net/mlx5: poll cmd EQ in case of command timeout

Once driver detects a command interface command timeout, it warns the
user and returns timeout error to the caller. In such case, the entry of
the command is not evacuated (because only real event interrupt is allowed
to clear command interface entry). If the HW event interrupt
of this entry will never arrive, this entry will be left unused forever.
Command interface entries are limited and eventually we can end up without
the ability to post a new command.

In addition, if driver will not consume the EQE of the lost interrupt and
rearm the EQ, no new interrupts will arrive for other commands.

Add a resiliency mechanism for manually polling the command EQ in case of
a command timeout. In case resiliency mechanism will find non-handled EQE,
it will consume it, and the command interface will be fully functional
again. Once the resiliency flow finished, wait another 5 seconds for the
command interface to complete for this command entry.

Define mlx5_cmd_eq_recover() to manage the cmd EQ polling resiliency flow.
Add an async EQ spinlock to avoid races between resiliency flows and real
interrupts that might run simultaneously.

Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

1 files changed, 39 insertions, 1 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
index 1318d774b18f..22a19d391e17 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
@@ -189,6 +189,29 @@ u32 mlx5_eq_poll_irq_disabled(struct mlx5_eq_comp *eq)
 	return count_eqe;
 }
 
+static void mlx5_eq_async_int_lock(struct mlx5_eq_async *eq, unsigned long *flags)
+	__acquires(&eq->lock)
+{
+	if (in_irq())
+		spin_lock(&eq->lock);
+	else
+		spin_lock_irqsave(&eq->lock, *flags);
+}
+
+static void mlx5_eq_async_int_unlock(struct mlx5_eq_async *eq, unsigned long *flags)
+	__releases(&eq->lock)
+{
+	if (in_irq())
+		spin_unlock(&eq->lock);
+	else
+		spin_unlock_irqrestore(&eq->lock, *flags);
+}
+
+enum async_eq_nb_action {
+	ASYNC_EQ_IRQ_HANDLER = 0,
+	ASYNC_EQ_RECOVER = 1,
+};
+
 static int mlx5_eq_async_int(struct notifier_block *nb,
 			     unsigned long action, void *data)
 {
@@ -198,11 +221,14 @@ static int mlx5_eq_async_int(struct notifier_block *nb,
 	struct mlx5_eq_table *eqt;
 	struct mlx5_core_dev *dev;
 	struct mlx5_eqe *eqe;
+	unsigned long flags;
 	int num_eqes = 0;
 
 	dev = eq->dev;
 	eqt = dev->priv.eq_table;
 
+	mlx5_eq_async_int_lock(eq_async, &flags);
+
 	eqe = next_eqe_sw(eq);
 	if (!eqe)
 		goto out;
@@ -223,8 +249,19 @@ static int mlx5_eq_async_int(struct notifier_block *nb,
 
 out:
 	eq_update_ci(eq, 1);
+	mlx5_eq_async_int_unlock(eq_async, &flags);
 
-	return 0;
+	return unlikely(action == ASYNC_EQ_RECOVER) ? num_eqes : 0;
+}
+
+void mlx5_cmd_eq_recover(struct mlx5_core_dev *dev)
+{
+	struct mlx5_eq_async *eq = &dev->priv.eq_table->cmd_eq;
+	int eqes;
+
+	eqes = mlx5_eq_async_int(&eq->irq_nb, ASYNC_EQ_RECOVER, NULL);
+	if (eqes)
+		mlx5_core_warn(dev, "Recovered %d EQEs on cmd_eq\n", eqes);
 }
 
 static void init_eq_buf(struct mlx5_eq *eq)
@@ -569,6 +606,7 @@ setup_async_eq(struct mlx5_core_dev *dev, struct mlx5_eq_async *eq,
 	int err;
 
 	eq->irq_nb.notifier_call = mlx5_eq_async_int;
+	spin_lock_init(&eq->lock);
 
 	err = create_async_eq(dev, &eq->core, param);
 	if (err) {