Re: [dpdk-dev] [PATCH] test: fix division by zero

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Apr 23, 2021 at 03:35:30PM +0800, Min Hu (Connor) wrote:
> Variable i is used as a denominator which may be zero, and
> this may result in segmentation fault.
> 
> This patch fixed it.
> 
> Fixes: 948bc3d6d095 ("test: add reciprocal based division")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> ---
>  app/test/test_reciprocal_division_perf.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/app/test/test_reciprocal_division_perf.c b/app/test/test_reciprocal_division_perf.c
> index a7be8aa..2647308 100644
> --- a/app/test/test_reciprocal_division_perf.c
> +++ b/app/test/test_reciprocal_division_perf.c
> @@ -143,7 +143,7 @@ test_reciprocal_division_perf(void)
>  					"result %"PRIu64"",
>  					nresult_u64, rresult_u64);
>  			result = 1;
> -			break;
> +			goto err;
>  		}
>  	}
>  
> @@ -182,7 +182,7 @@ test_reciprocal_division_perf(void)
>  					dividend_u64, divisor_u64,
>  					nresult_u64, rresult_u64);
>  			result = 1;
> -			break;
> +			goto err;
>  		}
>  	}
>  	printf("64bit Division results:\n");
> @@ -195,6 +195,7 @@ test_reciprocal_division_perf(void)
>  	printf("Cycles per division(reciprocal) : %3.2f\n",
>  			((double)tot_cyc_r)/i);
>  
> +err:
>  	return result;
>  }
>  
This looks correct as far as it goes, but I believe the same fix is needed
at lines 66 and 106 too.

One other thing I note is that currently the test will move on to the
next test case on failure, due to break, but using the goto will change
that behaviour. Therefore, I wonder if a better fix is to skip the
printouts if i == 0 in each case?

/Bruce