Re: [PATCH] tools: fix -Wunused-result in linux.c

[Shuah Khan <skhan@linuxfoundation.org>]

On 10/21/24 10:10, David Laight wrote:
> From: Liam R. Howlett
>> Sent: 15 October 2024 02:11
>>
>> * Shuah Khan <skhan@linuxfoundation.org> [241011 18:52]:
>>> Fix the following -Wunused-result warnings on posix_memalign()
>>> return values and add error handling.
>>>
>>> ./shared/linux.c:100:25: warning: ignoring return value of ‘posix_memalign’ declared with attribute
>> ‘warn_unused_result’ [-Wunused-result]
>>>    100 |          posix_memalign(&p, cachep->align, cachep->size);
>>>        |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ../shared/linux.c: In function ‘kmem_cache_alloc_bulk’:
>>> ../shared/linux.c:198:33: warning: ignoring return value of ‘posix_memalign’ declared with attribute
>> ‘warn_unused_result’ [-Wunused-result]
>>>    198 |          posix_memalign(&p[i], cachep->align,
>>>        |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>    199 |                                cachep->size);
>>>        |                                ~~~~~~~~~~~~~
>>>
>>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
>>
>> Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
>>
>>> ---
>>>   tools/testing/shared/linux.c | 14 +++++++++-----
>>>   1 file changed, 9 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c
>>> index 17263696b5d8..66dbb362385f 100644
>>> --- a/tools/testing/shared/linux.c
>>> +++ b/tools/testing/shared/linux.c
>>> @@ -96,10 +96,13 @@ void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
>>>   		p = node;
>>>   	} else {
>>>   		pthread_mutex_unlock(&cachep->lock);
>>> -		if (cachep->align)
>>> -			posix_memalign(&p, cachep->align, cachep->size);
>>> -		else
>>> +		if (cachep->align) {
>>> +			if (posix_memalign(&p, cachep->align, cachep->size) < 0)
>>> +				return NULL;
>>> +		} else {
>>>   			p = malloc(cachep->size);
>>> +		}
>>> +
> 
> You really ought to be checking malloc() as well.
> Perhaps:
> 		if (...) {
> 			if (posix_memalign(...) < 0)
> 				p = NULL;
> 		} else {
> 			p = malloc(...);
> 		}
> 		if (!p)
> 			return NULL;
> 
> Or just use a hack to get the compiler to STFU :-)

Yes you are right. I will spin another version to cover
the malloc and I just noticed another posix_memalign()
with -Wunused-result that compiler didn't flag in
kmem_cache_alloc_bulk() to fix as well in the next version.

thanks,
-- Shuah