netdev - Re: [PATCH v5 net-next 2/8] sfc: add devlink info support for ef100

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Date:   Tue, 7 Feb 2023 15:10:51 +0000
From:   "Lucero Palau, Alejandro" <alejandro.lucero-palau@....com>
To:     Jiri Pirko <jiri@...nulli.us>,
        "Lucero Palau, Alejandro" <alejandro.lucero-palau@....com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-net-drivers (AMD-Xilinx)" <linux-net-drivers@....com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "habetsm.xilinx@...il.com" <habetsm.xilinx@...il.com>,
        "ecree.xilinx@...il.com" <ecree.xilinx@...il.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "corbet@....net" <corbet@....net>,
        "jiri@...dia.com" <jiri@...dia.com>
Subject: Re: [PATCH v5 net-next 2/8] sfc: add devlink info support for ef100


On 2/7/23 14:58, Jiri Pirko wrote:
> Tue, Feb 07, 2023 at 03:42:45PM CET, alejandro.lucero-palau@....com wrote:
>> On 2/2/23 11:58, Jiri Pirko wrote:
>>> Thu, Feb 02, 2023 at 12:14:17PM CET, alejandro.lucero-palau@....com wrote:
>>>> From: Alejandro Lucero <alejandro.lucero-palau@....com>
>>>>
>>>> Support for devlink info command.
>>> You are quite brief for couple hundred line patch. Care to shed some
>>> more details for the reader? Also, use imperative mood (applies to the
>>> rest of the pathes)
>>>
>>> [...]
>>>
>> OK. I'll be more talkative and imperative here.
>>
>>>> +static int efx_devlink_info_get(struct devlink *devlink,
>>>> +				struct devlink_info_req *req,
>>>> +				struct netlink_ext_ack *extack)
>>>> +{
>>>> +	struct efx_devlink *devlink_private = devlink_priv(devlink);
>>>> +	struct efx_nic *efx = devlink_private->efx;
>>>> +	char msg[NETLINK_MAX_FMTMSG_LEN];
>>>> +	int errors_reported = 0;
>>>> +	int rc;
>>>> +
>>>> +	/* Several different MCDI commands are used. We report first error
>>>> +	 * through extack along with total number of errors. Specific error
>>>> +	 * information via system messages.
>>>> +	 */
>>>> +	rc = efx_devlink_info_board_cfg(efx, req);
>>>> +	if (rc) {
>>>> +		sprintf(msg, "Getting board info failed");
>>>> +		errors_reported++;
>>>> +	}
>>>> +	rc = efx_devlink_info_stored_versions(efx, req);
>>>> +	if (rc) {
>>>> +		if (!errors_reported)
>>>> +			sprintf(msg, "Getting stored versions failed");
>>>> +		errors_reported += rc;
>>>> +	}
>>>> +	rc = efx_devlink_info_running_versions(efx, req);
>>>> +	if (rc) {
>>>> +		if (!errors_reported)
>>>> +			sprintf(msg, "Getting board info failed");
>>>> +		errors_reported++;
>>> Under which circumstances any of the errors above happen? Is it a common
>>> thing? Or is it result of some fatal event?
>> They are not common at all. If any of those happen, it is a bad sign,
>> and it is more than likely there are more than one because something is
>> not working properly. That is the reason I only report first error found
>> plus the total number of errors detected.
>>
>>
>>> You treat it like it is quite common, which seems very odd to me.
>>> If they are rare, just return error right away to the caller.
>> Well, that is done now. And as I say, I'm not reporting all but just the
>> first one, mainly because the buffer limitation with NETLINK_MAX_FMTMSG_LEN.
>>
>> If errors trigger, a more complete information will appear in system
>> messages, so that is the reason with:
>>
>> +               NL_SET_ERR_MSG_FMT(extack,
>> +                                  "%s. %d total errors. Check system messages",
>> +                                  msg, errors_reported);
>>
>> I guess you are concerned with the extack report being overwhelmed, but
>> I do not think that is the case.
> No, I'm wondering why you just don't put error message into exack and
> return -ESOMEERROR right away.

Well, I thought the idea was to give more information to user space 
about the problem.

Previous patchsets were not reporting any error nor error information 
through extack. Now we have both.

>>>
>>>> +	}
>>>> +
>>>> +	if (errors_reported)
>>>> +		NL_SET_ERR_MSG_FMT(extack,
>>>> +				   "%s. %d total errors. Check system messages",
>>>> +				   msg, errors_reported);
>>>> +	return 0;
>>>> +}
>>>> +
>>>> static const struct devlink_ops sfc_devlink_ops = {
>>>> +	.info_get			= efx_devlink_info_get,
>>>> };
>>> [...]