mlx4: Replace the mlx4_interface.event callback with a notifier

Use a notifier to implement mlx4_dispatch_event() in preparation to
switch mlx4_en and mlx4_ib to be an auxiliary device.

A problem is that if the mlx4_interface.event callback was replaced with
something as mlx4_adrv.event then the implementation of
mlx4_dispatch_event() would need to acquire a lock on a given device
before executing this callback. That is necessary because otherwise
there is no guarantee that the associated driver cannot get unbound when
the callback is running. However, taking this lock is not possible
because mlx4_dispatch_event() can be invoked from the hardirq context.
Using an atomic notifier allows the driver to accurately record when it
wants to receive these events and solves this problem.

A handler registration is done by both mlx4_en and mlx4_ib at the end of
their mlx4_interface.add callback. This matches the current situation
when mlx4_add_device() would enable events for a given device
immediately after this callback, by adding the device on the
mlx4_priv.list.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Tested-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 41 insertions, 15 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_main.c b/drivers/net/ethernet/mellanox/mlx4/en_main.c
index 83dae886ade6..31bf625b8158 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_main.c
@@ -183,10 +183,12 @@ static void mlx4_en_get_profile(struct mlx4_en_dev *mdev)
 	}
 }
 
-static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
-			  enum mlx4_dev_event event, void *param)
+static int mlx4_en_event(struct notifier_block *this, unsigned long event,
+			 void *param)
 {
-	struct mlx4_en_dev *mdev = (struct mlx4_en_dev *) endev_ptr;
+	struct mlx4_en_dev *mdev =
+		container_of(this, struct mlx4_en_dev, mlx_nb);
+	struct mlx4_dev *dev = mdev->dev;
 	struct mlx4_en_priv *priv;
 	int port;
 
@@ -205,7 +207,7 @@ static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
 	case MLX4_DEV_EVENT_PORT_UP:
 	case MLX4_DEV_EVENT_PORT_DOWN:
 		if (!mdev->pndev[port])
-			return;
+			return NOTIFY_DONE;
 		priv = netdev_priv(mdev->pndev[port]);
 		/* To prevent races, we poll the link state in a separate
 		  task rather than changing it here */
@@ -224,10 +226,12 @@ static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
 	default:
 		if (port < 1 || port > dev->caps.num_ports ||
 		    !mdev->pndev[port])
-			return;
-		mlx4_warn(mdev, "Unhandled event %d for port %d\n", event,
+			return NOTIFY_DONE;
+		mlx4_warn(mdev, "Unhandled event %d for port %d\n", (int)event,
 			  port);
 	}
+
+	return NOTIFY_DONE;
 }
 
 static void mlx4_en_remove(struct mlx4_dev *dev, void *endev_ptr)
@@ -235,6 +239,8 @@ static void mlx4_en_remove(struct mlx4_dev *dev, void *endev_ptr)
 	struct mlx4_en_dev *mdev = endev_ptr;
 	int i;
 
+	mlx4_unregister_event_notifier(dev, &mdev->mlx_nb);
+
 	mutex_lock(&mdev->state_lock);
 	mdev->device_up = false;
 	mutex_unlock(&mdev->state_lock);
@@ -276,7 +282,7 @@ static void mlx4_en_activate(struct mlx4_dev *dev, void *ctx)
 static void *mlx4_en_add(struct mlx4_dev *dev)
 {
 	struct mlx4_en_dev *mdev;
-	int i;
+	int err, i;
 
 	printk_once(KERN_INFO "%s", mlx4_en_version);
 
@@ -339,6 +345,11 @@ static void *mlx4_en_add(struct mlx4_dev *dev)
 	mutex_init(&mdev->state_lock);
 	mdev->device_up = true;
 
