Re: [dpdk-dev] [PATCH] ethdev: fix DMA zone reserve not honoring size

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 01-Apr-19 8:30 AM, Andrew Rybchenko wrote:
> On 3/31/19 7:25 PM, Pavan Nikhilesh Bhagavatula wrote:
>> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
>>
>> The `rte_eth_dma_zone_reserve()` is generally used to create HW rings.
>> In some scenarios when a driver needs to reconfigure the ring size
>> since the named memzone already exists it returns the previous memzone
>> without checking if a different sized ring is requested.
>>
>> Introduce a check to see if the ring size requested is different from the
>> previously created memzone length.
>>
>> Fixes: 719dbebceb81 ("xen: allow determining DOM0 at runtime")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
>> ---
>>   lib/librte_ethdev/rte_ethdev.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/librte_ethdev/rte_ethdev.c 
>> b/lib/librte_ethdev/rte_ethdev.c
>> index 12b66b68c..4ae12e43b 100644
>> --- a/lib/librte_ethdev/rte_ethdev.c
>> +++ b/lib/librte_ethdev/rte_ethdev.c
>> @@ -3604,9 +3604,12 @@ rte_eth_dma_zone_reserve(const struct 
>> rte_eth_dev *dev, const char *ring_name,
>>       }
>>       mz = rte_memzone_lookup(z_name);
>> -    if (mz)
>> +    if (mz && (mz->len == size))
>>           return mz;
>> +    if (mz)
>> +        rte_memzone_free(mz);
> 
> NACK
> I really don't like that API which should reserve does free if requested
> size does not match previously allocated.
> I understand the motivation, but I don't think the solution is correct.

Why does size change in the first place?

> 
>> +
>>       return rte_memzone_reserve_aligned(z_name, size, socket_id,
>>               RTE_MEMZONE_IOVA_CONTIG, align);
>>   }
> 
> 


-- 
Thanks,
Anatoly