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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Alexander Duyck , Ong Boon Leong , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, xdp-hints@xdp-project.net X-Mailman-Version: 3.3.8 Precedence: list Subject: [xdp-hints] Re: [PATCH net-next 3/4] net: stmmac: add Rx HWTS metadata to XDP receive pkt List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 04/10, Song Yoong Siang wrote: > Add receive hardware timestamp metadata support via kfunc to XDP receive > packets. > > Signed-off-by: Song Yoong Siang > --- > drivers/net/ethernet/stmicro/stmmac/stmmac.h | 1 + > .../net/ethernet/stmicro/stmmac/stmmac_main.c | 24 +++++++++++++++++-- > 2 files changed, 23 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > index ac8ccf851708..760445275da8 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > @@ -94,6 +94,7 @@ struct stmmac_rx_buffer { > > struct stmmac_xdp_buff { > struct xdp_buff xdp; > + ktime_t rx_hwts; > }; > > struct stmmac_rx_queue { > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index f7bbdf04d20c..ca183fbfde85 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -5307,6 +5307,8 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > } > } > [..] > + stmmac_get_rx_hwtstamp(priv, p, np, &ctx.rx_hwts); Do we want to pay this cost for every packet? The preferred alternative is to store enough state in the stmmac_xdp_buff so we can get to this data from stmmac_xdp_rx_timestamp. I haven't read this code, but tentatively: - move priv, p, np into stmmac_xdp_buff, assign them here instead of calling stmmac_get_rx_hwtstamp - call stmmac_get_rx_hwtstamp from stmmac_xdp_rx_timestamp with the stored priv, p, np That would ensure that we won't waste the cycles pulling out the rx timestamp for every packet if the higher levels / users don't care. Would something like this work? > + > if (!skb) { > unsigned int pre_len, sync_len; > > @@ -5315,7 +5317,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > > xdp_init_buff(&ctx.xdp, buf_sz, &rx_q->xdp_rxq); > xdp_prepare_buff(&ctx.xdp, page_address(buf->page), > - buf->page_offset, buf1_len, false); > + buf->page_offset, buf1_len, true); > > pre_len = ctx.xdp.data_end - ctx.xdp.data_hard_start - > buf->page_offset; > @@ -5411,7 +5413,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > > shhwtstamp = skb_hwtstamps(skb); > memset(shhwtstamp, 0, sizeof(struct skb_shared_hwtstamps)); > - stmmac_get_rx_hwtstamp(priv, p, np, &shhwtstamp->hwtstamp); > + shhwtstamp->hwtstamp = ctx.rx_hwts; > > stmmac_rx_vlan(priv->dev, skb); > skb->protocol = eth_type_trans(skb, priv->dev); > @@ -7071,6 +7073,22 @@ void stmmac_fpe_handshake(struct stmmac_priv *priv, bool enable) > } > } > > +static int stmmac_xdp_rx_timestamp(const struct xdp_md *_ctx, u64 *timestamp) > +{ > + const struct stmmac_xdp_buff *ctx = (void *)_ctx; > + > + if (ctx->rx_hwts) { > + *timestamp = ctx->rx_hwts; > + return 0; > + } > + > + return -ENODATA; > +} > + > +const struct xdp_metadata_ops stmmac_xdp_metadata_ops = { > + .xmo_rx_timestamp = stmmac_xdp_rx_timestamp, > +}; > + > /** > * stmmac_dvr_probe > * @device: device pointer > @@ -7178,6 +7196,8 @@ int stmmac_dvr_probe(struct device *device, > > ndev->netdev_ops = &stmmac_netdev_ops; > > + ndev->xdp_metadata_ops = &stmmac_xdp_metadata_ops; > + > ndev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM | > NETIF_F_RXCSUM; > ndev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT | > -- > 2.34.1 >