Re: [PATCH 1/1] device.h: arm,dma-iommu: Move out dma_iommu_mapping struct

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 05, 2014 at 12:16:28AM +0530, Ritesh Harjani wrote:
> >> --- a/include/linux/device.h
> >> +++ b/include/linux/device.h
> >> @@ -705,6 +705,10 @@ struct device {
> >>       /* arch specific additions */
> >>       struct dev_archdata     archdata;
> >>
> >> +#ifdef CONFIG_DMA_USE_IOMMU_HELPER_MAPPING
> >> +     struct dma_iommu_mapping        *mapping;
> >> +#endif
> >> +
> >>       struct device_node      *of_node; /* associated device tree node */
> >>       struct acpi_dev_node    acpi_node; /* associated ACPI device node */
> >>
> >
> > Are you sure this will not break the build on systems that enable that
> > option, yet do not include iommu-helper.h?
> 
> They need to include iommu-helper.h wherever they are using this
> structure members. Until then no this should
> not break the build I think for the case you mentioned.

Try it and find out :)

> That's how it was done in arch/arm/include/asm/device.h

Perhaps something else was pulling in that .h file?  device.h is used
_everywhere_ you can not assume someone will have included another .h
file before it.

> Do I need to do this in diff way ?

Yes, just predefine the structure in the .h file.

And do you really need the #ifdef?

thanks,

greg k-h