Re: [dpdk-dev] [PATCH 2/2] lpm: hide internal data

["Medvedkin, Vladimir" <vladimir.medvedkin@intel.com>]

Hi Ruifeng,

On 15/09/2020 17:02, Bruce Richardson wrote:
> On Mon, Sep 07, 2020 at 04:15:17PM +0800, Ruifeng Wang wrote:
>> Fields except tbl24 and tbl8 in rte_lpm structure have no
>> need to be exposed to the user.
>> Hide the unneeded exposure of structure fields for better
>> ABI maintainability.
>>
>> Suggested-by: David Marchand <david.marchand@redhat.com>
>> Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
>> Reviewed-by: Phil Yang <phil.yang@arm.com>
>> ---
>>   lib/librte_lpm/rte_lpm.c | 152 +++++++++++++++++++++++----------------
>>   lib/librte_lpm/rte_lpm.h |   7 --
>>   2 files changed, 91 insertions(+), 68 deletions(-)
>>
> <snip>
>> diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h
>> index 03da2d37e..112d96f37 100644
>> --- a/lib/librte_lpm/rte_lpm.h
>> +++ b/lib/librte_lpm/rte_lpm.h
>> @@ -132,17 +132,10 @@ struct rte_lpm_rule_info {
>>   
>>   /** @internal LPM structure. */
>>   struct rte_lpm {
>> -	/* LPM metadata. */
>> -	char name[RTE_LPM_NAMESIZE];        /**< Name of the lpm. */
>> -	uint32_t max_rules; /**< Max. balanced rules per lpm. */
>> -	uint32_t number_tbl8s; /**< Number of tbl8s. */
>> -	struct rte_lpm_rule_info rule_info[RTE_LPM_MAX_DEPTH]; /**< Rule info table. */
>> -
>>   	/* LPM Tables. */
>>   	struct rte_lpm_tbl_entry tbl24[RTE_LPM_TBL24_NUM_ENTRIES]
>>   			__rte_cache_aligned; /**< LPM tbl24 table. */
>>   	struct rte_lpm_tbl_entry *tbl8; /**< LPM tbl8 table. */
>> -	struct rte_lpm_rule *rules_tbl; /**< LPM rules. */
>>   };
>>   
> 
> Since this changes the ABI, does it not need advance notice?
> 
> [Basically the return value point from rte_lpm_create() will be different,
> and that return value could be used by rte_lpm_lookup() which as a static
> inline function will be in the binary and using the old structure offsets.]
> 

Agree with Bruce, this patch breaks ABI, so it can't be accepted without 
prior notice.

>>   /** LPM RCU QSBR configuration structure. */
>> -- 
>> 2.17.1
>>

-- 
Regards,
Vladimir