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

Aaro Koskinen
2012-02-21T21:30:15Z

Hi,

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?

> + mutex_lock(&cma_mutex);
> + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
> + free_contig_range(pfn, count);
> + mutex_unlock(&cma_mutex);
> +
> + return true;
> +}

A.