net/mlx5e: XDP, Use multiple single-entry objects in xdpi_fifo

Here we fix the current wi->num_pkts abuse, as it was used to indicate
multiple xdpi entries in the xdpi_fifo.

Instead, reduce mlx5e_xdp_info to the size of a single field, making it
a union of unions. Per packet, use as many instances as needed to
provide the information needed at the time of completion.

The sequence of xdpi instances pushed is well defined, derived by the
xmit_mode.
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -476,7 +476,7 @@ struct mlx5e_txqsq {
 } ____cacheline_aligned_in_smp;
 
 struct mlx5e_xdp_info_fifo {
-	struct mlx5e_xdp_info *xi;
+	union mlx5e_xdp_info *xi;
 	u32 *cc;
 	u32 *pc;
 	u32 mask;

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c

@@ -63,7 +63,6 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 	struct page *page = virt_to_page(xdp->data);
 	struct mlx5e_xmit_data_frags xdptxdf = {};
 	struct mlx5e_xmit_data *xdptxd;
-	struct mlx5e_xdp_info xdpi;
 	struct xdp_frame *xdpf;
 	dma_addr_t dma_addr;
 	int i;
@@ -90,8 +89,6 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 		 */
 		__set_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags); /* non-atomic */
 
-		xdpi.mode = MLX5E_XDP_XMIT_MODE_FRAME;
-
 		if (unlikely(xdptxd->has_frags))
 			return false;
 
@@ -103,14 +100,18 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 		}
 
 		xdptxd->dma_addr = dma_addr;
-		xdpi.frame.xdpf     = xdpf;
-		xdpi.frame.dma_addr = dma_addr;
 
 		if (unlikely(!INDIRECT_CALL_2(sq->xmit_xdp_frame, mlx5e_xmit_xdp_frame_mpwqe,
 					      mlx5e_xmit_xdp_frame, sq, xdptxd, 0)))
 			return false;
 
-		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, &xdpi);
+		/* xmit_mode == MLX5E_XDP_XMIT_MODE_FRAME */
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .mode = MLX5E_XDP_XMIT_MODE_FRAME });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .frame.xdpf = xdpf });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .frame.dma_addr = dma_addr });
 		return true;
 	}
 
@@ -120,9 +121,6 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 	 * mode.
 	 */
 
-	xdpi.mode = MLX5E_XDP_XMIT_MODE_PAGE;
-	xdpi.page.rq = rq;
-
 	dma_addr = page_pool_get_dma_addr(page) + (xdpf->data - (void *)xdpf);
 	dma_sync_single_for_device(sq->pdev, dma_addr, xdptxd->len, DMA_BIDIRECTIONAL);
 
@@ -148,16 +146,28 @@ mlx5e_xmit_xdp_buff(struct mlx5e_xdpsq *sq, struct mlx5e_rq *rq,
 				      mlx5e_xmit_xdp_frame, sq, xdptxd, 0)))
 		return false;
 
-	xdpi.page.page = page;
-	mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, &xdpi);
+	/* xmit_mode == MLX5E_XDP_XMIT_MODE_PAGE */
+	mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+			     (union mlx5e_xdp_info) { .mode = MLX5E_XDP_XMIT_MODE_PAGE });
 
 	if (xdptxd->has_frags) {
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info)
+				     { .page.num = 1 + xdptxdf.sinfo->nr_frags });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .page.page = page });
 		for (i = 0; i < xdptxdf.sinfo->nr_frags; i++) {
 			skb_frag_t *frag = &xdptxdf.sinfo->frags[i];
 
-			xdpi.page.page = skb_frag_page(frag);
-			mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, &xdpi);
+			mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+					     (union mlx5e_xdp_info)
+					     { .page.page = skb_frag_page(frag) });
 		}
+	} else {
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .page.num = 1 });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .page.page = page });
 	}
 
 	return true;
@@ -526,7 +536,6 @@ mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xmit_data *xdptxd,
 	cseg->opmod_idx_opcode = cpu_to_be32((sq->pc << 8) | MLX5_OPCODE_SEND);
 
 	if (test_bit(MLX5E_SQ_STATE_XDP_MULTIBUF, &sq->state)) {
-		u8 num_pkts = 1 + num_frags;
 		int i;
 
 		memset(&cseg->trailer, 0, sizeof(cseg->trailer));
@@ -552,7 +561,7 @@ mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xmit_data *xdptxd,
 
