dma-mapping: refactor dma_{alloc,free}_pages

Factour out internal versions without the dma_debug calls in preparation
for callers that will need different dma_debug calls.

Note that this changes the dma_debug calls to get the not page aligned
size values, but as long as alloc and free agree on one variant we are
fine.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Ricardo Ribalda <ribalda@chromium.org>

kernel/dma/mapping.c

@@ -477,11 +477,10 @@ void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 }
 EXPORT_SYMBOL(dma_free_attrs);
 
-struct page *dma_alloc_pages(struct device *dev, size_t size,
+static struct page *__dma_alloc_pages(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
-	struct page *page;
 
 	if (WARN_ON_ONCE(!dev->coherent_dma_mask))
 		return NULL;
@@ -490,31 +489,41 @@ struct page *dma_alloc_pages(struct device *dev, size_t size,
 
 	size = PAGE_ALIGN(size);
 	if (dma_alloc_direct(dev, ops))
-		page = dma_direct_alloc_pages(dev, size, dma_handle, dir, gfp);
-	else if (ops->alloc_pages)
-		page = ops->alloc_pages(dev, size, dma_handle, dir, gfp);
-	else
+		return dma_direct_alloc_pages(dev, size, dma_handle, dir, gfp);
+	if (!ops->alloc_pages)
 		return NULL;
+	return ops->alloc_pages(dev, size, dma_handle, dir, gfp);
+}
 
-	debug_dma_map_page(dev, page, 0, size, dir, *dma_handle);
+struct page *dma_alloc_pages(struct device *dev, size_t size,
+		dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
+{
+	struct page *page = __dma_alloc_pages(dev, size, dma_handle, dir, gfp);
 
+	if (page)
+		debug_dma_map_page(dev, page, 0, size, dir, *dma_handle);
 	return page;
 }
 EXPORT_SYMBOL_GPL(dma_alloc_pages);
 
-void dma_free_pages(struct device *dev, size_t size, struct page *page,
+static void __dma_free_pages(struct device *dev, size_t size, struct page *page,
 		dma_addr_t dma_handle, enum dma_data_direction dir)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
 	size = PAGE_ALIGN(size);
-	debug_dma_unmap_page(dev, dma_handle, size, dir);
-
 	if (dma_alloc_direct(dev, ops))
 		dma_direct_free_pages(dev, size, page, dma_handle, dir);
 	else if (ops->free_pages)
 		ops->free_pages(dev, size, page, dma_handle, dir);
 }
+
+void dma_free_pages(struct device *dev, size_t size, struct page *page,
+		dma_addr_t dma_handle, enum dma_data_direction dir)
+{
+	debug_dma_unmap_page(dev, dma_handle, size, dir);
+	__dma_free_pages(dev, size, page, dma_handle, dir);
+}
 EXPORT_SYMBOL_GPL(dma_free_pages);
 
 int dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,