netdev - [net-next 5/9] net/mlx5e: XDP, Replace boolean doorbell indication with segment pointer

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Date:   Thu, 20 Dec 2018 23:06:43 -0800
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...lanox.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Tal Gilboa <talgi@...lanox.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Pawel Staszewski <pstaszewski@...are.pl>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 5/9] net/mlx5e: XDP, Replace boolean doorbell indication with segment pointer

From: Tariq Toukan <tariqt@...lanox.com>

Instead of calculating the control segment to be used upon an
XDP xmit doorbell, save it in SQ structure.
Nullify when no pending doorbell.

Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en.h     |  2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 14 ++++----------
 drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h | 11 ++++-------
 3 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 15cbf0c6e309..35cd4099feda 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -413,7 +413,7 @@ struct mlx5e_xdpsq {
 
 	/* dirtied @xmit */
 	u16                        pc ____cacheline_aligned_in_smp;
-	bool                       doorbell;
+	struct mlx5_wqe_ctrl_seg   *doorbell_cseg;
 
 	struct mlx5e_cq            cq;
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index 407e285b0430..fb1cdf729efb 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -126,11 +126,8 @@ bool mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xdp_info *xdpi)
 	}
 
 	if (unlikely(!mlx5e_wqc_has_room_for(wq, sq->cc, sq->pc, 1))) {
-		if (sq->doorbell) {
-			/* SQ is full, ring doorbell */
-			mlx5e_xmit_xdp_doorbell(sq);
-			sq->doorbell = false;
-		}
+		/* SQ is full, ring doorbell */
+		mlx5e_xmit_xdp_doorbell(sq);
 		stats->full++;
 		return false;
 	}
@@ -158,7 +155,7 @@ bool mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xdp_info *xdpi)
 	sq->db.xdpi[pi] = *xdpi;
 	sq->pc++;
 
-	sq->doorbell = true;
+	sq->doorbell_cseg = cseg;
 
 	stats->xmit++;
 	return true;
@@ -309,10 +306,7 @@ void mlx5e_xdp_rx_poll_complete(struct mlx5e_rq *rq)
 {
 	struct mlx5e_xdpsq *xdpsq = &rq->xdpsq;
 
-	if (xdpsq->doorbell) {
-		mlx5e_xmit_xdp_doorbell(xdpsq);
-		xdpsq->doorbell = false;
-	}
+	mlx5e_xmit_xdp_doorbell(xdpsq);
 
 	if (xdpsq->redirect_flush) {
 		xdp_do_flush_map();
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
index 37fcb17e7f27..e2faf869e77c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
@@ -51,13 +51,10 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 
 static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_xdpsq *sq)
 {
-	struct mlx5_wq_cyc *wq = &sq->wq;
-	struct mlx5e_tx_wqe *wqe;
-	u16 pi = mlx5_wq_cyc_ctr2ix(wq, sq->pc - 1); /* last pi */
-
-	wqe  = mlx5_wq_cyc_get_wqe(wq, pi);
-
-	mlx5e_notify_hw(wq, sq->pc, sq->uar_map, &wqe->ctrl);
+	if (sq->doorbell_cseg) {
+		mlx5e_notify_hw(&sq->wq, sq->pc, sq->uar_map, sq->doorbell_cseg);
+		sq->doorbell_cseg = NULL;
+	}
 }
 
 #endif
-- 
2.19.2