 		sq->db.wqe_info[pi] = (struct mlx5e_xdp_wqe_info) {
 			.num_wqebbs = num_wqebbs,
-			.num_pkts = num_pkts,
+			.num_pkts = 1,
 		};
 
 		sq->pc += num_wqebbs;
@@ -577,20 +586,46 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
 	u16 i;
 
 	for (i = 0; i < wi->num_pkts; i++) {
-		struct mlx5e_xdp_info xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
+		union mlx5e_xdp_info xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
 
 		switch (xdpi.mode) {
-		case MLX5E_XDP_XMIT_MODE_FRAME:
+		case MLX5E_XDP_XMIT_MODE_FRAME: {
 			/* XDP_TX from the XSK RQ and XDP_REDIRECT */
-			dma_unmap_single(sq->pdev, xdpi.frame.dma_addr,
-					 xdpi.frame.xdpf->len, DMA_TO_DEVICE);
-			xdp_return_frame_bulk(xdpi.frame.xdpf, bq);
+			struct xdp_frame *xdpf;
+			dma_addr_t dma_addr;
+
+			xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
+			xdpf = xdpi.frame.xdpf;
+			xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
+			dma_addr = xdpi.frame.dma_addr;
+
+			dma_unmap_single(sq->pdev, dma_addr,
+					 xdpf->len, DMA_TO_DEVICE);
+			xdp_return_frame_bulk(xdpf, bq);
 			break;
-		case MLX5E_XDP_XMIT_MODE_PAGE:
+		}
+		case MLX5E_XDP_XMIT_MODE_PAGE: {
 			/* XDP_TX from the regular RQ */
-			page_pool_put_defragged_page(xdpi.page.rq->page_pool,
-						     xdpi.page.page, -1, true);
+			u8 num, n = 0;
+
+			xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
+			num = xdpi.page.num;
+
+			do {
+				struct page *page;
+
+				xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
+				page = xdpi.page.page;
+
+				/* No need to check ((page->pp_magic & ~0x3UL) == PP_SIGNATURE)
+				 * as we know this is a page_pool page.
+				 */
+				page_pool_put_defragged_page(page->pp,
+							     page, -1, true);
+			} while (++n < num);
+
 			break;
+		}
 		case MLX5E_XDP_XMIT_MODE_XSK:
 			/* AF_XDP send */
 			(*xsk_frames)++;
@@ -726,7 +761,6 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 	for (i = 0; i < n; i++) {
 		struct xdp_frame *xdpf = frames[i];
 		struct mlx5e_xmit_data xdptxd = {};
-		struct mlx5e_xdp_info xdpi;
 		bool ret;
 
 		xdptxd.data = xdpf->data;
@@ -737,10 +771,6 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 		if (unlikely(dma_mapping_error(sq->pdev, xdptxd.dma_addr)))
 			break;
 
-		xdpi.mode           = MLX5E_XDP_XMIT_MODE_FRAME;
-		xdpi.frame.xdpf     = xdpf;
-		xdpi.frame.dma_addr = xdptxd.dma_addr;
-
 		ret = INDIRECT_CALL_2(sq->xmit_xdp_frame, mlx5e_xmit_xdp_frame_mpwqe,
 				      mlx5e_xmit_xdp_frame, sq, &xdptxd, 0);
 		if (unlikely(!ret)) {
@@ -748,7 +778,14 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 					 xdptxd.len, DMA_TO_DEVICE);
 			break;
 		}
-		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, &xdpi);
+
+		/* xmit_mode == MLX5E_XDP_XMIT_MODE_FRAME */
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .mode = MLX5E_XDP_XMIT_MODE_FRAME });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .frame.xdpf = xdpf });
+		mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo,
+				     (union mlx5e_xdp_info) { .frame.dma_addr = xdptxd.dma_addr });
 		nxmit++;
 	}
 

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h

@@ -71,18 +71,30 @@ enum mlx5e_xdp_xmit_mode {
 	MLX5E_XDP_XMIT_MODE_XSK,
 };
 
