[PATCH v3 1/4] dma-mapping: benchmark: Add padding to ensure uABI remained consistent

[Qinxin Xia <xiaqinxin@huawei.com>]

The padding field in the structure was previously reserved to
maintain a stable interface for potential new fields, ensuring
compatibility with user-space shared data structures.
However,it was accidentally removed by tiantao in a prior commit,
which may lead to incompatibility between user space and the kernel.

This patch reinstates the padding to restore the original structure
layout and preserve compatibility.

Fixes: 8ddde07a3d28 ("dma-mapping: benchmark: extract a common header file for map_benchmark definition")
Cc: stable@vger.kernel.org
Signed-off-by: Qinxin Xia <xiaqinxin@huawei.com>
---
 include/linux/map_benchmark.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/map_benchmark.h b/include/linux/map_benchmark.h
index 62674c83bde4..2ac2fe52f248 100644
--- a/include/linux/map_benchmark.h
+++ b/include/linux/map_benchmark.h
@@ -27,5 +27,6 @@ struct map_benchmark {
 	__u32 dma_dir; /* DMA data direction */
 	__u32 dma_trans_ns; /* time for DMA transmission in ns */
 	__u32 granule;  /* how many PAGE_SIZE will do map/unmap once a time */
+	__u8 expansion[76];     /* For future use */
 };
 #endif /* _KERNEL_DMA_BENCHMARK_H */
-- 
2.33.0