sfc: do not device_attach if a reset is pending

commit 9c568fd8 upstream.

efx_start_all can return without initialising queues as a reset is pending.
 This means that when netif_device_attach is called, the kernel can start
 sending traffic without having an initialised TX queue to send to.
This patch avoids this by not calling netif_device_attach if there is a
 pending reset.

Fixes: e283546c ("sfc:On MCDI timeout, issue an FLR (and mark MCDI to fail-fast)")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16:
 - Drop changes in ef10.c and ef10_sriov.c
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/ethernet/sfc/efx.c

@@ -833,7 +833,7 @@ efx_realloc_channels(struct efx_nic *efx, u32 rxq_entries, u32 txq_entries)
 		efx_schedule_reset(efx, RESET_TYPE_DISABLE);
 	} else {
 		efx_start_all(efx);
-		netif_device_attach(efx->net_dev);
+		efx_device_attach_if_not_resetting(efx);
 	}
 	return rc;
 
@@ -2036,6 +2036,8 @@ static int efx_net_open(struct net_device *net_dev)
 	efx_link_status_changed(efx);
 
 	efx_start_all(efx);
+	if (efx->state == STATE_DISABLED || efx->reset_pending)
+		netif_device_detach(efx->net_dev);
 	efx_selftest_async_start(efx);
 	return 0;
 }
@@ -2106,7 +2108,7 @@ static int efx_change_mtu(struct net_device *net_dev, int new_mtu)
 	mutex_unlock(&efx->mac_lock);
 
 	efx_start_all(efx);
-	netif_device_attach(efx->net_dev);
+	efx_device_attach_if_not_resetting(efx);
 	return 0;
 }
 
@@ -2455,7 +2457,7 @@ int efx_reset(struct efx_nic *efx, enum reset_type method)
 		efx->state = STATE_DISABLED;
 	} else {
 		netif_dbg(efx, drv, efx->net_dev, "reset complete\n");
-		netif_device_attach(efx->net_dev);
+		efx_device_attach_if_not_resetting(efx);
 	}
 	return rc;
 }
@@ -3035,7 +3037,7 @@ static int efx_pm_thaw(struct device *dev)
 
 		efx_start_all(efx);
 
-		netif_device_attach(efx->net_dev);
+		efx_device_attach_if_not_resetting(efx);
 
 		efx->state = STATE_READY;
 

drivers/net/ethernet/sfc/efx.h

@@ -247,4 +247,10 @@ static inline void efx_device_detach_sync(struct efx_nic *efx)
 	netif_tx_unlock_bh(dev);
 }
 
+static inline void efx_device_attach_if_not_resetting(struct efx_nic *efx)
+{
+	if ((efx->state != STATE_DISABLED) && !efx->reset_pending)
+		netif_device_attach(efx->net_dev);
+}
+
 #endif /* EFX_EFX_H */

drivers/net/ethernet/sfc/selftest.c

@@ -749,7 +749,7 @@ int efx_selftest(struct efx_nic *efx, struct efx_self_tests *tests,
 	__efx_reconfigure_port(efx);
 	mutex_unlock(&efx->mac_lock);
 
-	netif_device_attach(efx->net_dev);
+	efx_device_attach_if_not_resetting(efx);
 
 	return rc_test;
 }