Re: [PATCH net-next v17 13/14] net: ethtool: Add support for tsconfig command to get/set hwtstamp config

[Kory Maincent]

Hello Jakub, 

On Mon, 15 Jul 2024 07:59:26 -0700
Jakub Kicinski <kuba@xxxxxxxxxx> wrote:

Thanks for the review and sorry for the late reply.

> On Tue, 09 Jul 2024 15:53:45 +0200 Kory Maincent wrote:
> > +	/* Get the hwtstamp config from netlink */
> > +	if (tb[ETHTOOL_A_TSCONFIG_TX_TYPES]) {
> > +		ret = ethnl_parse_bitset(&req_tx_type, &mask,
> > +					 __HWTSTAMP_TX_CNT,
> > +					 tb[ETHTOOL_A_TSCONFIG_TX_TYPES],
> > +					 ts_tx_type_names, info->extack);
> > +		if (ret < 0)
> > +			goto err_clock_put;
> > +
> > +		/* Select only one tx type at a time */
> > +		if (ffs(req_tx_type) != fls(req_tx_type)) {
> > +			ret = -EINVAL;
> > +			goto err_clock_put;
> > +		}
> > +
> > +		hwtst_config.tx_type = ffs(req_tx_type) - 1;
> > +	}
> > +	if (tb[ETHTOOL_A_TSCONFIG_RX_FILTERS]) {
> > +		ret = ethnl_parse_bitset(&req_rx_filter, &mask,
> > +					 __HWTSTAMP_FILTER_CNT,
> > +					 tb[ETHTOOL_A_TSCONFIG_RX_FILTERS],
> > +					 ts_rx_filter_names, info->extack);
> > +		if (ret < 0)
> > +			goto err_clock_put;
> > +
> > +		/* Select only one rx filter at a time */
> > +		if (ffs(req_rx_filter) != fls(req_rx_filter)) {
> > +			ret = -EINVAL;
> > +			goto err_clock_put;
> > +		}
> > +
> > +		hwtst_config.rx_filter = ffs(req_rx_filter) - 1;
> > +	}
> > +	if (tb[ETHTOOL_A_TSCONFIG_HWTSTAMP_FLAGS]) {
> > +		ret = nla_get_u32(tb[ETHTOOL_A_TSCONFIG_HWTSTAMP_FLAGS]);
> > +		if (ret < 0)
> > +			goto err_clock_put;
> > +		hwtst_config.flags = ret;
> > +	}  
> 
> We should be tracking mod on these, too. Separately from the provider
> mod bit, let's not call the driver and send notification if nothing
> changed.

Ok
 
> > +	ret = net_hwtstamp_validate(&hwtst_config);
> > +	if (ret)
> > +		goto err_clock_put;
> > +
> > +	/* Disable current time stamping if we try to enable another one */
> > +	if (mod && (hwtst_config.tx_type || hwtst_config.rx_filter)) {
> > +		struct kernel_hwtstamp_config zero_config = {0};
> > +
> > +		ret = dev_set_hwtstamp_phylib(dev, &zero_config,
> > info->extack);
> > +		if (ret < 0)
> > +			goto err_clock_put;
> > +	}
> > +
> > +	/* Changed the selected hwtstamp source if needed */
> > +	if (mod) {
> > +		struct hwtstamp_provider *__hwtstamp;
> > +
> > +		__hwtstamp = rcu_replace_pointer_rtnl(dev->hwtstamp,
> > hwtstamp);
> > +		if (__hwtstamp)
> > +			call_rcu(&__hwtstamp->rcu_head,
> > +				 remove_hwtstamp_provider);
> > +	}
> > +
> > +	ret = dev_set_hwtstamp_phylib(dev, &hwtst_config, info->extack);
> > +	if (ret < 0)
> > +		return ret;  
> 
> We can't unwind to old state here?

Yes indeed we could unwind old state here. I will update it in next version.

> Driver can change hwtst_config right? "upgrade" the rx_filter 
> to a broader one, IIRC. Shouldn't we reply to the set command with 
> the resulting configuration, in case it changed? Basically provide 
> the same info as the notification would.

Yes, the driver does that.
Indeed that's a good idea to report the resulting configuration.
I will take a look at how I can do that.

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com