net/mlx5: Change interrupt handler to call chain notifier

Multiple EQs may share the same IRQ in subsequent patches.

Instead of calling the IRQ handler directly, the EQ will register
to an atomic chain notfier.

The Linux built-in shared IRQ is not used because it forces the caller
to disable the IRQ and clear affinity before free_irq() can be called.

This patch is the first step in the separation of IRQ and EQ logic.
Signed-off-by: Yuval Avnery <yuvalav@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/infiniband/hw/mlx5/mlx5_ib.h

@@ -920,6 +920,7 @@ struct mlx5_ib_lb_state {
 };
 
 struct mlx5_ib_pf_eq {
+	struct notifier_block irq_nb;
 	struct mlx5_ib_dev *dev;
 	struct mlx5_eq *core;
 	struct work_struct work;

drivers/infiniband/hw/mlx5/odp.c

@@ -1488,9 +1488,11 @@ static void mlx5_ib_eq_pf_process(struct mlx5_ib_pf_eq *eq)
 	mlx5_eq_update_ci(eq->core, cc, 1);
 }
 
-static irqreturn_t mlx5_ib_eq_pf_int(int irq, void *eq_ptr)
+static int mlx5_ib_eq_pf_int(struct notifier_block *nb, unsigned long type,
+			     void *data)
 {
-	struct mlx5_ib_pf_eq *eq = eq_ptr;
+	struct mlx5_ib_pf_eq *eq =
+		container_of(nb, struct mlx5_ib_pf_eq, irq_nb);
 	unsigned long flags;
 
 	if (spin_trylock_irqsave(&eq->lock, flags)) {
@@ -1553,12 +1555,12 @@ mlx5_ib_create_pf_eq(struct mlx5_ib_dev *dev, struct mlx5_ib_pf_eq *eq)
 		goto err_mempool;
 	}
 
+	eq->irq_nb.notifier_call = mlx5_ib_eq_pf_int;
 	param = (struct mlx5_eq_param) {
 		.index = MLX5_EQ_PFAULT_IDX,
 		.mask = 1 << MLX5_EVENT_TYPE_PAGE_FAULT,
 		.nent = MLX5_IB_NUM_PF_EQE,
-		.context = eq,
-		.handler = mlx5_ib_eq_pf_int
+		.nb = &eq->irq_nb,
 	};
 	eq->core = mlx5_eq_create_generic(dev->mdev, "mlx5_ib_page_fault_eq", &param);
 	if (IS_ERR(eq->core)) {

drivers/net/ethernet/mellanox/mlx5/core/lib/eq.h

@@ -34,10 +34,17 @@ struct mlx5_eq {
 	u8                      eqn;
 	int                     nent;
 	struct mlx5_rsc_debug   *dbg;
+	struct notifier_block   *irq_nb; /* For destroy only */
+};
+
+struct mlx5_eq_async {
+	struct mlx5_eq          core;
+	struct notifier_block   irq_nb;
 };
 
 struct mlx5_eq_comp {
-	struct mlx5_eq          core; /* Must be first */
+	struct mlx5_eq          core;
+	struct notifier_block   irq_nb;
 	struct mlx5_eq_tasklet  tasklet_ctx;
 	struct list_head        list;
 };

include/linux/mlx5/eq.h

@@ -26,8 +26,7 @@ struct mlx5_eq_param {
 	u8             index;
 	int            nent;
 	u64            mask;
-	void          *context;
-	irq_handler_t  handler;
+	struct notifier_block *nb;
 };
 
 struct mlx5_eq *