Re: [PATCH] sched: fix integer handling issue

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 2/23/2022 7:17 AM, Morten Brørup wrote:
>> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
>> Sent: Tuesday, 22 February 2022 17.03
>>
>> On Tue, 22 Feb 2022 15:13:53 +0100
>> Morten Brørup <mb@smartsharesystems.com> wrote:
>>
>>>> From: Megha Ajmera [mailto:megha.ajmera@intel.com]
>>>> Sent: Tuesday, 22 February 2022 14.19
>>>>
>>>> Masking of core mask was incorrect. Instead of using 1U for
>> shifting,
>>>> it
>>>> should be using 1LU as the result is assigned to uint64.
>>>>
>>>> CID 375859: Potentially overflowing expression "1U <<
>> app_main_core"
>>>> with
>>>> type "unsigned int" (32 bits, unsigned) is evaluated using 32-bit
>>>> arithmetic,
>>>> and then used in a context that expects an expression of type
>>>> "uint64_t"
>>>> (64 bits, unsigned).
>>>>
>>>> Coverity issue: 375859
>>>>
>>>> Signed-off-by: Megha Ajmera <megha.ajmera@intel.com>
>>>> ---
>>>>   examples/qos_sched/args.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/examples/qos_sched/args.c b/examples/qos_sched/args.c
>>>> index 10ca7bea61..44f2f5640e 100644
>>>> --- a/examples/qos_sched/args.c
>>>> +++ b/examples/qos_sched/args.c
>>>> @@ -433,7 +433,7 @@ app_parse_args(int argc, char **argv)
>>>>   			return -1;
>>>>   		}
>>>>   	}
>>>> -	app_used_core_mask |= 1u << app_main_core;
>>>> +	app_used_core_mask |= 1lu << app_main_core;
>>>
>>> Still wrong on 32 bit platforms, where long unsigned int is still 32
>> bits.
>>>
>>> Use this instead:
>>> app_used_core_mask |= RTE_BIT64(app_main_core);
>>
>> DPDK now supports > 64 lcores. So all code using/assuming a 64 bit mask
>> is broken.
>>
> 
> Good point. Is there a TODO-list where such a general review request can be filed, or should we just file it as a system-wide bug in Bugzilla?
> 
> Nonetheless, I think this one-line fix should be accepted as a short term solution.
> 

Hi Morten,

I suspect there can be more places that testpmd assumes
max core number is 64, someone needs to spend time to
analyze and fix it.