sfc: Replace stats_enabled flag with a disable count

Currently we use a spin-lock to serialise statistics fetches and also
to inhibit them for short periods of time, plus a flag to
enable/disable statistics fetches for longer periods of time, during
online reset.  This was apparently insufficient to deal with the several
reasons for stats being disabled.

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

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index b0e5308..ab0e09b 100644 (file)
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -685,7 +685,7 @@ static int efx_init_port(struct efx_nic *efx)
        efx->mac_op->reconfigure(efx);
 
        efx->port_initialized = true;
-       efx->stats_enabled = true;
+       efx_stats_enable(efx);
        return 0;
 
 fail:
@@ -734,6 +734,7 @@ 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;
 
@@ -1360,6 +1361,20 @@ 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)
 {
@@ -1368,12 +1383,12 @@ static struct net_device_stats *efx_net_stats(struct net_device *net_dev)
        struct net_device_stats *stats = &net_dev->stats;
 
        /* Update stats if possible, but do not wait if another thread
-        * is updating them (or resetting the NIC); slightly stale
-        * stats are acceptable.
+        * 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_enabled) {
+       if (!efx->stats_disable_count) {
                efx->mac_op->update_stats(efx);
                falcon_update_nic_stats(efx);
        }
@@ -1626,12 +1641,7 @@ void efx_reset_down(struct efx_nic *efx, enum reset_type method,
 {
        EFX_ASSERT_RESET_SERIALISED(efx);
 
-       /* The net_dev->get_stats handler is quite slow, and will fail
-        * if a fetch is pending over reset. Serialise against it. */
-       spin_lock(&efx->stats_lock);
-       efx->stats_enabled = false;
-       spin_unlock(&efx->stats_lock);
-
+       efx_stats_disable(efx);
        efx_stop_all(efx);
        mutex_lock(&efx->mac_lock);
        mutex_lock(&efx->spi_lock);
@@ -1682,7 +1692,7 @@ int efx_reset_up(struct efx_nic *efx, enum reset_type method,
 
        if (ok) {
                efx_start_all(efx);
-               efx->stats_enabled = true;
+               efx_stats_enable(efx);
        }
        return rc;
 }
@@ -1888,6 +1898,7 @@ 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;

diff --git a/drivers/net/sfc/efx.h b/drivers/net/sfc/efx.h
index ac20158..55d0f13 100644 (file)
--- a/drivers/net/sfc/efx.h
+++ b/drivers/net/sfc/efx.h
@@ -36,6 +36,8 @@ extern void efx_process_channel_now(struct efx_channel *channel);
 extern void efx_flush_queues(struct efx_nic *efx);
 
 /* Ports */
+extern void efx_stats_disable(struct efx_nic *efx);
+extern void efx_stats_enable(struct efx_nic *efx);
 extern void efx_reconfigure_port(struct efx_nic *efx);
 extern void __efx_reconfigure_port(struct efx_nic *efx);
 

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index d9412f8..d5378e6 100644 (file)
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -1883,7 +1883,7 @@ static int falcon_reset_macs(struct efx_nic *efx)
 
        /* MAC stats will fail whilst the TX fifo is draining. Serialise
         * the drain sequence with the statistics fetch */
-       spin_lock(&efx->stats_lock);
+       efx_stats_disable(efx);
 
        falcon_read(efx, &reg, MAC0_CTRL_REG_KER);
        EFX_SET_OWORD_FIELD(reg, TXFIFO_DRAIN_EN_B0, 1);
@@ -1913,7 +1913,7 @@ static int falcon_reset_macs(struct efx_nic *efx)
                udelay(10);
        }
 
-       spin_unlock(&efx->stats_lock);
+       efx_stats_enable(efx);
 
        /* If we've reset the EM block and the link is up, then
         * we'll have to kick the XAUI link so the PHY can recover */
@@ -2273,6 +2273,10 @@ int falcon_switch_mac(struct efx_nic *efx)
        struct efx_mac_operations *old_mac_op = efx->mac_op;
        efx_oword_t nic_stat;
        unsigned strap_val;
+       int rc = 0;
+
+       /* Don't try to fetch MAC stats while we're switching MACs */
+       efx_stats_disable(efx);
 
        /* Internal loopbacks override the phy speed setting */
        if (efx->loopback_mode == LOOPBACK_GMAC) {
@@ -2302,13 +2306,16 @@ int falcon_switch_mac(struct efx_nic *efx)
        }
 
        if (old_mac_op == efx->mac_op)
-               return 0;
+               goto out;
 
        EFX_LOG(efx, "selected %cMAC\n", EFX_IS10G(efx) ? 'X' : 'G');
        /* Not all macs support a mac-level link state */
        efx->mac_up = true;
 
