[PATCH 3/4] dma-direct: clean up the remapping checks in dma_direct_alloc

[Christoph Hellwig <hch@lst.de>]

Add a local variable to track if we want to remap the returned address
using vmap and use that to simplify the code flow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 kernel/dma/direct.c | 44 +++++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 6673f7aebf787..41498243d8444 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -166,6 +166,7 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
 void *dma_direct_alloc(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
+	bool remap = false;
 	struct page *page;
 	void *ret;
 	int err;
@@ -218,9 +219,23 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	if (!page)
 		return NULL;
 
-	if ((IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-	     !dev_is_dma_coherent(dev)) ||
-	    (IS_ENABLED(CONFIG_DMA_REMAP) && PageHighMem(page))) {
+	if (!dev_is_dma_coherent(dev) && IS_ENABLED(CONFIG_DMA_DIRECT_REMAP)) {
+		remap = true;
+	} else if (PageHighMem(page)) {
+		/*
+		 * Depending on the cma= arguments and per-arch setup,
+		 * dma_alloc_contiguous could return highmem pages.
+		 * Without remapping there is no way to return them here, so
+		 * log an error and fail.
+		 */
+		if (!IS_ENABLED(CONFIG_DMA_REMAP)) {
+			dev_info(dev, "Rejecting highmem page from CMA.\n");
+			goto out_free_pages;
+		}
+		remap = true;
+	}
+
+	if (remap) {
 		/* remove any dirty cache lines on the kernel alias */
 		arch_dma_prep_coherent(page, size);
 
@@ -230,36 +245,23 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 				__builtin_return_address(0));
 		if (!ret)
 			goto out_free_pages;
-		err = dma_set_decrypted(dev, ret, size);
-		memset(ret, 0, size);
-		goto done;
+	} else {
+		ret = page_address(page);
 	}
 
-	if (PageHighMem(page)) {
-		/*
-		 * Depending on the cma= arguments and per-arch setup
-		 * dma_alloc_contiguous could return highmem pages.
-		 * Without remapping there is no way to return them here,
-		 * so log an error and fail.
-		 */
-		dev_info(dev, "Rejecting highmem page from CMA.\n");
-		goto out_free_pages;
-	}
-
-	ret = page_address(page);
 	err = dma_set_decrypted(dev, ret, size);
 	if (err)
 		goto out_free_pages;
 	memset(ret, 0, size);
 
-	if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
-	    !dev_is_dma_coherent(dev)) {
+	if (!remap && !dev_is_dma_coherent(dev) &&
+	    IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED)) {
 		arch_dma_prep_coherent(page, size);
 		ret = arch_dma_set_uncached(ret, size);
 		if (IS_ERR(ret))
 			goto out_encrypt_pages;
 	}
-done:
+
 	*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
 	return ret;
 
-- 
2.30.2

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