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To: Thomas Monjalon <thomas@monjalon.net>
Cc: "Min Hu (Connor)" <humin29@huawei.com>, dev@dpdk.org,
 ferruh.yigit@intel.com
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 <2252218.jVnlyW2HoW@thomas>
From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Organization: OKTET Labs
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Date: Thu, 15 Apr 2021 15:03:58 +0300
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Subject: Re: [dpdk-dev] [PATCH v4] ethdev: add sanity checks in control APIs
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On 4/15/21 2:57 PM, Thomas Monjalon wrote:
> 15/04/2021 10:15, Andrew Rybchenko:
>>>  	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_configure, -ENOTSUP);
>> In theory, the first argument is sufficient to make the ops
>> check, but I think it is the right solution to keep it as is
>> since current tendency is to check operation support when
>> driver callback is really required and we're going to use it.
>> However, if we do it just after port_id check, we'll have a
>> way to check for callback support without any side effects
>> if we provide invalid argument value. I.e. if -ENOTSUP is
>> returned, callback is not supported, if -EINVAL, callback is
>> supported (but argument is invalid and nothing done).
>> However, it looks a bit fragile and not always possible.
>> Thoughts on it are welcome.
> Sorry I don't understand it fully.
> You say we should check for ENOTSUP at the very beginning?

I'm just trying to consider it and understand if it would be
right or wrong.