Commit c2f60aa1 authored by Takashi Sakamoto's avatar Takashi Sakamoto
Browse files

firewire: core: use common kernel API to allocate and release a batch of pages 

The pair of alloc_pages_bulk() and release_pages() are convenient to
allocate and release a batch of pages.

This commit utilizes the pair to maintain pages for isochronous DMA
context.

Link: https://lore.kernel.org/r/20260110013911.19160-5-o-takashi@sakamocchi.jp


Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
parent a69a9e63

drivers/firewire/core-iso.c

+12 −14
Original line number Diff line number Diff line
@@ -31,22 +31,18 @@ 
int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count)

{

	struct page **page_array __free(kfree) = kcalloc(page_count, sizeof(page_array[0]), GFP_KERNEL);

	int i;



	if (!page_array)

		return -ENOMEM;



	for (i = 0; i < page_count; ++i) {

		struct page *page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);



		if (!page)

			break;

		page_array[i] = page;

	}



	if (i < page_count) {

		while (i-- > 0)

			__free_page(page_array[i]);

	// Retrieve noncontiguous pages. The descriptors for 1394 OHCI isochronous DMA contexts

	// have a set of address and length per each, while the reason to use pages is the

	// convenience to map them into virtual address space of user process.

	unsigned long nr_populated = alloc_pages_bulk(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO,

						      page_count, page_array);

	if (nr_populated != page_count) {

		// Assuming the above call fills page_array sequentially from the beginning.

		release_pages(page_array, nr_populated);

		return -ENOMEM;

	}
@@ -64,7 +60,10 @@ int fw_iso_buffer_map_dma(struct fw_iso_buffer *buffer, struct fw_card *card, 


	buffer->direction = direction;



	// Retrieve DMA mapping addresses for the pages. They are not contiguous. Maintain the cache

	// coherency for the pages by hand.

	for (i = 0; i < buffer->page_count; i++) {

		// The dma_map_phys() with a physical address per page is available here, instead.

		address = dma_map_page(card->device, buffer->pages[i],

				       0, PAGE_SIZE, direction);

		if (dma_mapping_error(card->device, address))
@@ -109,8 +108,7 @@ void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer, 
	}



	if (buffer->pages) {

		for (int i = 0; i < buffer->page_count; ++i)

			__free_page(buffer->pages[i]);

		release_pages(buffer->pages, buffer->page_count);

		kfree(buffer->pages);

		buffer->pages = NULL;

	}