-       return falcon_reset_macs(efx);
+       rc = falcon_reset_macs(efx);
+out:
+       efx_stats_enable(efx);
+       return rc;
 }
 
 /* This call is responsible for hooking in the MAC and PHY operations */

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 8eb411a..e019ad1 100644 (file)
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -754,8 +754,7 @@ union efx_multicast_hash {
  *     &struct net_device_stats.
  * @stats_buffer: DMA buffer for statistics
  * @stats_lock: Statistics update lock. Serialises statistics fetches
- * @stats_enabled: Temporarily disable statistics fetches.
- *     Serialised by @stats_lock
+ * @stats_disable_count: Nest count for disabling statistics fetches
  * @mac_op: MAC interface
  * @mac_address: Permanent MAC address
  * @phy_type: PHY type
@@ -837,7 +836,7 @@ struct efx_nic {
        struct efx_mac_stats mac_stats;
        struct efx_buffer stats_buffer;
        spinlock_t stats_lock;
-       bool stats_enabled;
+       unsigned int stats_disable_count;
 
        struct efx_mac_operations *mac_op;
        unsigned char mac_address[ETH_ALEN];

diff --git a/drivers/net/sfc/sfe4001.c b/drivers/net/sfc/sfe4001.c
index 853057e..cb25ae5 100644 (file)
--- a/drivers/net/sfc/sfe4001.c
+++ b/drivers/net/sfc/sfe4001.c
@@ -235,12 +235,18 @@ static ssize_t set_phy_flash_cfg(struct device *dev,
        } else if (efx->state != STATE_RUNNING || netif_running(efx->net_dev)) {
                err = -EBUSY;
        } else {
+               /* Reset the PHY, reconfigure the MAC and enable/disable
+                * MAC stats accordingly. */
                efx->phy_mode = new_mode;
+               if (new_mode & PHY_MODE_SPECIAL)
+                       efx_stats_disable(efx);
                if (efx->board_info.type == EFX_BOARD_SFE4001)
                        err = sfe4001_poweron(efx);
                else
                        err = sfn4111t_reset(efx);
                efx_reconfigure_port(efx);
+               if (!(new_mode & PHY_MODE_SPECIAL))
+                       efx_stats_enable(efx);
        }
        rtnl_unlock();
 
@@ -329,6 +335,11 @@ int sfe4001_init(struct efx_nic *efx)
        efx->board_info.monitor = sfe4001_check_hw;
        efx->board_info.fini = sfe4001_fini;
 
+       if (efx->phy_mode & PHY_MODE_SPECIAL) {
+               /* PHY won't generate a 156.25 MHz clock and MAC stats fetch
+                * will fail. */
+               efx_stats_disable(efx);
+       }
        rc = sfe4001_poweron(efx);
        if (rc)
                goto fail_ioexp;
@@ -405,8 +416,10 @@ int sfn4111t_init(struct efx_nic *efx)
        if (rc)
                goto fail_hwmon;
 
-       if (efx->phy_mode & PHY_MODE_SPECIAL)
+       if (efx->phy_mode & PHY_MODE_SPECIAL) {
+               efx_stats_disable(efx);
                sfn4111t_reset(efx);
+       }
 
        return 0;
 

diff --git a/drivers/net/sfc/tenxpress.c b/drivers/net/sfc/tenxpress.c
index 412d209..f0efd24 100644 (file)
--- a/drivers/net/sfc/tenxpress.c
+++ b/drivers/net/sfc/tenxpress.c
@@ -370,8 +370,8 @@ static int tenxpress_special_reset(struct efx_nic *efx)
 
        /* The XGMAC clock is driven from the SFC7101/SFT9001 312MHz clock, so
         * a special software reset can glitch the XGMAC sufficiently for stats
-        * requests to fail. Since we don't often special_reset, just lock. */
-       spin_lock(&efx->stats_lock);
+        * requests to fail. */
+       efx_stats_disable(efx);
 
        /* Initiate reset */
        reg = mdio_clause45_read(efx, efx->mii.phy_id,
@@ -386,17 +386,17 @@ static int tenxpress_special_reset(struct efx_nic *efx)
        rc = mdio_clause45_wait_reset_mmds(efx,
                                           TENXPRESS_REQUIRED_DEVS);
        if (rc < 0)
-               goto unlock;
+               goto out;
 
        /* Try and reconfigure the device */
        rc = tenxpress_init(efx);
        if (rc < 0)
-               goto unlock;
+               goto out;
 
        /* Wait for the XGXS state machine to churn */
        mdelay(10);
-unlock:
-       spin_unlock(&efx->stats_lock);
+out:
+       efx_stats_enable(efx);
        return rc;
 }