net: fec: add locking for MDIO bus access

Both fec_restart() and fec_stop() both perform a reset of the FEC.  This
reset can result in an in-process MDIO transfer being terminated, which
can lead to the MDIO read/write functions timing out.  Add some locking
to prevent this occuring.

We can't use a spinlock for this as the MDIO accessor functions use
wait_for_completion_timeout(), which sleeps.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 29 insertions, 1 deletions

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index f786485acf63..f67e83967a15 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1075,12 +1075,14 @@ static void fec_enet_timeout_work(struct work_struct *work)
 
 	rtnl_lock();
 	if (netif_device_present(ndev) || netif_running(ndev)) {
+		mutex_lock(&fep->mutex);
 		napi_disable(&fep->napi);
 		netif_tx_lock_bh(ndev);
 		fec_restart(ndev);
 		netif_wake_queue(ndev);
 		netif_tx_unlock_bh(ndev);
 		napi_enable(&fep->napi);
+		mutex_unlock(&fep->mutex);
 	}
 	rtnl_unlock();
 }
@@ -1568,20 +1570,24 @@ static void fec_enet_adjust_link(struct net_device *ndev)
 
 		/* if any of the above changed restart the FEC */
 		if (status_change) {
+			mutex_lock(&fep->mutex);
 			napi_disable(&fep->napi);
 			netif_tx_lock_bh(ndev);
 			fec_restart(ndev);
 			netif_wake_queue(ndev);
 			netif_tx_unlock_bh(ndev);
 			napi_enable(&fep->napi);
+			mutex_unlock(&fep->mutex);
 		}
 	} else {
 		if (fep->link) {
+			mutex_lock(&fep->mutex);
 			napi_disable(&fep->napi);
 			netif_tx_lock_bh(ndev);
 			fec_stop(ndev);
 			netif_tx_unlock_bh(ndev);
 			napi_enable(&fep->napi);
+			mutex_unlock(&fep->mutex);
 			fep->link = phy_dev->link;
 			status_change = 1;
 		}
@@ -1594,15 +1600,23 @@ static void fec_enet_adjust_link(struct net_device *ndev)
 static unsigned long fec_enet_mdio_op(struct fec_enet_private *fep,
 	unsigned data)
 {
+	unsigned long time_left;
+
 	fep->mii_timeout = 0;
 	init_completion(&fep->mdio_done);
 
+	mutex_lock(&fep->mutex);
+
 	/* start operation */
 	writel(data, fep->hwp + FEC_MII_DATA);
 
 	/* wait for end of transfer */
-	return wait_for_completion_timeout(&fep->mdio_done,
+	time_left = wait_for_completion_timeout(&fep->mdio_done,
 			usecs_to_jiffies(FEC_MII_TIMEOUT));
+
+	mutex_unlock(&fep->mutex);
+
+	return time_left;
 }
 
 static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
@@ -2039,6 +2053,7 @@ static int fec_enet_set_pauseparam(struct net_device *ndev,
 			fep->pause_mode = fep->pause_flag;
 
 			if (netif_running(ndev)) {
+				mutex_lock(&fep->mutex);
 				napi_disable(&fep->napi);
 				netif_tx_lock_bh(ndev);
 				fec_stop(ndev);
@@ -2046,6 +2061,7 @@ static int fec_enet_set_pauseparam(struct net_device *ndev,
 				netif_wake_queue(ndev);
 				netif_tx_unlock_bh(ndev);
 				napi_enable(&fep->napi);
+				mutex_unlock(&fep->mutex);
 			}
 		}
 	}
@@ -2318,7 +2334,9 @@ fec_enet_open(struct net_device *ndev)
 		return ret;
 	}
 
+	mutex_lock(&fep->mutex);
 	fec_restart(ndev);
+	mutex_unlock(&fep->mutex);
 	napi_enable(&fep->napi);
 	phy_start(fep->phy_dev);
 	netif_start_queue(ndev);
@@ -2335,7 +2353,9 @@ fec_enet_close(struct net_device *ndev)
 	if (netif_device_present(ndev)) {
 		napi_disable(&fep->napi);
 		netif_tx_disable(ndev);
+		mutex_lock(&fep->mutex);
 		fec_stop(ndev);
+		mutex_unlock(&fep->mutex);
 	}
 
 	phy_disconnect(fep->phy_dev);
@@ -2492,6 +2512,7 @@ static int fec_set_features(struct net_device *netdev,
 
 	/* Quiesce the device if necessary */
 	if (netif_running(netdev) && changed & FEATURES_NEED_QUIESCE) {
+		mutex_lock(&fep->mutex);
 		napi_disable(&fep->napi);
 		netif_tx_lock_bh(netdev);
 		fec_stop(netdev);
@@ -2524,6 +2545,7 @@ static int fec_set_features(struct net_device *netdev,
 		netif_wake_queue(netdev);
 		netif_tx_unlock_bh(netdev);
 		napi_enable(&fep->napi);
+		mutex_unlock(&fep->mutex);
 	}
 
 	return 0;
@@ -2710,6 +2732,8 @@ fec_probe(struct platform_device *pdev)
 	/* setup board info structure */
 	fep = netdev_priv(ndev);
 
+	mutex_init(&fep->mutex);
+
 #if !defined(CONFIG_M5272)
 	/* default enable pause frame auto negotiation */
 	if (pdev->id_entry &&
@@ -2895,7 +2919,9 @@ static int __maybe_unused fec_suspend(struct device *dev)
 		netif_tx_lock_bh(ndev);
 		netif_device_detach(ndev);
 		netif_tx_unlock_bh(ndev);
+		mutex_lock(&fep->mutex);
 		fec_stop(ndev);
+		mutex_unlock(&fep->mutex);
 	}
 	rtnl_unlock();
 
@@ -2927,7 +2953,9 @@ static int __maybe_unused fec_resume(struct device *dev)
 
 	rtnl_lock();
 	if (netif_running(ndev)) {
+		mutex_lock(&fep->mutex);
 		fec_restart(ndev);
+		mutex_unlock(&fep->mutex);
 		netif_tx_lock_bh(ndev);
 		netif_device_attach(ndev);
 		netif_tx_unlock_bh(ndev);