+	/* register mlx4 core notifier */
+	mdev->mlx_nb.notifier_call = mlx4_en_event;
+	err = mlx4_register_event_notifier(dev, &mdev->mlx_nb);
+	WARN(err, "failed to register mlx4 event notifier (%d)", err);
+
 	return mdev;
 
 err_mr:
@@ -359,7 +370,6 @@ err_free_res:
 static struct mlx4_interface mlx4_en_interface = {
 	.add		= mlx4_en_add,
 	.remove		= mlx4_en_remove,
-	.event		= mlx4_en_event,
 	.protocol	= MLX4_PROT_ETH,
 	.activate	= mlx4_en_activate,
 };
diff --git a/drivers/net/ethernet/mellanox/mlx4/intf.c b/drivers/net/ethernet/mellanox/mlx4/intf.c
index a761971cd0c4..fecb63e69607 100644
--- a/drivers/net/ethernet/mellanox/mlx4/intf.c
+++ b/drivers/net/ethernet/mellanox/mlx4/intf.c
@@ -183,17 +183,27 @@ void mlx4_dispatch_event(struct mlx4_dev *dev, enum mlx4_dev_event type,
 			 void *param)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
-	struct mlx4_device_context *dev_ctx;
-	unsigned long flags;
 
-	spin_lock_irqsave(&priv->ctx_lock, flags);
+	atomic_notifier_call_chain(&priv->event_nh, type, param);
+}
 
-	list_for_each_entry(dev_ctx, &priv->ctx_list, list)
-		if (dev_ctx->intf->event)
-			dev_ctx->intf->event(dev, dev_ctx->context, type, param);
+int mlx4_register_event_notifier(struct mlx4_dev *dev,
+				 struct notifier_block *nb)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
 
-	spin_unlock_irqrestore(&priv->ctx_lock, flags);
+	return atomic_notifier_chain_register(&priv->event_nh, nb);
+}
+EXPORT_SYMBOL(mlx4_register_event_notifier);
+
+int mlx4_unregister_event_notifier(struct mlx4_dev *dev,
+				   struct notifier_block *nb)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+
+	return atomic_notifier_chain_unregister(&priv->event_nh, nb);
 }
+EXPORT_SYMBOL(mlx4_unregister_event_notifier);
 
 int mlx4_register_device(struct mlx4_dev *dev)
 {
diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index 8a5409b00530..5f3ba8385e23 100644
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -3378,6 +3378,8 @@ static int mlx4_load_one(struct pci_dev *pdev, int pci_dev_data,
 	INIT_LIST_HEAD(&priv->ctx_list);
 	spin_lock_init(&priv->ctx_lock);
 
+	ATOMIC_INIT_NOTIFIER_HEAD(&priv->event_nh);
+
 	mutex_init(&priv->port_mutex);
 	mutex_init(&priv->bond_mutex);
 
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
index de5699a4ddaa..8dbea814a2f5 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
@@ -47,6 +47,7 @@
 #include <linux/spinlock.h>
 #include <net/devlink.h>
 #include <linux/rwsem.h>
+#include <linux/notifier.h>
 
 #include <linux/mlx4/device.h>
 #include <linux/mlx4/driver.h>
@@ -878,6 +879,7 @@ struct mlx4_priv {
 	struct list_head	dev_list;
 	struct list_head	ctx_list;
 	spinlock_t		ctx_lock;
+	struct atomic_notifier_head event_nh;
 
 	int			pci_dev_data;
 	int                     removed;
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 72a3fea36702..efe3f97b874f 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -49,6 +49,7 @@
 #include <linux/ptp_clock_kernel.h>
 #include <linux/irq.h>
 #include <net/xdp.h>
+#include <linux/notifier.h>
 
 #include <linux/mlx4/device.h>
 #include <linux/mlx4/qp.h>
@@ -433,6 +434,7 @@ struct mlx4_en_dev {
 	struct ptp_clock	*ptp_clock;
 	struct ptp_clock_info	ptp_clock_info;
 	struct notifier_block	netdev_nb;
+	struct notifier_block	mlx_nb;
 };