Re: [kvm-unit-tests PATCH v2] alloc: Add memalign error checks

[Janosch Frank <frankja@linux.ibm.com>]

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On 11/4/19 12:29 PM, Paolo Bonzini wrote:
> On 04/11/19 11:54, Andrew Jones wrote:
>>
>> diff --git a/lib/alloc.c b/lib/alloc.c
>> index ecdbbc44dbf9..ed8f5f94c9b0 100644
>> --- a/lib/alloc.c
>> +++ b/lib/alloc.c
>> @@ -46,15 +46,17 @@ void *memalign(size_t alignment, size_t size)
>>  	uintptr_t blkalign;
>>  	uintptr_t mem;
>>  
>> +	if (!size)
>> +		return NULL;
>> +
>> +	assert(alignment >= sizeof(void *) && is_power_of_2(alignment));
>>  	assert(alloc_ops && alloc_ops->memalign);
>> -	if (alignment <= sizeof(uintptr_t))
>> -		alignment = sizeof(uintptr_t);
>> -	else
>> -		size += alignment - 1;
>>  
>> +	size += alignment - 1;
>>  	blkalign = MAX(alignment, alloc_ops->align_min);
>>  	size = ALIGN(size + METADATA_EXTRA, alloc_ops->align_min);
>>  	p = alloc_ops->memalign(blkalign, size);
>> +	assert(p);

I had some more time to think about and test this and I think returning
NULL here is more useful. My usecase is a limit test where I allocate
until I get a NULL and then free everything afterwards.

>>  
>>  	/* Leave room for metadata before aligning the result.  */
>>  	mem = (uintptr_t)p + METADATA_EXTRA;
> 
> Looks good, this is what I am queuing.
> 
> Paolo





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