sfc: Split MAC stats DMA initiation and completion

From: Steve Hodgson <shodgson@solarflare.com>

Currently we initiate MAC stats DMA and busy-wait for completion when
stats are requested.  We can improve on this with a periodic timer to
initiate and poll for stats, and opportunistically poll when stats are
requested.

Since efx_nic::stats_disable_count and efx_stats_{disable,enable}()
are Falcon-specific, rename them and move them accordingly.

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

1 files changed, 13 insertions, 35 deletions

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 155aa1cca366..41ca5dbb4c44 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -637,6 +637,7 @@ void __efx_reconfigure_port(struct efx_nic *efx)
                 netif_addr_unlock_bh(efx->net_dev);
         }
 
+        falcon_stop_nic_stats(efx);
         falcon_deconfigure_mac_wrapper(efx);
 
         /* Reconfigure the PHY, disabling transmit in mac level loopback. */
@@ -651,6 +652,8 @@ void __efx_reconfigure_port(struct efx_nic *efx)
 
         efx->mac_op->reconfigure(efx);
 
+        falcon_start_nic_stats(efx);
+
         /* Inform kernel of loss/gain of carrier */
         efx_link_status_changed(efx);
         return;
@@ -749,7 +752,6 @@ static int efx_init_port(struct efx_nic *efx)
         efx->mac_op->reconfigure(efx);
 
         efx->port_initialized = true;
-        efx_stats_enable(efx);
 
         mutex_unlock(&efx->mac_lock);
         return 0;
@@ -802,7 +804,6 @@ static void efx_fini_port(struct efx_nic *efx)
         if (!efx->port_initialized)
                 return;
 
-        efx_stats_disable(efx);
         efx->phy_op->fini(efx);
         efx->port_initialized = false;
 
@@ -1158,6 +1159,8 @@ static void efx_start_all(struct efx_nic *efx)
         if (efx->state == STATE_RUNNING)
                 queue_delayed_work(efx->workqueue, &efx->monitor_work,
                                    efx_monitor_interval);
+
+        falcon_start_nic_stats(efx);
 }
 
 /* Flush all delayed work. Should only be called when no more delayed work
@@ -1195,6 +1198,8 @@ static void efx_stop_all(struct efx_nic *efx)
         if (!efx->port_enabled)
                 return;
 
+        falcon_stop_nic_stats(efx);
+
         /* Disable interrupts and wait for ISR to complete */
         falcon_disable_interrupts(efx);
         if (efx->legacy_irq)
@@ -1438,20 +1443,6 @@ static int efx_net_stop(struct net_device *net_dev)
         return 0;
 }
 
-void efx_stats_disable(struct efx_nic *efx)
-{
-        spin_lock(&efx->stats_lock);
-        ++efx->stats_disable_count;
-        spin_unlock(&efx->stats_lock);
-}
-
-void efx_stats_enable(struct efx_nic *efx)
-{
-        spin_lock(&efx->stats_lock);
-        --efx->stats_disable_count;
-        spin_unlock(&efx->stats_lock);
-}
-
 /* Context: process, dev_base_lock or RTNL held, non-blocking. */
 static struct net_device_stats *efx_net_stats(struct net_device *net_dev)
 {
@@ -1459,17 +1450,9 @@ static struct net_device_stats *efx_net_stats(struct net_device *net_dev)
         struct efx_mac_stats *mac_stats = &efx->mac_stats;
         struct net_device_stats *stats = &net_dev->stats;
 
-        /* Update stats if possible, but do not wait if another thread
-         * is updating them or if MAC stats fetches are temporarily
-         * disabled; slightly stale stats are acceptable.
-         */
-        if (!spin_trylock(&efx->stats_lock))
-                return stats;
-        if (!efx->stats_disable_count) {
-                efx->mac_op->update_stats(efx);
-                falcon_update_nic_stats(efx);
-        }
-        spin_unlock(&efx->stats_lock);
+        spin_lock_bh(&efx->stats_lock);
+        falcon_update_nic_stats(efx);
+        spin_unlock_bh(&efx->stats_lock);
 
         stats->rx_packets = mac_stats->rx_packets;
         stats->tx_packets = mac_stats->tx_packets;
@@ -1726,7 +1709,6 @@ void efx_reset_down(struct efx_nic *efx, enum reset_type method,
 {
         EFX_ASSERT_RESET_SERIALISED(efx);
 
-        efx_stats_disable(efx);
         efx_stop_all(efx);
         mutex_lock(&efx->mac_lock);
         mutex_lock(&efx->spi_lock);
@@ -1776,10 +1758,8 @@ int efx_reset_up(struct efx_nic *efx, enum reset_type method,
         mutex_unlock(&efx->spi_lock);
         mutex_unlock(&efx->mac_lock);
 
-        if (ok) {
+        if (ok)
                 efx_start_all(efx);
-                efx_stats_enable(efx);
-        }
         return rc;
 }
 
@@ -1977,7 +1957,6 @@ static int efx_init_struct(struct efx_nic *efx, struct efx_nic_type *type,
         efx->rx_checksum_enabled = true;
         spin_lock_init(&efx->netif_stop_lock);
         spin_lock_init(&efx->stats_lock);
-        efx->stats_disable_count = 1;
         mutex_init(&efx->mac_lock);
         efx->mac_op = &efx_dummy_mac_operations;
         efx->phy_op = &efx_dummy_phy_operations;
@@ -2219,9 +2198,8 @@ static int __devinit efx_pci_probe(struct pci_dev *pci_dev,
                 goto fail4;
         }
 
-        /* Switch to the running state before we expose the device to
-         * the OS.  This is to ensure that the initial gathering of
-         * MAC stats succeeds. */
+        /* Switch to the running state before we expose the device to the OS,
+         * so that dev_open()|efx_start_all() will actually start the device */
         efx->state = STATE_RUNNING;
 
         rc = efx_register_netdev(efx);