From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
Subject: Re: [PATCH v2 01/12] ethdev: add API to query packet
 type filling info
Date: Thu, 25 Feb 2016 22:57:04 +0800
Message-ID: <56CF1640.1060005@intel.com>
References: <1451544799-70776-1-git-send-email-jianfeng.tan@intel.com>
 <1452836759-63540-1-git-send-email-jianfeng.tan@intel.com>
 <1452836759-63540-2-git-send-email-jianfeng.tan@intel.com>
 <2601191342CEEE43887BDE71AB97725836AE6184@irsmsx105.ger.corp.intel.com>
 <56CEA4DE.8040702@intel.com>
 <2601191342CEEE43887BDE71AB97725836B0B2D4@irsmsx105.ger.corp.intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
 "dev@dpdk.org" <dev@dpdk.org>
Return-path: <dev-bounces@dpdk.org>
Received: from mga03.intel.com (mga03.intel.com [134.134.136.65])
 by dpdk.org (Postfix) with ESMTP id 2A82A2BD7
 for <dev@dpdk.org>; Thu, 25 Feb 2016 15:57:07 +0100 (CET)
In-Reply-To: <2601191342CEEE43887BDE71AB97725836B0B2D4@irsmsx105.ger.corp.intel.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>



On 2/25/2016 7:17 PM, Ananyev, Konstantin wrote:
>>>> +int
>>>> +rte_eth_dev_get_ptype_info(uint8_t port_id, uint32_t ptype_mask,
>>>> +			   uint32_t ptypes[], int num)
>>>> +{
>>>> +	int ret, i, j;
>>>> +	struct rte_eth_dev *dev;
>>>> +	uint32_t all_ptypes[RTE_PTYPE_MAX_NUM];
>>>> +
>>>> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>>>> +	dev = &rte_eth_devices[port_id];
>>>> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_ptype_info_get, -ENOTSUP);
>>>> +	ret = (*dev->dev_ops->dev_ptype_info_get)(dev, all_ptypes);
>>>> +
>>>> +	for (i = 0, j = 0; i < ret && j < num; ++i)
>>>> +		if (all_ptypes[i] & ptype_mask)
>>>> +			ptypes[j++] = all_ptypes[i];
>>>> +
>>>> +	return ret;
>>> I think it needs to be something like:
>>>
>>> j = 0;
>>> for (i = 0, j = 0; i < ret; ++i) {
>>>        if (all_ptypes[i] & ptype_mask) {
>>>             if (j < num)
>>>                  ptypes[j] = all_ptypes[i];
>>>             j++;
>>>      }
>>> }
>>>
>>> return j;
>>>
>>> Konstantin
>>>
>> You are right, my previous code is wrong.
>> But I have a concern about your code above: under the condition that the
>> caller does not provide big enough array to store adequate ptypes, it
>> has no way to return the not-enough-memory message back to caller.
>>
>> So under that condition, how about we just return -ENOMEM?
>>
> As I remember, the agreement was - we don't return an -ENOMEM in that case.
> What we do return - number of entries in ptypes[] that would be required to
> store all adequate ptypes (similar to what snprinf() does).
> So the user can do something like that (if he needs to):
>
> num = rte_eth_dev_get_ptype_info(port,  ptype_mask, NULL, 0);
> if (num < 0) {/*error handling*/}
> ptypes = alloca(num * ptypes[0]);
> n = rte_eth_dev_get_ptype_info(port,  ptype_mask, ptypes, num);
> ...
>
> Konstantin
>

Oh, yes. Sorry, I previously misunderstood your code.

But I still have a concern of above way that this APIs should be called 
two times. I suggest to use a way, like strdup, callee to malloc, caller 
to free. I send out v3 right now, please have a look at if it's OK.

Thanks,
Jianfeng