net/mlx4_core: Do not BUG_ON during reset when PCI is offline

commit 22e3817e upstream.

The PCI channel could go offline during reset due to EEH.  Don't bug on in
this case, the error is recoverable.

Fixes: f6bc11e4 ('net/mlx4_core: Enhance the catas flow to support device reset')
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/net/ethernet/mellanox/mlx4/catas.c

@@ -182,10 +182,17 @@ void mlx4_enter_error_state(struct mlx4_dev_persistent *persist)
 		err = mlx4_reset_slave(dev);
 	else
 		err = mlx4_reset_master(dev);
-	BUG_ON(err != 0);
 
+	if (!err) {
+		mlx4_err(dev, "device was reset successfully\n");
+	} else {
+		/* EEH could have disabled the PCI channel during reset. That's
+		 * recoverable and the PCI error flow will handle it.
+		 */
+		if (!pci_channel_offline(dev->persist->pdev))
+			BUG_ON(1);
+	}
 	dev->persist->state |= MLX4_DEVICE_STATE_INTERNAL_ERROR;
-	mlx4_err(dev, "device was reset successfully\n");
 	mutex_unlock(&persist->device_state_mutex);
 
 	/* At that step HW was already reset, now notify clients */