Commit b1da46d7 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-direct: simplify the use atomic pool logic in dma_direct_alloc 



The logic in dma_direct_alloc when to use the atomic pool vs remapping
grew a bit unreadable.  Consolidate it into a single check, and clean
up the set_uncached vs remap logic a bit as well.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
Reviewed-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
Tested-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
parent 2c8ed1b9

kernel/dma/direct.c

+10 −15
Original line number Diff line number Diff line
@@ -234,27 +234,22 @@ void *dma_direct_alloc(struct device *dev, size_t size, 
					dma_handle);



		/*

		 * Otherwise remap if the architecture is asking for it.  But

		 * given that remapping memory is a blocking operation we'll

		 * instead have to dip into the atomic pools.

		 * Otherwise we require the architecture to either be able to

		 * mark arbitrary parts of the kernel direct mapping uncached,

		 * or remapped it uncached.

		 */

		set_uncached = IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED);

		remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP);

		if (remap) {

			if (dma_direct_use_pool(dev, gfp))

				return dma_direct_alloc_from_pool(dev, size,

						dma_handle, gfp);

		} else {

			if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED))

		if (!set_uncached && !remap)

			return NULL;

			set_uncached = true;

		}

	}



	/*

	 * Decrypting memory may block, so allocate the memory from the atomic

	 * pools if we can't block.

	 * Remapping or decrypting memory may block, allocate the memory from

	 * the atomic pools instead if we aren't allowed block.

	 */

	if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))

	if ((remap || force_dma_unencrypted(dev)) &&

	    dma_direct_use_pool(dev, gfp))

		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);



	/* we always manually zero the memory once we are done */