linux-kernel - [PATCH] dma-direct: cleanup parameters to dma_direct_optimal_gfp

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Date:   Mon, 20 Feb 2023 16:06:22 +0100
From:   Petr Tesarik <petrtesarik@...weicloud.com>
To:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux.dev (open list:DMA MAPPING HELPERS),
        linux-kernel@...r.kernel.org (open list)
Cc:     roberto.sassu@...weicloud.com,
        Petr Tesarik <petrtesarik@...weicloud.com>
Subject: [PATCH] dma-direct: cleanup parameters to dma_direct_optimal_gfp_mask

Since both callers of dma_direct_optimal_gfp_mask() pass
dev->coherent_dma_mask as the second argument, it is better to
remove that parameter altogether.

Not only is reducing number of parameters good for readability, but
the new function signature is also more logical: The optimal flags
depend only on data contained in struct device.

While touching this code, let's also rename phys_mask to phys_limit
in dma_direct_alloc_from_pool(), because it is indeed a limit.

Signed-off-by: Petr Tesarik <petrtesarik@...weicloud.com>
---
 kernel/dma/direct.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 63859a101ed8..5595d1d5cdcc 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -44,10 +44,11 @@ u64 dma_direct_get_required_mask(struct device *dev)
 	return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
 }
 
-static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
-				  u64 *phys_limit)
+static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit)
 {
-	u64 dma_limit = min_not_zero(dma_mask, dev->bus_dma_limit);
+	u64 dma_limit = min_not_zero(
+		dev->coherent_dma_mask,
+		dev->bus_dma_limit);
 
 	/*
 	 * Optimistically try the zone that the physical address mask falls
@@ -126,8 +127,7 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 	if (is_swiotlb_for_alloc(dev))
 		return dma_direct_alloc_swiotlb(dev, size);
 
-	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
-					   &phys_limit);
+	gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
 	page = dma_alloc_contiguous(dev, size, gfp);
 	if (page) {
 		if (!dma_coherent_ok(dev, page_to_phys(page), size) ||
@@ -172,14 +172,13 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, gfp_t gfp)
 {
 	struct page *page;
-	u64 phys_mask;
+	u64 phys_limit;
 	void *ret;
 
 	if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_DMA_COHERENT_POOL)))
 		return NULL;
 
-	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
-					   &phys_mask);
+	gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
 	page = dma_alloc_from_pool(dev, size, &ret, gfp, dma_coherent_ok);
 	if (!page)
 		return NULL;
-- 
2.25.1