i40evf: fix crash when changing ring sizes

i40evf_set_ringparam was broken in several ways. First, it only changed
the size of the first ring, and second, changing the ring size would
often result in a panic because it would change the count before
deallocating resources, causing the driver to either free nonexistent
buffers, or leak leftover buffers.

Fix this by storing the descriptor count in the adapter structure, and
updating the count for each ring each time we allocate them. This
ensures that we always free the right size ring, and always end up with
the requested count when the device is (re)opened.

Change-ID: I298396cd3d452ba8509d9f2d33a93f25868a9a55
Signed-off-by: Mitch Williams <[e-mail]>
Signed-off-by: Jeff Kirsher <[e-mail]>

drivers/net/ethernet/intel/i40evf/i40evf.h

···
 	struct i40e_ring *tx_rings[I40E_MAX_VSI_QP];
 	u32 tx_timeout_count;
 	struct list_head mac_filter_list;
+	u32 tx_desc_count;
 
 	/* RX */
 	struct i40e_ring *rx_rings[I40E_MAX_VSI_QP];
 	u64 hw_csum_rx_error;
+	u32 rx_desc_count;
 	int num_msix_vectors;
 	struct msix_entry *msix_entries;
 

drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c

···
 				  struct ethtool_ringparam *ring)
 {
 	struct i40evf_adapter *adapter = netdev_priv(netdev);
-	struct i40e_ring *tx_ring = adapter->tx_rings[0];
-	struct i40e_ring *rx_ring = adapter->rx_rings[0];
 
 	ring->rx_max_pending = I40EVF_MAX_RXD;
 	ring->tx_max_pending = I40EVF_MAX_TXD;
-	ring->rx_pending = rx_ring->count;
-	ring->tx_pending = tx_ring->count;
+	ring->rx_pending = adapter->rx_desc_count;
+	ring->tx_pending = adapter->tx_desc_count;
 }
 
 /**
···
 {
 	struct i40evf_adapter *adapter = netdev_priv(netdev);
 	u32 new_rx_count, new_tx_count;
-	int i;
 
 	if ((ring->rx_mini_pending) || (ring->rx_jumbo_pending))
 		return -EINVAL;
···
 	new_rx_count = ALIGN(new_rx_count, I40EVF_REQ_DESCRIPTOR_MULTIPLE);
 
 	/* if nothing to do return success */
-	if ((new_tx_count == adapter->tx_rings[0]->count) &&
-	    (new_rx_count == adapter->rx_rings[0]->count))
+	if ((new_tx_count == adapter->tx_desc_count) &&
+	    (new_rx_count == adapter->rx_desc_count))
 		return 0;
 
-	for (i = 0; i < adapter->vsi_res->num_queue_pairs; i++) {
-		adapter->tx_rings[0]->count = new_tx_count;
-		adapter->rx_rings[0]->count = new_rx_count;
-	}
+	adapter->tx_desc_count = new_tx_count;
+	adapter->rx_desc_count = new_rx_count;
 
 	if (netif_running(netdev))
 		i40evf_reinit_locked(adapter);
+
 	return 0;
 }
 

drivers/net/ethernet/intel/i40evf/i40evf_main.c

···
 		tx_ring->queue_index = i;
 		tx_ring->netdev = adapter->netdev;
 		tx_ring->dev = &adapter->pdev->dev;
-		tx_ring->count = I40EVF_DEFAULT_TXD;
+		tx_ring->count = adapter->tx_desc_count;
 		adapter->tx_rings[i] = tx_ring;
 
 		rx_ring = &tx_ring[1];
 		rx_ring->queue_index = i;
 		rx_ring->netdev = adapter->netdev;
 		rx_ring->dev = &adapter->pdev->dev;
-		rx_ring->count = I40EVF_DEFAULT_RXD;
+		rx_ring->count = adapter->rx_desc_count;
 		adapter->rx_rings[i] = rx_ring;
 	}
 
···
 	int i, err = 0;
 
 	for (i = 0; i < adapter->vsi_res->num_queue_pairs; i++) {
+		adapter->tx_rings[i]->count = adapter->tx_desc_count;
 		err = i40evf_setup_tx_descriptors(adapter->tx_rings[i]);
 		if (!err)
 			continue;
···
 	int i, err = 0;
 
 	for (i = 0; i < adapter->vsi_res->num_queue_pairs; i++) {
+		adapter->rx_rings[i]->count = adapter->rx_desc_count;
 		err = i40evf_setup_rx_descriptors(adapter->rx_rings[i]);
 		if (!err)
 			continue;
···
 	adapter->watchdog_timer.data = (unsigned long)adapter;
 	mod_timer(&adapter->watchdog_timer, jiffies + 1);
 
+	adapter->tx_desc_count = I40EVF_DEFAULT_TXD;
+	adapter->rx_desc_count = I40EVF_DEFAULT_RXD;
 	err = i40evf_init_interrupt_scheme(adapter);
 	if (err)
 		goto err_sw_init;