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Message-Id: <20231009074121.219686-4-hch@lst.de> Date: Mon, 9 Oct 2023 09:41:18 +0200 From: Christoph Hellwig <hch@....de> To: iommu@...ts.linux.dev Cc: Robin Murphy <robin.murphy@....com>, Marek Szyprowski <m.szyprowski@...sung.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, Wei Fang <wei.fang@....com>, Shenwei Wang <shenwei.wang@....com>, Clark Wang <xiaoning.wang@....com>, NXP Linux Team <linux-imx@....com>, linux-m68k@...ts.linux-m68k.org, netdev@...r.kernel.org, Jim Quinlan <james.quinlan@...adcom.com> Subject: [PATCH 3/6] 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: Christoph Hellwig <hch@....de> --- kernel/dma/direct.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index ec410af1d8a14e..1327d04fa32a25 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -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)) - return NULL; - set_uncached = true; - } + if (!set_uncached && !remap) + return NULL; } /* - * 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 */ -- 2.39.2
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