linux-kernel - [PATCH 1/9] sparc/iommu: use !PageHighMem to check if a page has a kernel mapping

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Message-Id: <20190416182347.18441-2-hch@lst.de>
Date:   Tue, 16 Apr 2019 20:23:39 +0200
From:   Christoph Hellwig <hch@....de>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Guenter Roeck <linux@...ck-us.net>, sparclinux@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/9] sparc/iommu: use !PageHighMem to check if a page has a kernel mapping

This deobsfucates the check a bit, and prepares for future changes.

Signed-off-by: Christoph Hellwig <hch@....de>
Reported-by: Guenter Roeck <linux@...ck-us.net>
---
 arch/sparc/mm/iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/sparc/mm/iommu.c b/arch/sparc/mm/iommu.c
index e8d5d73ca40d..dcdadac03fdf 100644
--- a/arch/sparc/mm/iommu.c
+++ b/arch/sparc/mm/iommu.c
@@ -273,7 +273,8 @@ static int sbus_iommu_map_sg_pflush(struct device *dev, struct scatterlist *sgl,
 		 * XXX Is this a good assumption?
 		 * XXX What if someone else unmaps it here and races us?
 		 */
-		if ((page = (unsigned long) page_address(sg_page(sg))) != 0) {
+		if (!PageHighMem(sg_page(sg))) {
+			page = (unsigned long)page_address(sg_page(sg));
 			for (i = 0; i < n; i++) {
 				if (page != oldpage) {	/* Already flushed? */
 					flush_page_for_dma(page);
-- 
2.20.1