Re: [PATCH net-next v11 12/13] net: ethtool: tsinfo: Add support for hwtstamp provider and get/set hwtstamp config

[Simon Horman <horms@kernel.org>]

On Mon, Apr 22, 2024 at 02:50:27PM +0200, Kory Maincent wrote:
> Enhance 'get' command to retrieve tsinfo of hwtstamp providers within a
> network topology and read current hwtstamp configuration.
> 
> Introduce support for ETHTOOL_MSG_TSINFO_SET ethtool netlink socket to
> configure hwtstamp of a PHC provider. Note that simultaneous hwtstamp
> isn't supported; configuring a new one disables the previous setting.
> 
> Also, add support for a specific dump command to retrieve all hwtstamp
> providers within the network topology, with added functionality for
> filtered dump to target a single interface.
> 
> Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>

Hi Kory,

Some minor feedback from my side.

> diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
> index 23b43f59fcfb..f901394507b3 100644
> --- a/include/linux/ptp_clock_kernel.h
> +++ b/include/linux/ptp_clock_kernel.h
> @@ -426,6 +426,43 @@ struct ptp_clock *ptp_clock_get_by_index(struct device *dev, int index);
>  
>  void ptp_clock_put(struct device *dev, struct ptp_clock *ptp);
>  
> +/**
> + * netdev_ptp_clock_find() - obtain the next PTP clock in the netdev
> + *			     topology
> + *
> + * @dev:    Pointer of the net device
> + * @indexp:  Pointer of ptp clock index start point
> + */

Recently -Wall was added to the kernel CI ./scripts/kernel-doc -none
test, which means that Kernel docs are now expected to
document return values. It would be nice to add them for new
code.

> +
> +struct ptp_clock *netdev_ptp_clock_find(struct net_device *dev,
> +					unsigned long *indexp);

...

> diff --git a/net/ethtool/tsinfo.c b/net/ethtool/tsinfo.c

...

> -const struct nla_policy ethnl_tsinfo_get_policy[] = {
> +const struct nla_policy
> +ethnl_tsinfo_hwtstamp_provider_policy[ETHTOOL_A_TSINFO_HWTSTAMP_PROVIDER_MAX + 1] = {

ethnl_tsinfo_hwtstamp_provider_policy seems to only be used in this file,
so it should be static.

> +	[ETHTOOL_A_TSINFO_HWTSTAMP_PROVIDER_INDEX] =
> +		NLA_POLICY_MIN(NLA_S32, 0),
> +	[ETHTOOL_A_TSINFO_HWTSTAMP_PROVIDER_QUALIFIER] =
> +		NLA_POLICY_MAX(NLA_U32, HWTSTAMP_PROVIDER_QUALIFIER_CNT - 1)
> +};
> +
> +const struct nla_policy ethnl_tsinfo_get_policy[ETHTOOL_A_TSINFO_MAX + 1] = {
>  	[ETHTOOL_A_TSINFO_HEADER]		=
>  		NLA_POLICY_NESTED(ethnl_header_policy_stats),
> +	[ETHTOOL_A_TSINFO_GHWTSTAMP] =
> +		NLA_POLICY_MAX(NLA_U8, 1),
> +	[ETHTOOL_A_TSINFO_HWTSTAMP_PROVIDER_NEST] =
> +		NLA_POLICY_NESTED(ethnl_tsinfo_hwtstamp_provider_policy),
>  };

...

> +static int ethnl_tsinfo_dump_one_ptp(struct sk_buff *skb, struct net_device *dev,
> +				     struct netlink_callback *cb,
> +				     struct ptp_clock *ptp)
> +{
> +	struct ethnl_tsinfo_dump_ctx *ctx = (void *)cb->ctx;
> +	struct tsinfo_reply_data *reply_data;
> +	struct tsinfo_req_info *req_info;
> +	void *ehdr;
> +	int ret;
> +
> +	reply_data = ctx->reply_data;
> +	req_info = ctx->req_info;
> +	req_info->hwtst.index = ptp_clock_index(ptp);
> +
> +	for (; ctx->pos_phcqualifier < HWTSTAMP_PROVIDER_QUALIFIER_CNT;
> +	     ctx->pos_phcqualifier++) {
> +		if (!netdev_support_hwtstamp_qualifier(dev,
> +						       ctx->pos_phcqualifier))
> +			continue;
> +
> +		ehdr = ethnl_dump_put(skb, cb,
> +				      ETHTOOL_MSG_TSINFO_GET_REPLY);
> +		if (!ehdr)
> +			return -EMSGSIZE;
> +
> +		memset(reply_data, 0, sizeof(*reply_data));
> +		reply_data->base.dev = dev;
> +		req_info->hwtst.qualifier = ctx->pos_phcqualifier;
> +		ret = tsinfo_prepare_data(&req_info->base,
> +					  &reply_data->base,
> +					  genl_info_dump(cb));
> +		if (ret < 0)
> +			break;
> +
> +		ret = ethnl_fill_reply_header(skb, dev,
> +					      ETHTOOL_A_TSINFO_HEADER);
> +		if (ret < 0)
> +			break;
> +
> +		ret = tsinfo_fill_reply(skb, &req_info->base,
> +					&reply_data->base);
> +		if (ret < 0)
> +			break;
> +	}
> +
> +	reply_data->base.dev = NULL;
> +	if (ret < 0)
> +		genlmsg_cancel(skb, ehdr);
> +	else
> +		genlmsg_end(skb, ehdr);

I suppose it can't occur, but if the for loop iterates zero times,
then ret and ehdr will be uninitialised here.

Flagged by Smatch.

> +	return ret;
> +}

...