From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Subject: Re: [PATCH v2 06/22] ethdev: support attach or detach
 share device from secondary
Date: Thu, 21 Jun 2018 10:06:20 +0100
Message-ID: <24f21c6f-e04c-0aa6-61fe-00893aa07a49@intel.com>
References: <20180607123849.14439-1-qi.z.zhang@intel.com>
 <20180621020059.1198-1-qi.z.zhang@intel.com>
 <20180621020059.1198-7-qi.z.zhang@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: konstantin.ananyev@intel.com, dev@dpdk.org, bruce.richardson@intel.com,
 ferruh.yigit@intel.com, benjamin.h.shelton@intel.com,
 narender.vangati@intel.com
To: Qi Zhang <qi.z.zhang@intel.com>, thomas@monjalon.net
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 35D621BB47
 for <dev@dpdk.org>; Thu, 21 Jun 2018 11:06:24 +0200 (CEST)
In-Reply-To: <20180621020059.1198-7-qi.z.zhang@intel.com>
Content-Language: en-US
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On 21-Jun-18 3:00 AM, Qi Zhang wrote:
> This patch cover the multi-process hotplug case when a share device
> attach/detach request be issued from secondary process, the implementation
> references malloc_mp.c.
> 
> device attach on secondary:
> a) secondary send async request to primary and wait on a condition
>     which will be released by matched response from primary.
> b) primary receive the request and attach the new device if failed
>     goto i).
> c) primary forward attach request to all secondary as async request
>     (because this in mp thread context, use sync request will deadlock)
> d) secondary receive request and attach device and send reply.
> e) primary check the reply if all success go to j).
> f) primary send attach rollback async request to all secondary.
> g) secondary receive the request and detach device and send reply.
> h) primary receive the reply and detach device as rollback action.
> i) send fail response to secondary, goto k).
> j) send success response to secondary.
> k) secondary process receive response and return.
> 
> device detach on secondary:
> a) secondary send async request to primary and wait on a condition
>     which will be released by matched response from primary.
> b) primary receive the request and  perform pre-detach check, if device
>     is locked, goto j).
> c) primary send pre-detach async request to all secondary.
> d) secondary perform pre-detach check and send reply.
> e) primary check the reply if any fail goto j).
> f) primary send detach async request to all secondary
> g) secondary detach the device and send reply
> h) primary detach the device.
> i) send success response to secondary, goto k).
> j) send fail response to secondary.
> k) secondary process receive response and return.
> 
> Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
> ---
> 

<snip>

> -static int handle_secondary_request(const struct rte_mp_msg *msg, const void *peer)
> +static int
> +check_reply(const struct eth_dev_mp_req *req, const struct rte_mp_reply *reply)
> +{
> +	struct eth_dev_mp_req *resp;
> +	int i;
> +
> +	if (reply->nb_received != reply->nb_sent)
> +		return -EINVAL;
> +
> +	for (i = 0; i < reply->nb_received; i++) {
> +		resp = (struct eth_dev_mp_req *)reply->msgs[i].param;
> +
> +		if (resp->t != req->t) {
> +			ethdev_log(ERR, "Unexpected response to async request\n");
> +			return -EINVAL;
> +		}
> +
> +		if (resp->id != req->id) {
> +			ethdev_log(ERR, "response to wrong async request\n");
> +			return -EINVAL;
> +		}
> +
> +		if (resp->result)
> +			return resp->result;
> +	}
> +
> +	return 0;
> +}

As far as i understand, return values from this will propagate all the 
way up to user return value. How would a user differentiate between 
-EINVAL returned from invalid parameters, and -EINVAL from failed reply? 
I think this error code should be different (don't know which one though 
:) ).

(as a side note, you keep returning -EINVAL all over the place, even 
when problem is not in user's arguments - you should probably fix those 
too. for example, if request ID not found, return code should probably 
be something like -ENOENT)


-- 
Thanks,
Anatoly