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

[Medvedkin, Vladimir]

Hi Kevin,

On 11/01/2022 17:15, Kevin Traynor wrote:
> 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 :-)
> 

Too bad that we are not working in a wheel 
(https://en.wikipedia.org/wiki/Wheel_theory), where division by 0 is 
always defined :)

>> ./dpdk-test-fib -- -n 9
>> ...
>> Floating point exception (core dumped)
>>
>> Fixes: 103809d032cd ("app/test-fib: add test application for FIB")
>> Cc: vladimir.medvedkin at intel.com
>>
> 
> You probably want to add 'Cc: stable at dpdk.org' for this.
> 
>> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin at 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?
> 

Agree, I'll send v2

>>           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;
>>           }
>>       }
>>
> 

-- 
Regards,
Vladimir