-struct mlx5e_xdp_info {
+/* xmit_mode entry is pushed to the fifo per packet, followed by multiple
+ * entries, as follows:
+ *
+ * MLX5E_XDP_XMIT_MODE_FRAME:
+ *    xdpf, dma_addr_1, dma_addr_2, ... , dma_addr_num.
+ *    'num' is derived from xdpf.
+ *
+ * MLX5E_XDP_XMIT_MODE_PAGE:
+ *    num, page_1, page_2, ... , page_num.
+ *
+ * MLX5E_XDP_XMIT_MODE_XSK:
+ *    none.
+ */
+union mlx5e_xdp_info {
 	enum mlx5e_xdp_xmit_mode mode;
 	union {
-		struct {
 		struct xdp_frame *xdpf;
 		dma_addr_t dma_addr;
 	} frame;
-		struct {
+	union {
 		struct mlx5e_rq *rq;
+		u8 num;
 		struct page *page;
 	} page;
-	};
 };
 
 struct mlx5e_xsk_param;
@@ -212,14 +224,14 @@ mlx5e_xdp_mpwqe_add_dseg(struct mlx5e_xdpsq *sq,
 
 static inline void
 mlx5e_xdpi_fifo_push(struct mlx5e_xdp_info_fifo *fifo,
-		     struct mlx5e_xdp_info *xi)
+		     union mlx5e_xdp_info xi)
 {
 	u32 i = (*fifo->pc)++ & fifo->mask;
 
-	fifo->xi[i] = *xi;
+	fifo->xi[i] = xi;
 }
 
-static inline struct mlx5e_xdp_info
+static inline union mlx5e_xdp_info
 mlx5e_xdpi_fifo_pop(struct mlx5e_xdp_info_fifo *fifo)
 {
 	return fifo->xi[(*fifo->cc)++ & fifo->mask];

drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c

@@ -44,7 +44,7 @@ int mlx5e_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags)
  * same.
  */
 static void mlx5e_xsk_tx_post_err(struct mlx5e_xdpsq *sq,
-				  struct mlx5e_xdp_info *xdpi)
+				  union mlx5e_xdp_info *xdpi)
 {
 	u16 pi = mlx5_wq_cyc_ctr2ix(&sq->wq, sq->pc);
 	struct mlx5e_xdp_wqe_info *wi = &sq->db.wqe_info[pi];
@@ -54,14 +54,14 @@ static void mlx5e_xsk_tx_post_err(struct mlx5e_xdpsq *sq,
 	wi->num_pkts = 1;
 
 	nopwqe = mlx5e_post_nop(&sq->wq, sq->sqn, &sq->pc);
-	mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, xdpi);
+	mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, *xdpi);
 	sq->doorbell_cseg = &nopwqe->ctrl;
 }
 
 bool mlx5e_xsk_tx(struct mlx5e_xdpsq *sq, unsigned int budget)
 {
 	struct xsk_buff_pool *pool = sq->xsk_pool;
-	struct mlx5e_xdp_info xdpi;
+	union mlx5e_xdp_info xdpi;
 	bool work_done = true;
 	bool flush = false;
 
@@ -105,7 +105,7 @@ bool mlx5e_xsk_tx(struct mlx5e_xdpsq *sq, unsigned int budget)
 
 			mlx5e_xsk_tx_post_err(sq, &xdpi);
 		} else {
-			mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, &xdpi);
+			mlx5e_xdpi_fifo_push(&sq->db.xdpi_fifo, xdpi);
 		}
 
 		flush = true;

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -1300,17 +1300,19 @@ static int mlx5e_alloc_xdpsq_fifo(struct mlx5e_xdpsq *sq, int numa)
 {
 	struct mlx5e_xdp_info_fifo *xdpi_fifo = &sq->db.xdpi_fifo;
 	int wq_sz        = mlx5_wq_cyc_get_size(&sq->wq);
-	int dsegs_per_wq = wq_sz * MLX5_SEND_WQEBB_NUM_DS;
+	int entries = wq_sz * MLX5_SEND_WQEBB_NUM_DS * 2; /* upper bound for maximum num of
+							   * entries of all xmit_modes.
+							   */
 	size_t size;
 
-	size = array_size(sizeof(*xdpi_fifo->xi), dsegs_per_wq);
+	size = array_size(sizeof(*xdpi_fifo->xi), entries);
 	xdpi_fifo->xi = kvzalloc_node(size, GFP_KERNEL, numa);
 	if (!xdpi_fifo->xi)
 		return -ENOMEM;
 
 	xdpi_fifo->pc   = &sq->xdpi_fifo_pc;
 	xdpi_fifo->cc   = &sq->xdpi_fifo_cc;
-	xdpi_fifo->mask = dsegs_per_wq - 1;
+	xdpi_fifo->mask = entries - 1;
 
 	return 0;
 }