RE: [PATCHv22 13/16] drivers: add Contiguous Memory Allocator

Marek Szyprowski
2012-02-22T16:27:03Z

Hello,

On Tuesday, February 21, 2012 10:30 PM Aaro Koskinen wrote:

> On Fri, 17 Feb 2012, Marek Szyprowski wrote:
> > +/**
> > + * dma_release_from_contiguous() - release allocated pages
> > + * @dev: Pointer to device for which the pages were allocated.
> > + * @pages: Allocated pages.
> > + * @count: Number of allocated pages.
> > + *
> > + * This function releases memory allocated by dma_alloc_from_contiguous().
> > + * It returns false when provided pages do not belong to contiguous area and
> > + * true otherwise.
> > + */
> > +bool dma_release_from_contiguous(struct device *dev, struct page *pages,
> > + int count)
> > +{
> > + struct cma *cma = dev_get_cma_area(dev);
> > + unsigned long pfn;
> > +
> > + if (!cma || !pages)
> > + return false;
> > +
> > + pr_debug("%s(page %p)\n", __func__, (void *)pages);
> > +
> > + pfn = page_to_pfn(pages);
> > +
> > + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
> > + return false;
> > +
> > + VM_BUG_ON(pfn + count > cma->base_pfn);
>
> Are you sure the VM_BUG_ON() condition is correct here?

Thanks for pointing this bug. '+ cma->count' is missing in the second part.

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center