On Mon, Nov 23, 2020 at 07:36:22PM +0200, Camelia Groza wrote:
> Use an xdp_frame structure for managing the frame. Store a backpointer to
> the structure at the start of the buffer before enqueueing for cleanup
> on TX confirmation. Reserve DPAA_TX_PRIV_DATA_SIZE bytes from the frame
> size shared with the XDP program for this purpose. Use the XDP
> API for freeing the buffer when it returns to the driver on the TX
> confirmation path.
>
> The frame queues are shared with the netstack.
Can you also provide the info from cover letter about locklessness (is
that even a word?) in here?
One question below and:
Reviewed-by: Maciej Fijalkowski <maciej.fijalkow...@intel.com>
>
> This approach will be reused for XDP REDIRECT.
>
> Acked-by: Madalin Bucur <madalin.bu...@oss.nxp.com>
> Signed-off-by: Camelia Groza <camelia.gr...@nxp.com>
> ---
> Changes in v4:
> - call xdp_rxq_info_is_reg() before unregistering
> - minor cleanups (remove unneeded variable, print error code)
> - add more details in the commit message
> - did not call qman_destroy_fq() in case of xdp_rxq_info_reg() failure
> since it would lead to a double free of the fq resources
>
> drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 128
> ++++++++++++++++++++++++-
> drivers/net/ethernet/freescale/dpaa/dpaa_eth.h | 2 +
> 2 files changed, 125 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> index ee076f4..0deffcc 100644
> --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> @@ -1130,6 +1130,24 @@ static int dpaa_fq_init(struct dpaa_fq *dpaa_fq, bool
> td_enable)
>
> dpaa_fq->fqid = qman_fq_fqid(fq);
>
> + if (dpaa_fq->fq_type == FQ_TYPE_RX_DEFAULT ||
> + dpaa_fq->fq_type == FQ_TYPE_RX_PCD) {
> + err = xdp_rxq_info_reg(&dpaa_fq->xdp_rxq, dpaa_fq->net_dev,
> + dpaa_fq->fqid);
> + if (err) {
> + dev_err(dev, "xdp_rxq_info_reg() = %d\n", err);
> + return err;
> + }
> +
> + err = xdp_rxq_info_reg_mem_model(&dpaa_fq->xdp_rxq,
> + MEM_TYPE_PAGE_ORDER0, NULL);
> + if (err) {
> + dev_err(dev, "xdp_rxq_info_reg_mem_model() = %d\n",
> err);
> + xdp_rxq_info_unreg(&dpaa_fq->xdp_rxq);
> + return err;
> + }
> + }
> +
> return 0;
> }
>
> @@ -1159,6 +1177,11 @@ static int dpaa_fq_free_entry(struct device *dev,
> struct qman_fq *fq)
> }
> }
>
> + if ((dpaa_fq->fq_type == FQ_TYPE_RX_DEFAULT ||
> + dpaa_fq->fq_type == FQ_TYPE_RX_PCD) &&
> + xdp_rxq_info_is_reg(&dpaa_fq->xdp_rxq))
> + xdp_rxq_info_unreg(&dpaa_fq->xdp_rxq);
> +
> qman_destroy_fq(fq);
> list_del(&dpaa_fq->list);
>
> @@ -1625,6 +1648,9 @@ static int dpaa_eth_refill_bpools(struct dpaa_priv
> *priv)
> *
> * Return the skb backpointer, since for S/G frames the buffer containing it
> * gets freed here.
> + *
> + * No skb backpointer is set when transmitting XDP frames. Cleanup the buffer
> + * and return NULL in this case.
> */
> static struct sk_buff *dpaa_cleanup_tx_fd(const struct dpaa_priv *priv,
> const struct qm_fd *fd, bool ts)
> @@ -1664,13 +1690,21 @@ static struct sk_buff *dpaa_cleanup_tx_fd(const
> struct dpaa_priv *priv,
> }
> } else {
> dma_unmap_single(priv->tx_dma_dev, addr,
> - priv->tx_headroom + qm_fd_get_length(fd),
> + qm_fd_get_offset(fd) + qm_fd_get_length(fd),
> dma_dir);
> }
>
> swbp = (struct dpaa_eth_swbp *)vaddr;
> skb = swbp->skb;
>
> + /* No skb backpointer is set when running XDP. An xdp_frame
> + * backpointer is saved instead.
> + */
> + if (!skb) {
> + xdp_return_frame(swbp->xdpf);
> + return NULL;
> + }
> +
> /* DMA unmapping is required before accessing the HW provided info */
> if (ts && priv->tx_tstamp &&
> skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
> @@ -2350,11 +2384,76 @@ static enum qman_cb_dqrr_result rx_error_dqrr(struct
> qman_portal *portal,
> return qman_cb_dqrr_consume;
> }
>
> +static int dpaa_xdp_xmit_frame(struct net_device *net_dev,
> + struct xdp_frame *xdpf)
> +{
> + struct dpaa_priv *priv = netdev_priv(net_dev);
> + struct rtnl_link_stats64 *percpu_stats;
> + struct dpaa_percpu_priv *percpu_priv;
> + struct dpaa_eth_swbp *swbp;
> + struct netdev_queue *txq;
> + void *buff_start;
> + struct qm_fd fd;
> + dma_addr_t addr;
> + int err;
> +
> + percpu_priv = this_cpu_ptr(priv->percpu_priv);
> + percpu_stats = &percpu_priv->stats;
> +
> + if (xdpf->headroom < DPAA_TX_PRIV_DATA_SIZE) {
> + err = -EINVAL;
> + goto out_error;
> + }
> +
> + buff_start = xdpf->data - xdpf->headroom;
> +
> + /* Leave empty the skb backpointer at the start of the buffer.
