net/mlx5: Delay IRQ destruction till all users are gone

Shared IRQ are consumed by multiple EQ users and in order to properly
initialize and later release such IRQs, we add kref counting of IRQ
structure.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -16,6 +16,8 @@ struct mlx5_irq {
 	struct atomic_notifier_head nh;
 	cpumask_var_t mask;
 	char name[MLX5_MAX_IRQ_NAME];
+	struct kref kref;
+	int irqn;
 };
 
 struct mlx5_irq_table {
@@ -146,13 +148,35 @@ int mlx5_set_msix_vec_count(struct mlx5_core_dev *dev, int function_id,
 	return ret;
 }
 
+static void irq_release(struct kref *kref)
+{
+	struct mlx5_irq *irq = container_of(kref, struct mlx5_irq, kref);
+
+	free_irq(irq->irqn, &irq->nh);
+}
+
+static void irq_put(struct mlx5_irq *irq)
+{
+	kref_put(&irq->kref, irq_release);
+}
+
 int mlx5_irq_attach_nb(struct mlx5_irq_table *irq_table, int vecidx,
 		       struct notifier_block *nb)
 {
 	struct mlx5_irq *irq;
+	int err;
 
 	irq = &irq_table->irq[vecidx];
-	return atomic_notifier_chain_register(&irq->nh, nb);
+	err = kref_get_unless_zero(&irq->kref);
+	if (WARN_ON_ONCE(!err))
+		/* Something very bad happens here, we are enabling EQ
+		 * on non-existing IRQ.
+		 */
+		return -ENOENT;
+	err = atomic_notifier_chain_register(&irq->nh, nb);
+	if (err)
+		irq_put(irq);
+	return err;
 }
 
 int mlx5_irq_detach_nb(struct mlx5_irq_table *irq_table, int vecidx,
@@ -161,6 +185,7 @@ int mlx5_irq_detach_nb(struct mlx5_irq_table *irq_table, int vecidx,
 	struct mlx5_irq *irq;
 
 	irq = &irq_table->irq[vecidx];
+	irq_put(irq);
 	return atomic_notifier_chain_unregister(&irq->nh, nb);
 }
 
@@ -189,28 +214,26 @@ static int request_irqs(struct mlx5_core_dev *dev, int nvec)
 
 	for (i = 0; i < nvec; i++) {
 		struct mlx5_irq *irq = mlx5_irq_get(dev, i);
-		int irqn = pci_irq_vector(dev->pdev, i);
 
+		irq->irqn = pci_irq_vector(dev->pdev, i);
 		irq_set_name(name, i);
 		ATOMIC_INIT_NOTIFIER_HEAD(&irq->nh);
 		snprintf(irq->name, MLX5_MAX_IRQ_NAME,
 			 "%s@pci:%s", name, pci_name(dev->pdev));
-		err = request_irq(irqn, mlx5_irq_int_handler, 0, irq->name,
+		err = request_irq(irq->irqn, mlx5_irq_int_handler, 0, irq->name,
 				  &irq->nh);
 		if (err) {
 			mlx5_core_err(dev, "Failed to request irq\n");
 			goto err_request_irq;
 		}
+		kref_init(&irq->kref);
 	}
 	return 0;
 
 err_request_irq:
-	while (i--) {
-		struct mlx5_irq *irq = mlx5_irq_get(dev, i);
-		int irqn = pci_irq_vector(dev->pdev, i);
+	while (i--)
+		irq_put(mlx5_irq_get(dev, i));
 
-		free_irq(irqn, &irq->nh);
-	}
 	return  err;
 }
 
@@ -264,10 +287,8 @@ static int set_comp_irq_affinity_hint(struct mlx5_core_dev *mdev, int i)
 {
 	int vecidx = MLX5_IRQ_VEC_COMP_BASE + i;
 	struct mlx5_irq *irq;
-	int irqn;
 
 	irq = mlx5_irq_get(mdev, vecidx);
-	irqn = pci_irq_vector(mdev->pdev, vecidx);
 	if (!zalloc_cpumask_var(&irq->mask, GFP_KERNEL)) {
 		mlx5_core_warn(mdev, "zalloc_cpumask_var failed");
 		return -ENOMEM;
@@ -276,9 +297,9 @@ static int set_comp_irq_affinity_hint(struct mlx5_core_dev *mdev, int i)
 	cpumask_set_cpu(cpumask_local_spread(i, mdev->priv.numa_node),
 			irq->mask);
 	if (IS_ENABLED(CONFIG_SMP) &&
-	    irq_set_affinity_hint(irqn, irq->mask))
+	    irq_set_affinity_hint(irq->irqn, irq->mask))
 		mlx5_core_warn(mdev, "irq_set_affinity_hint failed, irq 0x%.4x",
-			       irqn);
+			       irq->irqn);
 
 	return 0;
 }
@@ -287,11 +308,9 @@ static void clear_comp_irq_affinity_hint(struct mlx5_core_dev *mdev, int i)
 {
 	int vecidx = MLX5_IRQ_VEC_COMP_BASE + i;
 	struct mlx5_irq *irq;
-	int irqn;
 
 	irq = mlx5_irq_get(mdev, vecidx);
-	irqn = pci_irq_vector(mdev->pdev, vecidx);
-	irq_set_affinity_hint(irqn, NULL);
+	irq_set_affinity_hint(irq->irqn, NULL);
 	free_cpumask_var(irq->mask);
 }
 
@@ -344,8 +363,7 @@ static void unrequest_irqs(struct mlx5_core_dev *dev)
 	int i;
 
 	for (i = 0; i < table->nvec; i++)
-		free_irq(pci_irq_vector(dev->pdev, i),
-			 &mlx5_irq_get(dev, i)->nh);
+		irq_put(mlx5_irq_get(dev, i));
 }
 
 int mlx5_irq_table_create(struct mlx5_core_dev *dev)
@@ -422,8 +440,7 @@ void mlx5_irq_table_destroy(struct mlx5_core_dev *dev)
 	irq_clear_rmap(dev);
 	clear_comp_irqs_affinity_hints(dev);
 	for (i = 0; i < table->nvec; i++)
-		free_irq(pci_irq_vector(dev->pdev, i),
-			 &mlx5_irq_get(dev, i)->nh);
+		irq_release(&mlx5_irq_get(dev, i)->kref);
 	pci_free_irq_vectors(dev->pdev);
 	kfree(table->irq);
 }