netdev - Re: [PATCH RESEND net-next v4 3/4] sfc: support unicast PTP

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Date:   Tue, 14 Mar 2023 16:55:44 +0000
From:   Edward Cree <ecree.xilinx@...il.com>
To:     Íñigo Huguet <ihuguet@...hat.com>,
        habetsm.xilinx@...il.com, richardcochran@...il.com
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        Yalin Li <yalli@...hat.com>
Subject: Re: [PATCH RESEND net-next v4 3/4] sfc: support unicast PTP

On 14/03/2023 10:09, Íñigo Huguet wrote:
> When sending a PTP event packet, add the correct filters that will make
> that future incoming unicast PTP event packets will be timestamped.
> The unicast address for the filter is gotten from the outgoing skb
> before sending it.
> 
> Until now they were not timestamped because only filters that match with
> the PTP multicast addressed were being configured into the NIC for the
> PTP special channel. Packets received through different channels are not
> timestamped, getting "received SYNC without timestamp" error in ptp4l.
> 
> Note that the inserted filters are never removed unless the NIC is stopped
> or reconfigured, so efx_ptp_stop is called. Removal of old filters will
> be handled by the next patch.
> 
> Additionally, cleanup a bit efx_ptp_xmit_skb_mc to use the reverse xmas
> tree convention and remove an unnecessary assignment to rc variable in
> void function.
> 
> Reported-by: Yalin Li <yalli@...hat.com>
> Signed-off-by: Íñigo Huguet <ihuguet@...hat.com>

Few nits below, but still
Acked-by: Edward Cree <ecree.xilinx@...il.com>

> +static bool efx_ptp_filter_exists(struct list_head *ptp_list,
> +				  struct efx_filter_spec *spec)
> +{
> +	struct efx_ptp_rxfilter *rxfilter;
> +
> +	list_for_each_entry(rxfilter, ptp_list, list) {
> +		if (rxfilter->ether_type == spec->ether_type &&
> +		    rxfilter->loc_port == spec->loc_port &&
> +		    !memcmp(rxfilter->loc_host, spec->loc_host, sizeof(spec->loc_host)))
> +			return true;
> +	}
> +
> +	return false;
> +}

Technically this could be more efficient if we used an rhashtable
 instead of a list, but I guess we don't expect the list to grow
 very long.

> +static int efx_ptp_insert_unicast_filter(struct efx_nic *efx,
> +					 struct sk_buff *skb)
> +{
> +	struct efx_ptp_data *ptp = efx->ptp_data;
> +	int rc;
> +
> +	if (!efx_ptp_valid_unicast_event_pkt(skb))
> +		return -EINVAL;
> +
> +	if (skb->protocol == htons(ETH_P_IP)) {
> +		__be32 addr = ip_hdr(skb)->saddr;
> +
> +		rc = efx_ptp_insert_ipv4_filter(efx, &ptp->rxfilters_ucast,
> +						addr, PTP_EVENT_PORT);
> +		if (rc < 0)
> +			goto fail;
> +
> +		rc = efx_ptp_insert_ipv4_filter(efx, &ptp->rxfilters_ucast,
> +						addr, PTP_GENERAL_PORT);
> +		if (rc < 0)
> +			goto fail;
> +	} else if (efx_ptp_use_mac_tx_timestamps(efx)) {
> +		/* IPv6 PTP only supported by devices with MAC hw timestamp */
> +		struct in6_addr *addr = &ipv6_hdr(skb)->saddr;
> +
> +		rc = efx_ptp_insert_ipv6_filter(efx, &ptp->rxfilters_ucast,
> +						addr, PTP_EVENT_PORT);
> +		if (rc < 0)
> +			goto fail;
> +
> +		rc = efx_ptp_insert_ipv6_filter(efx, &ptp->rxfilters_ucast,
> +						addr, PTP_GENERAL_PORT);
> +		if (rc < 0)
> +			goto fail;
> +	} else {
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +
> +fail:
> +	efx_ptp_remove_filters(efx, &ptp->rxfilters_ucast);
> +	return rc;
> +}

Why does failing to insert one filter mean we need to remove *all*
 the unicast filters we have?  (I'm not even sure it's necessary
 to remove the new EVENT filter if the GENERAL filter fails.)