> > >>>>I looked at this a bit more. It looks like they lose visibility to the
> > >>>>pci_dev structure.
> > >>>>
> > >>>>*_probe()
> > >>>>   comedi_pci_auto_config()     pci_dev
> > >>>>      comedi_auto_config()      pci_dev->dev
> > >>>>         comedi_device_attach() ??
> > >>>>            driv->attach()      ??<= iterate through pci devices.
> > >>>>
> > >>>>Most of the examples I have looked at so far use for_each_pci_dev() to
> > >>>>find the device, and s626 shortcuts it a bit by directly making calls
> > >>>>to pci_get_subsys() with specific ids. They all verify they have the
> > >>>>right device by checking the bus and slot that are grabbed from the
> > >>>>pci_dev in comedi_pci_auto_config() and passed down.
> > >>>
> > >>>Ugh, surely there's a way to keep the pci dev through the
> > >>>comedi_device_attach() call, right?
> > >>
> > >>comedi_device_attach() is also called for the COMEDI_DEVCONFIG ioctl
> > >>for "manually" configuring a comedi device, and that has no idea
> > >>about struct pci_dev, etc.
> > >>
> > >>I recently posted a series of patches that allows lower-level comedi
> > >>drivers to supply separate hooks for auto-configuring PCI devices or
> > >>USB devices without abusing the old "manual configuration" code
> > >>paths, see <http://driverdev.linuxdriverproject.org/pipermail/devel/2012-March/025331.html>.
> > >>
> > >>The old loop that searches the PCI bus is still needed for the
> > >>"manual configuration" code path.
> > >
> > >So, now that I've applied your patches, this patch isn't needed anymore,
> > >right?  Or should it be reworked to use the new interfaces?
> > 
> > I think it's still needed as that the comedi_driver->attach() hook
> > is still needed to support manual configuration by the
> > COMEDI_DEVCONFIG ioctl, and the existing code really shouldn't be
> > looking in s626_pci_table[] as it's tagged __devinitconst.
> > 
> > I never saw any mismatched section warnings when I compiled a
> > linux-next kernel on my system with a full set of comedi drivers,
> > even with CONFIG_DEBUG_SECTION_MISMATCH configured.  I'm not sure
> > why not, unless it has something to do with me building the kernel
> > with a separate build directory.
> 
> Yes, I don't see the mismatch either, so I'm not going to apply this
> patch, sorry, as I don't see what it is trying to fix at all.
> 
> greg k-h

I am getting an error when doing a build of the latest linux-next
before it gets to modpost so I need to look at that, but when I do an
allyesconfig build on master I get the following:

WARNING: drivers/staging/comedi/drivers/s626.o(.text+0x2ec8): Section mismatch in reference from the function s626_attach() to the variable .devinit.rodata:s626_pci_table
The function s626_attach() references
the variable __devinitconst s626_pci_table.
This is often because s626_attach lacks a __devinitconst 
annotation or the annotation of s626_pci_table is wrong.

WARNING: drivers/staging/comedi/drivers/s626.o(.text+0x2ece): Section mismatch in reference from the function s626_attach() to the variable .devinit.rodata:s626_pci_table
The function s626_attach() references
the variable __devinitconst s626_pci_table.
This is often because s626_attach lacks a __devinitconst 
annotation or the annotation of s626_pci_table is wrong.

WARNING: drivers/staging/comedi/drivers/s626.o(.text+0x2ed7): Section mismatch in reference from the function s626_attach() to the variable .devinit.rodata:s626_pci_table
The function s626_attach() references
the variable __devinitconst s626_pci_table.
This is often because s626_attach lacks a __devinitconst 
annotation or the annotation of s626_pci_table is wrong.

WARNING: drivers/staging/comedi/drivers/s626.o(.text+0x2edd): Section mismatch in reference from the function s626_attach() to the variable .devinit.rodata:s626_pci_table
The function s626_attach() references
the variable __devinitconst s626_pci_table.
This is often because s626_attach lacks a __devinitconst 
annotation or the annotation of s626_pci_table is wrong.
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