net/mlx4_en: Add Low Latency Socket (LLS) support

Add basic support for LLS.

Signed-off-by: Amir Vadai <amirv@mellanox.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 121 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index b1f51c1f635c..11c862e4e69d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -310,6 +310,19 @@ struct mlx4_en_cq {
 	u16 moder_cnt;
 	struct mlx4_cqe *buf;
 #define MLX4_EN_OPCODE_ERROR	0x1e
+
+#ifdef CONFIG_NET_LL_RX_POLL
+	unsigned int state;
+#define MLX4_EN_CQ_STATE_IDLE        0
+#define MLX4_EN_CQ_STATE_NAPI     1    /* NAPI owns this CQ */
+#define MLX4_EN_CQ_STATE_POLL     2    /* poll owns this CQ */
+#define MLX4_CQ_LOCKED (MLX4_EN_CQ_STATE_NAPI | MLX4_EN_CQ_STATE_POLL)
+#define MLX4_EN_CQ_STATE_NAPI_YIELD  4    /* NAPI yielded this CQ */
+#define MLX4_EN_CQ_STATE_POLL_YIELD  8    /* poll yielded this CQ */
+#define CQ_YIELD (MLX4_EN_CQ_STATE_NAPI_YIELD | MLX4_EN_CQ_STATE_POLL_YIELD)
+#define CQ_USER_PEND (MLX4_EN_CQ_STATE_POLL | MLX4_EN_CQ_STATE_POLL_YIELD)
+	spinlock_t poll_lock; /* protects from LLS/napi conflicts */
+#endif  /* CONFIG_NET_LL_RX_POLL */
 };
 
 struct mlx4_en_port_profile {
@@ -562,6 +575,114 @@ struct mlx4_mac_entry {
 	struct rcu_head rcu;
 };
 
+#ifdef CONFIG_NET_LL_RX_POLL
+static inline void mlx4_en_cq_init_lock(struct mlx4_en_cq *cq)
+{
+	spin_lock_init(&cq->poll_lock);
+	cq->state = MLX4_EN_CQ_STATE_IDLE;
+}
+
+/* called from the device poll rutine to get ownership of a cq */
+static inline bool mlx4_en_cq_lock_napi(struct mlx4_en_cq *cq)
+{
+	int rc = true;
+	spin_lock(&cq->poll_lock);
+	if (cq->state & MLX4_CQ_LOCKED) {
+		WARN_ON(cq->state & MLX4_EN_CQ_STATE_NAPI);
+		cq->state |= MLX4_EN_CQ_STATE_NAPI_YIELD;
+		rc = false;
+	} else
+		/* we don't care if someone yielded */
+		cq->state = MLX4_EN_CQ_STATE_NAPI;
+	spin_unlock(&cq->poll_lock);
+	return rc;
+}
+
+/* returns true is someone tried to get the cq while napi had it */
+static inline bool mlx4_en_cq_unlock_napi(struct mlx4_en_cq *cq)
+{
+	int rc = false;
+	spin_lock(&cq->poll_lock);
+	WARN_ON(cq->state & (MLX4_EN_CQ_STATE_POLL |
+			       MLX4_EN_CQ_STATE_NAPI_YIELD));
+
+	if (cq->state & MLX4_EN_CQ_STATE_POLL_YIELD)
+		rc = true;
+	cq->state = MLX4_EN_CQ_STATE_IDLE;
+	spin_unlock(&cq->poll_lock);
+	return rc;
+}
+
+/* called from mlx4_en_low_latency_poll() */
+static inline bool mlx4_en_cq_lock_poll(struct mlx4_en_cq *cq)
+{
+	int rc = true;
+	spin_lock_bh(&cq->poll_lock);
+	if ((cq->state & MLX4_CQ_LOCKED)) {
+		struct net_device *dev = cq->dev;
+		struct mlx4_en_priv *priv = netdev_priv(dev);
+		struct mlx4_en_rx_ring *rx_ring = &priv->rx_ring[cq->ring];
+
+		cq->state |= MLX4_EN_CQ_STATE_POLL_YIELD;
+		rc = false;
+	} else
+		/* preserve yield marks */
+		cq->state |= MLX4_EN_CQ_STATE_POLL;
+	spin_unlock_bh(&cq->poll_lock);
+	return rc;
+}
+
+/* returns true if someone tried to get the cq while it was locked */
+static inline bool mlx4_en_cq_unlock_poll(struct mlx4_en_cq *cq)
+{
+	int rc = false;
+	spin_lock_bh(&cq->poll_lock);
+	WARN_ON(cq->state & (MLX4_EN_CQ_STATE_NAPI));
+
+	if (cq->state & MLX4_EN_CQ_STATE_POLL_YIELD)
+		rc = true;
+	cq->state = MLX4_EN_CQ_STATE_IDLE;
+	spin_unlock_bh(&cq->poll_lock);
+	return rc;
+}
+
+/* true if a socket is polling, even if it did not get the lock */
+static inline bool mlx4_en_cq_ll_polling(struct mlx4_en_cq *cq)
+{
+	WARN_ON(!(cq->state & MLX4_CQ_LOCKED));
+	return cq->state & CQ_USER_PEND;
+}
+#else
+static inline void mlx4_en_cq_init_lock(struct mlx4_en_cq *cq)
+{
+}
+
+static inline bool mlx4_en_cq_lock_napi(struct mlx4_en_cq *cq)
+{
+	return true;
+}
+
+static inline bool mlx4_en_cq_unlock_napi(struct mlx4_en_cq *cq)
+{
+	return false;
+}
+
+static inline bool mlx4_en_cq_lock_poll(struct mlx4_en_cq *cq)
+{
+	return false;
+}
+
+static inline bool mlx4_en_cq_unlock_poll(struct mlx4_en_cq *cq)
+{
+	return false;
+}
+
+static inline bool mlx4_en_cq_ll_polling(struct mlx4_en_cq *cq)
+{
+	return false;
+}
+#endif /* CONFIG_NET_LL_RX_POLL */
+
 #define MLX4_EN_WOL_DO_MODIFY (1ULL << 63)
 
 void mlx4_en_update_loopback_state(struct net_device *dev,