drivers/net: fixed drivers that support netpoll use ndo_start_xmit()

The NETPOLL API requires that interrupts remain disabled in
netpoll_send_skb(). The use of "A functions set" in the NETPOLL API
callbacks causes the interrupts to get enabled and can lead to kernel
instability.

The solution is to use "B functions set" to prevent the irqs from
getting enabled while in netpoll_send_skb().

A functions set:
local_irq_disable()/local_irq_enable()
spin_lock_irq()/spin_unlock_irq()
spin_trylock_irq()/spin_unlock_irq()

B functions set:
local_irq_save()/local_irq_restore()
spin_lock_irqsave()/spin_unlock_irqrestore()
spin_trylock_irqsave()/spin_unlock_irqrestore()

Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/net/fec_mpc52xx.c b/drivers/net/fec_mpc52xx.c
index cc786333d95c..c40113f58963 100644
--- a/drivers/net/fec_mpc52xx.c
+++ b/drivers/net/fec_mpc52xx.c
@@ -309,6 +309,7 @@ static int mpc52xx_fec_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct mpc52xx_fec_priv *priv = netdev_priv(dev);
         struct bcom_fec_bd *bd;
+        unsigned long flags;
 
         if (bcom_queue_full(priv->tx_dmatsk)) {
                 if (net_ratelimit())
@@ -316,7 +317,7 @@ static int mpc52xx_fec_start_xmit(struct sk_buff *skb, struct net_device *dev)
                 return NETDEV_TX_BUSY;
         }
 
-        spin_lock_irq(&priv->lock);
+        spin_lock_irqsave(&priv->lock, flags);
         dev->trans_start = jiffies;
 
         bd = (struct bcom_fec_bd *)
@@ -332,7 +333,7 @@ static int mpc52xx_fec_start_xmit(struct sk_buff *skb, struct net_device *dev)
                 netif_stop_queue(dev);
         }
 
-        spin_unlock_irq(&priv->lock);
+        spin_unlock_irqrestore(&priv->lock, flags);
 
         return NETDEV_TX_OK;
 }