Re: [dpdk-dev] [PATCH] mempool: fix local cache initialization

[Olivier Matz <olivier.matz@6wind.com>]

Hi Sergio,

On 06/09/2016 09:57 AM, Sergio Gonzalez Monroy wrote:
> Hi Olivier,
> 
> On 08/06/2016 20:14, Olivier Matz wrote:
>> Hi Sergio,
>>
>> Good catch, thanks. The patch looks ok, just few comments
>> on the commit log:
>>
>> On 06/08/2016 05:10 PM, Sergio Gonzalez Monroy wrote:
>>> The mempool local cache is not being initialize properly leading to
>> 'initialize' -> 'initialized' ?
>> and maybe 'is not being' -> 'was not' ?
>>
>>> undefined behavior in cases where the allocated memory was used and left
>>> with data.
>>>
>>> Fixes: af75078fece3 ("first public release")
>> I think it fixes this one instead:
>>
>> 213af31e0960 ("mempool: reduce structure size if no cache needed")
> 
> Fair enough, I thought the issue was there as we never
> initialized/zeroed the local cache
> on mempool creation. Usually we would have allocated all mempools on
> init (or close)
> and that would be it (initially all memory would be zeroed), but I think
> you could still
> manage to reproduce the problem if somehow you where to do something like:
> rte_malloc(), rte_free(), rte_mempool_create() and the memory was the
> one we got
> with malloc and never gets zeroed again.

Before Keith's commit (213af31e0960), the local cache was initialized
when doing the memset() because it was included in the mempool
structure. So I think the problem did not exist before this patch.
Or did I miss something in your explanation?

Regards,
Olivier