[PATCH] selftests/dma: fix invalid array access in printf

[PATCH] selftests/dma: fix invalid array access in printf

[Zhang Chujun]

The printf statement attempts to print the DMA direction string using
the syntax 'dir[directions]', which is an invalid array access. The
variable 'dir' is an integer, and 'directions' is a char pointer array.
This incorrect syntax should be 'directions[dir]', using 'dir' as the
index into the 'directions' array. Fix this by correcting the array
access from 'dir[directions]' to 'directions[dir]'.

Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com>

diff --git a/tools/testing/selftests/dma/dma_map_benchmark.c b/tools/testing/selftests/dma/dma_map_benchmark.c
index b12f1f9babf8..b925756373ce 100644
--- a/tools/testing/selftests/dma/dma_map_benchmark.c
+++ b/tools/testing/selftests/dma/dma_map_benchmark.c
@@ -118,7 +118,7 @@ int main(int argc, char **argv)
 	}
 
 	printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule: %d\n",
-			threads, seconds, node, dir[directions], granule);
+			threads, seconds, node, directions[dir], granule);
 	printf("average map latency(us):%.1f standard deviation:%.1f\n",
 			map.avg_map_100ns/10.0, map.map_stddev/10.0);
 	printf("average unmap latency(us):%.1f standard deviation:%.1f\n",
-- 
2.50.1.windows.1

Re: [PATCH] selftests/dma: fix invalid array access in printf

[Shuah Khan]

On 11/3/25 19:52, Zhang Chujun wrote:
> The printf statement attempts to print the DMA direction string using
> the syntax 'dir[directions]', which is an invalid array access. The
> variable 'dir' is an integer, and 'directions' is a char pointer array.
> This incorrect syntax should be 'directions[dir]', using 'dir' as the
> index into the 'directions' array. Fix this by correcting the array
> access from 'dir[directions]' to 'directions[dir]'.

How did you find this problem? The patch looks good to me, but
I do want to know how you found this because compiler doesn't
complain and I can build this fine.> 
> Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com>
> 
> diff --git a/tools/testing/selftests/dma/dma_map_benchmark.c b/tools/testing/selftests/dma/dma_map_benchmark.c
> index b12f1f9babf8..b925756373ce 100644
> --- a/tools/testing/selftests/dma/dma_map_benchmark.c
> +++ b/tools/testing/selftests/dma/dma_map_benchmark.c
> @@ -118,7 +118,7 @@ int main(int argc, char **argv)
>   	}
>   
>   	printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule: %d\n",
> -			threads, seconds, node, dir[directions], granule);
> +			threads, seconds, node, directions[dir], granule);
>   	printf("average map latency(us):%.1f standard deviation:%.1f\n",
>   			map.avg_map_100ns/10.0, map.map_stddev/10.0);
>   	printf("average unmap latency(us):%.1f standard deviation:%.1f\n",
thanks,
-- Shuah

[PATCH] selftests/dma: fix invalid array access in printf

[Zhang Chujun]

The printf statement attempts to print the DMA direction string using
the syntax 'dir[directions]', which is an invalid array access. The
variable 'dir' is an integer, and 'directions' is a char pointer array.
This incorrect syntax should be 'directions[dir]', using 'dir' as the
index into the 'directions' array. Fix this by correcting the array
access from 'dir[directions]' to 'directions[dir]'.

Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com>

diff --git a/tools/testing/selftests/dma/dma_map_benchmark.c b/tools/testing/selftests/dma/dma_map_benchmark.c
index b12f1f9babf8..b925756373ce 100644
--- a/tools/testing/selftests/dma/dma_map_benchmark.c
+++ b/tools/testing/selftests/dma/dma_map_benchmark.c
@@ -118,7 +118,7 @@ int main(int argc, char **argv)
 	}
 
 	printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule: %d\n",
-			threads, seconds, node, dir[directions], granule);
+			threads, seconds, node, directions[dir], granule);
 	printf("average map latency(us):%.1f standard deviation:%.1f\n",
 			map.avg_map_100ns/10.0, map.map_stddev/10.0);
 	printf("average unmap latency(us):%.1f standard deviation:%.1f\n",
-- 
2.50.1.windows.1

Re: [PATCH] selftests/dma: fix invalid array access in printf

[Shuah Khan]

On 11/5/25 20:30, Zhang Chujun wrote:
> The printf statement attempts to print the DMA direction string using
> the syntax 'dir[directions]', which is an invalid array access. The
> variable 'dir' is an integer, and 'directions' is a char pointer array.
> This incorrect syntax should be 'directions[dir]', using 'dir' as the
> index into the 'directions' array. Fix this by correcting the array
> access from 'dir[directions]' to 'directions[dir]'.
> 
> Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com>
> 
> diff --git a/tools/testing/selftests/dma/dma_map_benchmark.c b/tools/testing/selftests/dma/dma_map_benchmark.c
> index b12f1f9babf8..b925756373ce 100644
> --- a/tools/testing/selftests/dma/dma_map_benchmark.c
> +++ b/tools/testing/selftests/dma/dma_map_benchmark.c
> @@ -118,7 +118,7 @@ int main(int argc, char **argv)
>   	}
>   
>   	printf("dma mapping benchmark: threads:%d seconds:%d node:%d dir:%s granule: %d\n",
> -			threads, seconds, node, dir[directions], granule);
> +			threads, seconds, node, directions[dir], granule);
>   	printf("average map latency(us):%.1f standard deviation:%.1f\n",
>   			map.avg_map_100ns/10.0, map.map_stddev/10.0);
>   	printf("average unmap latency(us):%.1f standard deviation:%.1f\n",

Looks like you sent the same patch again. I replied to your previous
patch asking you how you found this problem. It looks like a needed
change. Compiler doesn't complain about it which is strange.

thanks,
-- Shuah