Re: [PATCH] Improve pci_alloc_consistent wrapper on preemptive kernels

[Andrew Morton <akpm@osdl.org>]

James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
>
> On Fri, 2004-07-30 at 16:02, Andrew Morton wrote:
> > We're paying for past sins here.  I think it would be better to create a
> > new version of pci_alloc_consistent() which takes gfp_flags, then migrate
> > the drivers you care about to use it.  That way the benefit is available on
> > non-preempt kernels too.
> > 
> > The ultimate aim of course would be to deprecate then remove the old
> > function.
> 
> True, that's why it was added for dma_alloc_coherent().
> 
> Is there any need for a new wrapper?  Why not just use
> dma_alloc_coherent() from now on?
> 

Sounds sane.  But the default version in asm-generic/dma-mapping.h needs to
be fixed up:

static inline void *
dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
		   int flag)
{
	BUG_ON(dev->bus != &pci_bus_type);

	return pci_alloc_consistent(to_pci_dev(dev), size, dma_handle);
}

If we stick with this model, we'll still need a new pci_alloc_consistent_gfp().