sfc: Allow changing the DMA ring sizes dynamically via ethtool

This requires some reorganisation of channel setup and teardown to
ensure that we can always roll-back a failed change.

Based on work by Steve Hodgson <shodgson@solarflare.com>

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/net/sfc/ethtool.c b/drivers/net/sfc/ethtool.c
index b9291db023bb..7f735d804801 100644
--- a/drivers/net/sfc/ethtool.c
+++ b/drivers/net/sfc/ethtool.c
@@ -742,6 +742,42 @@ static int efx_ethtool_set_coalesce(struct net_device *net_dev,
         return 0;
 }
 
+static void efx_ethtool_get_ringparam(struct net_device *net_dev,
+                                      struct ethtool_ringparam *ring)
+{
+        struct efx_nic *efx = netdev_priv(net_dev);
+
+        ring->rx_max_pending = EFX_MAX_DMAQ_SIZE;
+        ring->tx_max_pending = EFX_MAX_DMAQ_SIZE;
+        ring->rx_mini_max_pending = 0;
+        ring->rx_jumbo_max_pending = 0;
+        ring->rx_pending = efx->rxq_entries;
+        ring->tx_pending = efx->txq_entries;
+        ring->rx_mini_pending = 0;
+        ring->rx_jumbo_pending = 0;
+}
+
+static int efx_ethtool_set_ringparam(struct net_device *net_dev,
+                                     struct ethtool_ringparam *ring)
+{
+        struct efx_nic *efx = netdev_priv(net_dev);
+
+        if (ring->rx_mini_pending || ring->rx_jumbo_pending ||
+            ring->rx_pending > EFX_MAX_DMAQ_SIZE ||
+            ring->tx_pending > EFX_MAX_DMAQ_SIZE)
+                return -EINVAL;
+
+        if (ring->rx_pending < EFX_MIN_RING_SIZE ||
+            ring->tx_pending < EFX_MIN_RING_SIZE) {
+                netif_err(efx, drv, efx->net_dev,
+                          "TX and RX queues cannot be smaller than %ld\n",
+                          EFX_MIN_RING_SIZE);
+                return -EINVAL;
+        }
+
+        return efx_realloc_channels(efx, ring->rx_pending, ring->tx_pending);
+}
+
 static int efx_ethtool_set_pauseparam(struct net_device *net_dev,
                                       struct ethtool_pauseparam *pause)
 {
@@ -972,6 +1008,8 @@ const struct ethtool_ops efx_ethtool_ops = {
         .set_eeprom             = efx_ethtool_set_eeprom,
         .get_coalesce           = efx_ethtool_get_coalesce,
         .set_coalesce           = efx_ethtool_set_coalesce,
+        .get_ringparam          = efx_ethtool_get_ringparam,
+        .set_ringparam          = efx_ethtool_set_ringparam,
         .get_pauseparam         = efx_ethtool_get_pauseparam,
         .set_pauseparam         = efx_ethtool_set_pauseparam,
         .get_rx_csum            = efx_ethtool_get_rx_csum,