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From: Kevin Traynor <ktraynor@redhat.com>
To: Ruifeng Wang <Ruifeng.Wang@arm.com>,
	"Medvedkin, Vladimir" <vladimir.medvedkin@intel.com>,
	Bruce Richardson <bruce.richardson@intel.com>,
	Michel Machado <michel@digirati.com.br>,
	Cody Doucette <doucette@bu.edu>,
	Andre Nathan <andre@digirati.com.br>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH 2/2] lpm: hide internal data
Date: Tue, 13 Oct 2020 14:53:16 +0100
Message-ID: <48834549-00e9-b762-4915-9a2dd0e5fe1d@redhat.com> (raw)
In-Reply-To: <VI1PR0802MB2351A9EBC402388F3C977FC29E080@VI1PR0802MB2351.eurprd08.prod.outlook.com>

Hi Gatekeeper maintainers (I think),

fyi - there is a proposal to remove some members of a struct in DPDK LPM
API that Gatekeeper is using [1]. It would be only from DPDK 20.11 but
as it's an LTS I guess it would probably hit Debian in a few months.

The full thread is here:
http://inbox.dpdk.org/dev/20200907081518.46350-1-ruifeng.wang@arm.com/

Maybe you can take a look and tell us if they are needed in Gatekeeper
or you can workaround it?

thanks,
Kevin.

[1]
https://github.com/AltraMayor/gatekeeper/blob/master/gt/lua_lpm.c#L235-L248

On 09/10/2020 07:54, Ruifeng Wang wrote:
> 
>> -----Original Message-----
>> From: Kevin Traynor <ktraynor@redhat.com>
>> Sent: Wednesday, September 30, 2020 4:46 PM
>> To: Ruifeng Wang <Ruifeng.Wang@arm.com>; Medvedkin, Vladimir
>> <vladimir.medvedkin@intel.com>; Bruce Richardson
>> <bruce.richardson@intel.com>
>> Cc: dev@dpdk.org; Honnappa Nagarahalli
>> <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
>> Subject: Re: [dpdk-dev] [PATCH 2/2] lpm: hide internal data
>>
>> On 16/09/2020 04:17, Ruifeng Wang wrote:
>>>
>>>> -----Original Message-----
>>>> From: Medvedkin, Vladimir <vladimir.medvedkin@intel.com>
>>>> Sent: Wednesday, September 16, 2020 12:28 AM
>>>> To: Bruce Richardson <bruce.richardson@intel.com>; Ruifeng Wang
>>>> <Ruifeng.Wang@arm.com>
>>>> Cc: dev@dpdk.org; Honnappa Nagarahalli
>>>> <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
>>>> Subject: Re: [PATCH 2/2] lpm: hide internal data
>>>>
>>>> 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.
>>>>
>>> So if the change wants to happen in 20.11, a deprecation notice should
>>> have been added in 20.08.
>>> I should have added a deprecation notice. This change will have to wait for
>> next ABI update window.
>>>
>>
>> Do you plan to extend? or is this just speculative?
> It is speculative.
> 
>>
>> A quick scan and there seems to be several projects using some of these
>> members that you are proposing to hide. e.g. BESS, NFF-Go, DPVS,
>> gatekeeper. I didn't look at the details to see if they are really needed.
>>
>> Not sure how much notice they'd need or if they update DPDK much, but I
>> think it's worth having a closer look as to how they use lpm and what the
>> impact to them is.
> Checked the projects listed above. BESS, NFF-Go and DPVS don't access the members to be hided.
> They will not be impacted by this patch.
> But Gatekeeper accesses the rte_lpm internal members that to be hided. Its compilation will be broken with this patch.
> 
>>
>>> Thanks.
>>> Ruifeng
>>>>>>   /** LPM RCU QSBR configuration structure. */
>>>>>> --
>>>>>> 2.17.1
>>>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Vladimir
> 


  reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-07  8:15 [dpdk-dev] [PATCH 0/2] LPM changes Ruifeng Wang
2020-09-07  8:15 ` [dpdk-dev] [PATCH 1/2] lpm: fix free of data structure Ruifeng Wang
2020-09-15 15:55   ` Bruce Richardson
2020-09-15 16:25   ` Medvedkin, Vladimir
2020-09-07  8:15 ` [dpdk-dev] [PATCH 2/2] lpm: hide internal data Ruifeng Wang
2020-09-15 16:02   ` Bruce Richardson
2020-09-15 16:28     ` Medvedkin, Vladimir
2020-09-16  3:17       ` Ruifeng Wang
2020-09-30  8:45         ` Kevin Traynor
2020-10-09  6:54           ` Ruifeng Wang
2020-10-13 13:53             ` Kevin Traynor [this message]
2020-10-13 14:58               ` Michel Machado
2020-10-13 15:41                 ` Medvedkin, Vladimir
2020-10-13 17:46                   ` Michel Machado
2020-10-13 19:06                     ` Medvedkin, Vladimir
2020-10-13 19:48                       ` Michel Machado
2020-10-14 13:10                         ` Medvedkin, Vladimir
2020-10-14 23:57                           ` Honnappa Nagarahalli
2020-10-15 13:39                             ` Michel Machado
2020-10-15 17:38                               ` Honnappa Nagarahalli
2020-10-15 19:30                                 ` Medvedkin, Vladimir
2020-10-15 22:54                                   ` Honnappa Nagarahalli
2020-10-16 11:39                                     ` Kevin Traynor
2020-10-16 13:55                                       ` Michel Machado
2020-10-19 14:53                                     ` David Marchand
2020-10-20 14:22                                       ` Thomas Monjalon
2020-10-20 14:32                                         ` Medvedkin, Vladimir
2020-10-19 17:53             ` Honnappa Nagarahalli
2020-09-15 14:41 ` [dpdk-dev] [PATCH 0/2] LPM changes David Marchand
2020-10-19 13:37   ` Kevin Traynor
2020-10-21  3:02 ` [dpdk-dev] [PATCH v2 " Ruifeng Wang
2020-10-21  3:02   ` [dpdk-dev] [PATCH v2 1/2] lpm: fix free of data structure Ruifeng Wang
2020-10-21  3:02   ` [dpdk-dev] [PATCH v2 2/2] lpm: hide internal data Ruifeng Wang
2020-10-21  7:58     ` Thomas Monjalon
2020-10-21  8:15       ` Ruifeng Wang
2020-10-22 15:14     ` David Marchand
2020-10-23  6:13       ` Ruifeng Wang
2020-10-23 16:08         ` Medvedkin, Vladimir
2020-10-23  9:38 ` [dpdk-dev] [PATCH v3 0/2] LPM changes David Marchand
2020-10-23  9:38   ` [dpdk-dev] [PATCH v3 1/2] lpm: fix free of data structure David Marchand
2020-10-23  9:38   ` [dpdk-dev] [PATCH v3 2/2] lpm: hide internal data David Marchand
2020-10-26  8:26   ` [dpdk-dev] [PATCH v3 0/2] LPM changes David Marchand

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