> + * Save the XDP frame for easy cleanup on confirmation.
> + */
> + swbp = (struct dpaa_eth_swbp *)buff_start;
> + swbp->skb = NULL;
> + swbp->xdpf = xdpf;
> +
> + qm_fd_clear_fd(&fd);
> + fd.bpid = FSL_DPAA_BPID_INV;
> + fd.cmd |= cpu_to_be32(FM_FD_CMD_FCO);
> + qm_fd_set_contig(&fd, xdpf->headroom, xdpf->len);
> +
> + addr = dma_map_single(priv->tx_dma_dev, buff_start,
> + xdpf->headroom + xdpf->len,
> + DMA_TO_DEVICE);
Not sure if I asked that. What is the purpose for including the headroom
in frame being set? I would expect to take into account only frame from
xdpf->data.
> + if (unlikely(dma_mapping_error(priv->tx_dma_dev, addr))) {
> + err = -EINVAL;
> + goto out_error;
> + }
> +
> + qm_fd_addr_set64(&fd, addr);
> +
> + /* Bump the trans_start */
> + txq = netdev_get_tx_queue(net_dev, smp_processor_id());
> + txq->trans_start = jiffies;
> +
> + err = dpaa_xmit(priv, percpu_stats, smp_processor_id(), &fd);
> + if (err) {
> + dma_unmap_single(priv->tx_dma_dev, addr,
> + qm_fd_get_offset(&fd) + qm_fd_get_length(&fd),
> + DMA_TO_DEVICE);
> + goto out_error;
> + }
> +
> + return 0;
> +
> +out_error:
> + percpu_stats->tx_errors++;
> + return err;
> +}
> +
> static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void
> *vaddr,
> - unsigned int *xdp_meta_len)
> + struct dpaa_fq *dpaa_fq, unsigned int *xdp_meta_len)
> {
> ssize_t fd_off = qm_fd_get_offset(fd);
> struct bpf_prog *xdp_prog;
> + struct xdp_frame *xdpf;
> struct xdp_buff xdp;
> u32 xdp_act;
>
> @@ -2370,7 +2469,8 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct
> qm_fd *fd, void *vaddr,
> xdp.data_meta = xdp.data;
> xdp.data_hard_start = xdp.data - XDP_PACKET_HEADROOM;
> xdp.data_end = xdp.data + qm_fd_get_length(fd);
> - xdp.frame_sz = DPAA_BP_RAW_SIZE;
> + xdp.frame_sz = DPAA_BP_RAW_SIZE - DPAA_TX_PRIV_DATA_SIZE;
> + xdp.rxq = &dpaa_fq->xdp_rxq;
>
> xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
>
> @@ -2381,6 +2481,22 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct
> qm_fd *fd, void *vaddr,
> case XDP_PASS:
> *xdp_meta_len = xdp.data - xdp.data_meta;
> break;
> + case XDP_TX:
> + /* We can access the full headroom when sending the frame
> + * back out
> + */
> + xdp.data_hard_start = vaddr;
> + xdp.frame_sz = DPAA_BP_RAW_SIZE;
> + xdpf = xdp_convert_buff_to_frame(&xdp);
> + if (unlikely(!xdpf)) {
> + free_pages((unsigned long)vaddr, 0);
> + break;
> + }
> +
> + if (dpaa_xdp_xmit_frame(priv->net_dev, xdpf))
> + xdp_return_frame_rx_napi(xdpf);
> +
> + break;
> default:
> bpf_warn_invalid_xdp_action(xdp_act);
> fallthrough;
> @@ -2415,6 +2531,7 @@ static enum qman_cb_dqrr_result rx_default_dqrr(struct
> qman_portal *portal,
> u32 fd_status, hash_offset;
> struct qm_sg_entry *sgt;
> struct dpaa_bp *dpaa_bp;
> + struct dpaa_fq *dpaa_fq;
> struct dpaa_priv *priv;
> struct sk_buff *skb;
> int *count_ptr;
> @@ -2423,9 +2540,10 @@ static enum qman_cb_dqrr_result rx_default_dqrr(struct
> qman_portal *portal,
> u32 hash;
> u64 ns;
>
> + dpaa_fq = container_of(fq, struct dpaa_fq, fq_base);
> fd_status = be32_to_cpu(fd->status);
> fd_format = qm_fd_get_format(fd);
> - net_dev = ((struct dpaa_fq *)fq)->net_dev;
> + net_dev = dpaa_fq->net_dev;
> priv = netdev_priv(net_dev);
> dpaa_bp = dpaa_bpid2pool(dq->fd.bpid);
> if (!dpaa_bp)
> @@ -2494,7 +2612,7 @@ static enum qman_cb_dqrr_result rx_default_dqrr(struct
> qman_portal *portal,
>
> if (likely(fd_format == qm_fd_contig)) {
> xdp_act = dpaa_run_xdp(priv, (struct qm_fd *)fd, vaddr,
> - &xdp_meta_len);
> + dpaa_fq, &xdp_meta_len);
> if (xdp_act != XDP_PASS) {
> percpu_stats->rx_packets++;
> percpu_stats->rx_bytes += qm_fd_get_length(fd);
> diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> index 94e8613..5c8d52a 100644
> --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> @@ -68,6 +68,7 @@ struct dpaa_fq {
> u16 channel;
> u8 wq;
> enum dpaa_fq_type fq_type;
> + struct xdp_rxq_info xdp_rxq;
> };
>
> struct dpaa_fq_cbs {
> @@ -150,6 +151,7 @@ struct dpaa_buffer_layout {
> */
> struct dpaa_eth_swbp {
> struct sk_buff *skb;
> + struct xdp_frame *xdpf;
> };
>
> struct dpaa_priv {
> --
> 1.9.1
>
