Re: [PATCH] app/test-fib: fix possible division by zero

[Kevin Traynor <ktraynor@redhat.com>]

On 23/12/2021 15:25, Vladimir Medvedkin wrote:
> This patch fixes the division by 0, which occurs if the number of routes is less than 10.
> Can be triggered by passing -n argument with value < 10:
> 

9 causing a divide by zero - another example of inflation :-)

> ./dpdk-test-fib -- -n 9
> ...
> Floating point exception (core dumped)
> 
> Fixes: 103809d032cd ("app/test-fib: add test application for FIB")
> Cc: vladimir.medvedkin@intel.com
> 

You probably want to add 'Cc: stable@dpdk.org' for this.

> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
> ---
>   app/test-fib/main.c | 40 ++++++++++++++++++++++++----------------
>   1 file changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/app/test-fib/main.c b/app/test-fib/main.c
> index ecd420116a..9bc8b8a7ca 100644
> --- a/app/test-fib/main.c
> +++ b/app/test-fib/main.c
> @@ -902,8 +902,9 @@ run_v4(void)
>   				return -ret;
>   			}
>   		}
> -		printf("AVG FIB add %"PRIu64"\n",
> -			(rte_rdtsc_precise() - start) / j);
> +		if (j != 0)
> +			printf("AVG FIB add %"PRIu64"\n",
> +				(rte_rdtsc_precise() - start) / j);


You are just not printing the result for these cases. Do you think it is 
worth to print a warning message (one), and update any documentation so 
the user is aware of the acceptable bounds?

>   		i += j;
>   	}
>   
> @@ -930,8 +931,9 @@ run_v4(void)
>   					return -ret;
>   				}
>   			}
> -			printf("AVG LPM add %"PRIu64"\n",
> -				(rte_rdtsc_precise() - start) / j);
> +			if (j != 0)
> +				printf("AVG LPM add %"PRIu64"\n",
> +					(rte_rdtsc_precise() - start) / j);
>   			i += j;
>   		}
>   	}
> @@ -984,8 +986,9 @@ run_v4(void)
>   		for (j = 0; j < (config.nb_routes - i) / k; j++)
>   			rte_fib_delete(fib, rt[i + j].addr, rt[i + j].depth);
>   
> -		printf("AVG FIB delete %"PRIu64"\n",
> -			(rte_rdtsc_precise() - start) / j);
> +		if (j != 0)
> +			printf("AVG FIB delete %"PRIu64"\n",
> +				(rte_rdtsc_precise() - start) / j);
>   		i += j;
>   	}
>   
> @@ -996,8 +999,9 @@ run_v4(void)
>   				rte_lpm_delete(lpm, rt[i + j].addr,
>   					rt[i + j].depth);
>   
> -			printf("AVG LPM delete %"PRIu64"\n",
> -				(rte_rdtsc_precise() - start) / j);
> +			if (j != 0)
> +				printf("AVG LPM delete %"PRIu64"\n",
> +					(rte_rdtsc_precise() - start) / j);
>   			i += j;
>   		}
>   	}
> @@ -1097,8 +1101,9 @@ run_v6(void)
>   				return -ret;
>   			}
>   		}
> -		printf("AVG FIB add %"PRIu64"\n",
> -			(rte_rdtsc_precise() - start) / j);
> +		if (j != 0)
> +			printf("AVG FIB add %"PRIu64"\n",
> +				(rte_rdtsc_precise() - start) / j);
>   		i += j;
>   	}
>   
> @@ -1125,8 +1130,9 @@ run_v6(void)
>   					return -ret;
>   				}
>   			}
> -			printf("AVG LPM add %"PRIu64"\n",
> -				(rte_rdtsc_precise() - start) / j);
> +			if (j != 0)
> +				printf("AVG LPM add %"PRIu64"\n",
> +					(rte_rdtsc_precise() - start) / j);
>   			i += j;
>   		}
>   	}
> @@ -1183,8 +1189,9 @@ run_v6(void)
>   		for (j = 0; j < (config.nb_routes - i) / k; j++)
>   			rte_fib6_delete(fib, rt[i + j].addr, rt[i + j].depth);
>   
> -		printf("AVG FIB delete %"PRIu64"\n",
> -			(rte_rdtsc_precise() - start) / j);
> +		if (j != 0)
> +			printf("AVG FIB delete %"PRIu64"\n",
> +				(rte_rdtsc_precise() - start) / j);
>   		i += j;
>   	}
>   
> @@ -1195,8 +1202,9 @@ run_v6(void)
>   				rte_lpm6_delete(lpm, rt[i + j].addr,
>   					rt[i + j].depth);
>   
> -			printf("AVG LPM delete %"PRIu64"\n",
> -				(rte_rdtsc_precise() - start) / j);
> +			if (j != 0)
> +				printf("AVG LPM delete %"PRIu64"\n",
> +					(rte_rdtsc_precise() - start) / j);
>   			i += j;
>   		}
>   	}
>