Re: [Intel-wired-lan] [PATCH v2 net-next 7/9] net: netdevsim: mimic tc-taprio offload

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Jiri Pirko <jiri@resnulli.us>,
	Pedro Tammela <pctammela@mojatatu.com>,
	netdev@vger.kernel.org,
	Richard Cochran <richardcochran@gmail.com>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	linux-kernel@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
	intel-wired-lan@lists.osuosl.org,
	Maxim Georgiev <glipus@gmail.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Peilin Ye <yepeilin.cs@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Zhengchao Shao <shaozhengchao@huawei.com>,
	Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [Intel-wired-lan] [PATCH v2 net-next 7/9] net: netdevsim: mimic tc-taprio offload
Date: Tue, 01 Aug 2023 11:06:46 -0700	[thread overview]
Message-ID: <87il9y63ih.fsf@intel.com> (raw)
In-Reply-To: <20230801174347.gtmxoqybhvbbl2rg@skbuf>

Vladimir Oltean <vladimir.oltean@nxp.com> writes:

> On Tue, Aug 01, 2023 at 10:39:23AM -0700, Vinicius Costa Gomes wrote:
>> Hi Vladimir,
>> 
>> Vladimir Oltean <vladimir.oltean@nxp.com> writes:
>> 
>> > On Wed, Jun 14, 2023 at 05:06:24PM -0700, Vinicius Costa Gomes wrote:
>> >> > +static int nsim_setup_tc_taprio(struct net_device *dev,
>> >> > +				struct tc_taprio_qopt_offload *offload)
>> >> > +{
>> >> > +	int err = 0;
>> >> > +
>> >> > +	switch (offload->cmd) {
>> >> > +	case TAPRIO_CMD_REPLACE:
>> >> > +	case TAPRIO_CMD_DESTROY:
>> >> > +		break;
>> >> 
>> >> I was thinking about how useful would proper validation of the
>> >> parameters be? Thinking that we could detect "driver API" breakages
>> >> earlier, and we want it documented that the drivers should check for the
>> >> things that it supports.
>> >> 
>> >> Makes sense?
>> >
>> > Sorry, I lack imagination as to what the netdevsim driver may check for.
>> > The taprio offload parameters should always be valid, properly speaking,
>> > otherwise the Qdisc wouldn't be passing them on to the driver. At least
>> > that would be the intention. The rest are hardware specific checks for
>> > hardware specific limitations. Here there is no hardware.
>> >
>> 
>> Trying to remember what was going through my mind when I said that.
>> 
>> What I seem to recall is something that would help us "keep honest":
>> I was worrying about someone (perhaps myself ;-) sneaking a new feature
>> in taprio and forgetting to update other drivers.
>> 
>> I thought that adding a check for the existing parameters would help
>> detect those kind of things. If anything unknown was there in the
>> offload struct, netdevsim would complain loudly.
>> 
>> Perhaps I was worrying too much. And the way to solve that is to keep
>> active attention against that during review.
>
> Ok, so I'm not making any change to the patch set as a result of this
> comment, would you agree?

Agreed.

Cheers,
-- 
Vinicius
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