Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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: Takashi Sakamoto <o-takashi@sakamocchi.jp>
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-14
+12
-14
drivers/firewire/core-iso.c
+12
-14
drivers/firewire/core-iso.c
···
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int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count)
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{
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struct page **page_array __free(kfree) = kcalloc(page_count, sizeof(page_array[0]), GFP_KERNEL);
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int i;
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if (!page_array)
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return -ENOMEM;
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for (i = 0; i < page_count; ++i) {
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struct page *page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
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if (!page)
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break;
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page_array[i] = page;
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}
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if (i < page_count) {
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while (i-- > 0)
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__free_page(page_array[i]);
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// Retrieve noncontiguous pages. The descriptors for 1394 OHCI isochronous DMA contexts
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// have a set of address and length per each, while the reason to use pages is the
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// convenience to map them into virtual address space of user process.
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unsigned long nr_populated = alloc_pages_bulk(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO,
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page_count, page_array);
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if (nr_populated != page_count) {
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// Assuming the above call fills page_array sequentially from the beginning.
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release_pages(page_array, nr_populated);
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return -ENOMEM;
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}
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···
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buffer->direction = direction;
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// Retrieve DMA mapping addresses for the pages. They are not contiguous. Maintain the cache
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// coherency for the pages by hand.
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for (i = 0; i < buffer->page_count; i++) {
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// The dma_map_phys() with a physical address per page is available here, instead.
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address = dma_map_page(card->device, buffer->pages[i],
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0, PAGE_SIZE, direction);
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if (dma_mapping_error(card->device, address))
···
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}
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if (buffer->pages) {
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for (int i = 0; i < buffer->page_count; ++i)
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__free_page(buffer->pages[i]);
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release_pages(buffer->pages, buffer->page_count);
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kfree(buffer->pages);
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buffer->pages = NULL;
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}