Subject: Re: [RFC bpf-next 02/23] ice: make RX HW timestamp reading code more reusable

From: Maciej Fijalkowski <[email-masked]>
Date: Mon, 4 Sep 2023 16:56:32 +0200

On Thu, Aug 24, 2023 at 09:26:41PM +0200, Larysa Zaremba wrote:
> Previously, we only needed RX HW timestamp in skb path,
> hence all related code was written with skb in mind.
> But with the addition of XDP hints via kfuncs to the ice driver,
> the same logic will be needed in .xmo_() callbacks.
> 
> Put generic process of reading RX HW timestamp from a descriptor
> into a separate function.
> Move skb-related code into another source file.
> 
> Signed-off-by: Larysa Zaremba <[email-masked]>
> ---
>  drivers/net/ethernet/intel/ice/ice_ptp.c      | 24 ++++++------------
>  drivers/net/ethernet/intel/ice/ice_ptp.h      | 15 ++++++-----
>  drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 25 ++++++++++++++++++-
>  3 files changed, 41 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
> index 81d96a40d5a7..a31333972c68 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ptp.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
> @@ -2147,30 +2147,24 @@ int ice_ptp_set_ts_config(struct ice_pf *pf, struct ifreq *ifr)
>  }
>  
>  /**
> - * ice_ptp_rx_hwtstamp - Check for an Rx timestamp
> - * @rx_ring: Ring to get the VSI info
> + * ice_ptp_get_rx_hwts - Get packet Rx timestamp
>   * @rx_desc: Receive descriptor
> - * @skb: Particular skb to send timestamp with
> + * @cached_time: Cached PHC time
>   *
>   * The driver receives a notification in the receive descriptor with timestamp.
> - * The timestamp is in ns, so we must convert the result first.
>   */
> -void
> -ice_ptp_rx_hwtstamp(struct ice_rx_ring *rx_ring,
> -		    union ice_32b_rx_flex_desc *rx_desc, struct sk_buff *skb)
> +u64 ice_ptp_get_rx_hwts(const union ice_32b_rx_flex_desc *rx_desc,
> +			u64 cached_time)
>  {
> -	struct skb_shared_hwtstamps *hwtstamps;
> -	u64 ts_ns, cached_time;
>  	u32 ts_high;
> +	u64 ts_ns;
>  
>  	if (!(rx_desc->wb.time_stamp_low & ICE_PTP_TS_VALID))
> -		return;
> -
> -	cached_time = READ_ONCE(rx_ring->cached_phctime);
> +		return 0;
>  
>  	/* Do not report a timestamp if we don't have a cached PHC time */
>  	if (!cached_time)
> -		return;
> +		return 0;
>  
>  	/* Use ice_ptp_extend_32b_ts directly, using the ring-specific cached
>  	 * PHC value, rather than accessing the PF. This also allows us to
> @@ -2181,9 +2175,7 @@ ice_ptp_rx_hwtstamp(struct ice_rx_ring *rx_ring,
>  	ts_high = le32_to_cpu(rx_desc->wb.flex_ts.ts_high);
>  	ts_ns = ice_ptp_extend_32b_ts(cached_time, ts_high);
>  
> -	hwtstamps = skb_hwtstamps(skb);
> -	memset(hwtstamps, 0, sizeof(*hwtstamps));
> -	hwtstamps->hwtstamp = ns_to_ktime(ts_ns);
> +	return ts_ns;
>  }
>  
>  /**
> diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.h b/drivers/net/ethernet/intel/ice/ice_ptp.h
> index 995a57019ba7..523eefbfdf95 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ptp.h
> +++ b/drivers/net/ethernet/intel/ice/ice_ptp.h
> @@ -268,9 +268,8 @@ void ice_ptp_extts_event(struct ice_pf *pf);
>  s8 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb);
>  enum ice_tx_tstamp_work ice_ptp_process_ts(struct ice_pf *pf);
>  
> -void
> -ice_ptp_rx_hwtstamp(struct ice_rx_ring *rx_ring,
> -		    union ice_32b_rx_flex_desc *rx_desc, struct sk_buff *skb);
> +u64 ice_ptp_get_rx_hwts(const union ice_32b_rx_flex_desc *rx_desc,
> +			u64 cached_time);
>  void ice_ptp_reset(struct ice_pf *pf);
>  void ice_ptp_prepare_for_reset(struct ice_pf *pf);
>  void ice_ptp_init(struct ice_pf *pf);
> @@ -304,9 +303,13 @@ static inline bool ice_ptp_process_ts(struct ice_pf *pf)
>  {
>  	return true;
>  }
> -static inline void
> -ice_ptp_rx_hwtstamp(struct ice_rx_ring *rx_ring,
> -		    union ice_32b_rx_flex_desc *rx_desc, struct sk_buff *skb) { }
> +
> +static inline u64
> +ice_ptp_get_rx_hwts(const union ice_32b_rx_flex_desc *rx_desc, u64 cached_time)
> +{
> +	return 0;
> +}
> +
>  static inline void ice_ptp_reset(struct ice_pf *pf) { }
>  static inline void ice_ptp_prepare_for_reset(struct ice_pf *pf) { }
>  static inline void ice_ptp_init(struct ice_pf *pf) { }
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> index 8f7f6d78f7bf..b2f241b73934 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> @@ -185,6 +185,29 @@ ice_rx_csum(struct ice_rx_ring *ring, struct sk_buff *skb,
>  	ring->vsi->back->hw_csum_rx_error++;
>  }
>  
> +/**
> + * ice_ptp_rx_hwts_to_skb - Put RX timestamp into skb
> + * @rx_ring: Ring to get the VSI info
> + * @rx_desc: Receive descriptor
> + * @skb: Particular skb to send timestamp with
> + *
> + * The timestamp is in ns, so we must convert the result first.
> + */
> +static void
> +ice_ptp_rx_hwts_to_skb(struct ice_rx_ring *rx_ring,
> +		       const union ice_32b_rx_flex_desc *rx_desc,
> +		       struct sk_buff *skb)
> +{
> +	u64 ts_ns, cached_time;
> +
> +	cached_time = READ_ONCE(rx_ring->cached_phctime);

any reason for not reading cached_phctime within ice_ptp_get_rx_hwts?

> +	ts_ns = ice_ptp_get_rx_hwts(rx_desc, cached_time);
> +
> +	*skb_hwtstamps(skb) = (struct skb_shared_hwtstamps){
> +		.hwtstamp	= ns_to_ktime(ts_ns),
> +	};
> +}
> +
>  /**
>   * ice_process_skb_fields - Populate skb header fields from Rx descriptor
>   * @rx_ring: Rx descriptor ring packet is being transacted on
> @@ -209,7 +232,7 @@ ice_process_skb_fields(struct ice_rx_ring *rx_ring,
>  	ice_rx_csum(rx_ring, skb, rx_desc, ptype);
>  
>  	if (rx_ring->ptp_rx)
> -		ice_ptp_rx_hwtstamp(rx_ring, rx_desc, skb);
> +		ice_ptp_rx_hwts_to_skb(rx_ring, rx_desc, skb);
>  }
>  
>  /**
> -- 
> 2.41.0
> 
>