Re: [igt-dev] [Intel-gfx] [PATCH i-g-t] intel_gpu_top: Fix cleanup on old kernels / unsupported GPU

Tvrtko Ursulin
2023-01-23T10:24:07Z

On 20/01/2023 14:29, Das, Nirmoy wrote:
> Hi Tvrtko,
>
> On 1/19/2023 4:54 PM, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> Avoid trying to dereference null engines on exit when there are either
>> none which are supported, or kernel does not have i915 PMU support.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> ---
>>   tools/intel_gpu_top.c | 10 +++++++---
>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/intel_gpu_top.c b/tools/intel_gpu_top.c
>> index 7aa233570463..517dc2995d26 100644
>> --- a/tools/intel_gpu_top.c
>> +++ b/tools/intel_gpu_top.c
>> @@ -448,6 +448,9 @@ static void free_engines(struct engines *engines)
>>       };
>>       unsigned int i;
>> +    if (!engines)
>> +        return;
>> +
>
>
> This check should happen before the  struct pmu_counter free_list
> generation.

I could, but it doesn't have to, not sure what reasons for should you
have in mind?

Regards,

Tvrtko

>
> Regards,
>
> Nirmoy
>
>>       for (pmu = &free_list[0]; *pmu; pmu++) {
>>           if ((*pmu)->present)
>>               free((char *)(*pmu)->units);
>> @@ -2568,7 +2571,7 @@ int main(int argc, char **argv)
>>               "Failed to detect engines! (%s)\n(Kernel 4.16 or newer
>> is required for i915 PMU support.)\n",
>>               strerror(errno));
>>           ret = EXIT_FAILURE;
>> -        goto err;
>> +        goto err_engines;
>>       }
>>       ret = pmu_init(engines);
>> @@ -2585,7 +2588,7 @@ int main(int argc, char **argv)
>>   "More information can be found at 'Perf events and tool security'
>> document:\n"
>>
>> "https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html\n");
>>           ret = EXIT_FAILURE;
>> -        goto err;
>> +        goto err_pmu;
>>       }
>>       ret = EXIT_SUCCESS;
>> @@ -2699,8 +2702,9 @@ int main(int argc, char **argv)
>>           free_clients(clients);
>>       free(codename);
>> -err:
>> +err_pmu:
>>       free_engines(engines);
>> +err_engines:
>>       free(pmu_device);
>>   exit:
>>       igt_devices_free();