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>

1 files changed, 17 insertions, 7 deletions

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)
 {