linux-kernel - [PATCH 38/67] x86/amd_gart: clean up gart_alloc

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Date:   Fri, 29 Dec 2017 09:18:42 +0100
From:   Christoph Hellwig <hch@....de>
To:     iommu@...ts.linux-foundation.org
Cc:     linux-alpha@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        adi-buildroot-devel@...ts.sourceforge.net,
        linux-c6x-dev@...ux-c6x.org, linux-cris-kernel@...s.com,
        linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-metag@...r.kernel.org,
        Michal Simek <monstr@...str.eu>, linux-mips@...ux-mips.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        patches@...ups.riscv.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        Guan Xuetao <gxt@...c.pku.edu.cn>, x86@...nel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 38/67] x86/amd_gart: clean up gart_alloc_coherent

Don't rely on the gfp mask from dma_alloc_coherent_gfp_flags to make the
fallback decision, and streamline the code flow a bit.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/x86/kernel/amd_gart_64.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index 52e3abcf3e70..92054815023e 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -484,26 +484,26 @@ gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
 	unsigned long align_mask;
 	struct page *page;
 
-	if (force_iommu && !(flag & GFP_DMA)) {
-		flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
-		page = alloc_pages(flag | __GFP_ZERO, get_order(size));
-		if (!page)
-			return NULL;
-
-		align_mask = (1UL << get_order(size)) - 1;
-		paddr = dma_map_area(dev, page_to_phys(page), size,
-				     DMA_BIDIRECTIONAL, align_mask);
-
-		flush_gart();
-		if (paddr != bad_dma_addr) {
-			*dma_addr = paddr;
-			return page_address(page);
-		}
-		__free_pages(page, get_order(size));
-	} else
+	if (!force_iommu || dev->coherent_dma_mask <= DMA_BIT_MASK(24))
 		return dma_direct_alloc(dev, size, dma_addr, flag, attrs);
 
-	return NULL;
+	flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
+	page = alloc_pages(flag | __GFP_ZERO, get_order(size));
+	if (!page)
+		return NULL;
+
+	align_mask = (1UL << get_order(size)) - 1;
+	paddr = dma_map_area(dev, page_to_phys(page), size, DMA_BIDIRECTIONAL,
+			align_mask);
+
+	flush_gart();
+	if (unlikely(paddr == bad_dma_addr)) {
+		__free_pages(page, get_order(size));
+		return NULL;
+	}
+
+	*dma_addr = paddr;
+	return page_address(page);
 }
 
 /* free a coherent mapping */
-- 
2.14.2