[Xen-devel] Re: [PATCH 07/15] [swiotlb] In 'swiotlb_free' check iommu_sw pointer.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Jan 14, 2010 at 06:02:40PM -0800, Chris Wright wrote:
> * Konrad Rzeszutek Wilk (konrad.wilk@xxxxxxxxxx) wrote:
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -364,7 +364,7 @@ cleanup1:
> >  
> >  void __init swiotlb_free(void)
> >  {
> > -   if (!iommu_sw->overflow_buffer)
> > +   if (!iommu_sw)
> >             return;
> >  
> 
> Sure this is safe for the case where allocation failed?  Wouldn't this
> do free_late_bootmem(__pa(0))?

That would indeed fail, but alloc_bootmem_low_pages (___alloc_bootmem)
panics the machine if it can't allocate the buffer. So we would never
actually get to swiotlb_free if we failed to allocate the buffers for
SWIOTLB.

But for the case where the SWIOTLB allocation happens when using 
swiotlb_late_init_with_default_size, and it fails, this check
is not sufficient. I will add a check for that or just make
swiotlb_late_init_with_default_size set iommu_sw to NULL when
the allocation fails.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel