net/mlx5: Delay events till mlx5 interface's add complete for pci resume

mlx5_ib_add is called during mlx5_pci_resume after a pci error.
Before mlx5_ib_add completes, there are multiple events which trigger
function mlx5_ib_event. This cause kernel panic because mlx5_ib_event
accesses unitialized resources.

The fix is to extend Erez Shitrit's patch <97834eba>
("net/mlx5: Delay events till ib registration ends") to cover
the pci resume code path.

Trace:
mlx5_core 0001:01:00.6: mlx5_pci_resume was called
mlx5_core 0001:01:00.6: firmware version: 16.20.1011
mlx5_core 0001:01:00.6: mlx5_attach_interface:164:(pid 779):
mlx5_ib_event:2996:(pid 34777): warning: event on port 1
mlx5_ib_event:2996:(pid 34782): warning: event on port 1
Unable to handle kernel paging request for data at address 0x0001c104
Faulting instruction address: 0xd000000008f411fc
Oops: Kernel access of bad area, sig: 11 [#1]
...
...
Call Trace:
[c000000fff77bb70] [d000000008f4119c] mlx5_ib_event+0x64/0x470 [mlx5_ib] (unreliable)
[c000000fff77bc60] [d000000008e67130] mlx5_core_event+0xb8/0x210 [mlx5_core]
[c000000fff77bd10] [d000000008e4bd00] mlx5_eq_int+0x528/0x860[mlx5_core]

Fixes: 97834eba ("net/mlx5: Delay events till ib registration ends")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

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

@@ -77,35 +77,41 @@ static void add_delayed_event(struct mlx5_priv *priv,
 	list_add_tail(&delayed_event->list, &priv->waiting_events_list);
 }
 
-static void fire_delayed_event_locked(struct mlx5_device_context *dev_ctx,
-				      struct mlx5_core_dev *dev,
+static void delayed_event_release(struct mlx5_device_context *dev_ctx,
 				  struct mlx5_priv *priv)
 {
+	struct mlx5_core_dev *dev = container_of(priv, struct mlx5_core_dev, priv);
 	struct mlx5_delayed_event *de;
 	struct mlx5_delayed_event *n;
+	struct list_head temp;
 
-	/* stop delaying events */
-	priv->is_accum_events = false;
+	INIT_LIST_HEAD(&temp);
+
+	spin_lock_irq(&priv->ctx_lock);
 
-	/* fire all accumulated events before new event comes */
-	list_for_each_entry_safe(de, n, &priv->waiting_events_list, list) {
+	priv->is_accum_events = false;
+	list_splice_init(&priv->waiting_events_list, &temp);
+	if (!dev_ctx->context)
+		goto out;
+	list_for_each_entry_safe(de, n, &priv->waiting_events_list, list)
 		dev_ctx->intf->event(dev, dev_ctx->context, de->event, de->param);
+
+out:
+	spin_unlock_irq(&priv->ctx_lock);
+
+	list_for_each_entry_safe(de, n, &temp, list) {
 		list_del(&de->list);
 		kfree(de);
 	}
 }
 
-static void cleanup_delayed_evets(struct mlx5_priv *priv)
+/* accumulating events that can come after mlx5_ib calls to
+ * ib_register_device, till adding that interface to the events list.
+ */
+static void delayed_event_start(struct mlx5_priv *priv)
 {
-	struct mlx5_delayed_event *de;
-	struct mlx5_delayed_event *n;
-
 	spin_lock_irq(&priv->ctx_lock);
-	priv->is_accum_events = false;
-	list_for_each_entry_safe(de, n, &priv->waiting_events_list, list) {
-		list_del(&de->list);
-		kfree(de);
-	}
+	priv->is_accum_events = true;
 	spin_unlock_irq(&priv->ctx_lock);
 }
 
@@ -122,11 +128,8 @@ void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 		return;
 
 	dev_ctx->intf = intf;
-	/* accumulating events that can come after mlx5_ib calls to
-	 * ib_register_device, till adding that interface to the events list.
-	 */
 
-	priv->is_accum_events = true;
+	delayed_event_start(priv);
 
 	dev_ctx->context = intf->add(dev);
 	set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
@@ -137,8 +140,6 @@ void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 		spin_lock_irq(&priv->ctx_lock);
 		list_add_tail(&dev_ctx->list, &priv->ctx_list);
 
-		fire_delayed_event_locked(dev_ctx, dev, priv);
-
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 		if (dev_ctx->intf->pfault) {
 			if (priv->pfault) {
@@ -150,11 +151,12 @@ void mlx5_add_device(struct mlx5_interface *intf, struct mlx5_priv *priv)
 		}
 #endif
 		spin_unlock_irq(&priv->ctx_lock);
-	} else {
-		kfree(dev_ctx);
-		 /* delete all accumulated events */
-		cleanup_delayed_evets(priv);
 	}
+
+	delayed_event_release(dev_ctx, priv);
+
+	if (!dev_ctx->context)
+		kfree(dev_ctx);
 }
 
 static struct mlx5_device_context *mlx5_get_device(struct mlx5_interface *intf,
@@ -205,17 +207,21 @@ static void mlx5_attach_interface(struct mlx5_interface *intf, struct mlx5_priv
 	if (!dev_ctx)
 		return;
 
+	delayed_event_start(priv);
 	if (intf->attach) {
 		if (test_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state))
-			return;
+			goto out;
 		intf->attach(dev, dev_ctx->context);
 		set_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state);
 	} else {
 		if (test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state))
-			return;
+			goto out;
 		dev_ctx->context = intf->add(dev);
 		set_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state);
 	}
+
+out:
+	delayed_event_release(dev_ctx, priv);
 }
 
 void mlx5_attach_device(struct mlx5_core_dev *dev)
@@ -414,8 +420,14 @@ void mlx5_core_event(struct mlx5_core_dev *dev, enum mlx5_dev_event event,
 	if (priv->is_accum_events)
 		add_delayed_event(priv, dev, event, param);
 
+	/* After mlx5_detach_device, the dev_ctx->intf is still set and dev_ctx is
+	 * still in priv->ctx_list. In this case, only notify the dev_ctx if its
+	 * ADDED or ATTACHED bit are set.
+	 */
 	list_for_each_entry(dev_ctx, &priv->ctx_list, list)
-		if (dev_ctx->intf->event)
+		if (dev_ctx->intf->event &&
+		    (test_bit(MLX5_INTERFACE_ADDED, &dev_ctx->state) ||
+		     test_bit(MLX5_INTERFACE_ATTACHED, &dev_ctx->state)))
 			dev_ctx->intf->event(dev, dev_ctx->context, event, param);
 
 	spin_unlock_irqrestore(&priv->ctx_lock, flags);