linux-kernel - [PATCH AUTOSEL 6.9 02/23] dma-mapping: benchmark: avoid needless copy_to

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Date: Wed,  5 Jun 2024 08:01:45 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Fedor Pchelkin <pchelkin@...ras.ru>,
	Barry Song <21cnbao@...il.com>,
	Robin Murphy <robin.murphy@....com>,
	Christoph Hellwig <hch@....de>,
	Sasha Levin <sashal@...nel.org>,
	chenxiang66@...ilicon.com,
	m.szyprowski@...sung.com,
	iommu@...ts.linux.dev
Subject: [PATCH AUTOSEL 6.9 02/23] dma-mapping: benchmark: avoid needless copy_to_user if benchmark fails

From: Fedor Pchelkin <pchelkin@...ras.ru>

[ Upstream commit f7c9ccaadffd13066353332c13d7e9bf73b8f92d ]

If do_map_benchmark() has failed, there is nothing useful to copy back
to userspace.

Suggested-by: Barry Song <21cnbao@...il.com>
Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>
Acked-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/dma/map_benchmark.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
index 02205ab53b7e9..28ca165cb62c1 100644
--- a/kernel/dma/map_benchmark.c
+++ b/kernel/dma/map_benchmark.c
@@ -252,6 +252,9 @@ static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
 		 * dma_mask changed by benchmark
 		 */
 		dma_set_mask(map->dev, old_dma_mask);
+
+		if (ret)
+			return ret;
 		break;
 	default:
 		return -EINVAL;
-- 
2.43.0