sky2: Avoid transmits during sky2_down()

This patch supersedes my previous patch "sky2: Avoid transmitting
during sky2_restart".

I have reworked the patch to avoid crashes during both sky2_restart()
and sky2_set_ringparam().

Without this patch, the sky2 driver can be crashed by doing:

# pktgen eth1 &    (transmit many packets on eth1)
# ethtool -G eth1 tx 510

I am aware you object to storing extra state, but I can't see a way
around this. Without remembering that we're restarting,
netif_wake_queue() is called in the ISR from sky2_tx_complete(), and
netif_tx_lock() is used in sky2_tx_done().  If anybody can see a way
around this, please let me know.

Signed-off-by: Mike McCormack <mikem@ring3k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 14 insertions, 1 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 3550c5dcd93c..0a551d8f5d95 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1488,6 +1488,8 @@ static int sky2_up(struct net_device *dev)
         sky2_set_vlan_mode(hw, port, sky2->vlgrp != NULL);
 #endif
 
+        sky2->restarting = 0;
+
         err = sky2_rx_start(sky2);
         if (err)
                 goto err_out;
@@ -1500,6 +1502,9 @@ static int sky2_up(struct net_device *dev)
 
         sky2_set_multicast(dev);
 
+        /* wake queue incase we are restarting */
+        netif_wake_queue(dev);
+
         if (netif_msg_ifup(sky2))
                 printk(KERN_INFO PFX "%s: enabling interface\n", dev->name);
         return 0;
@@ -1533,6 +1538,8 @@ static inline int tx_dist(unsigned tail, unsigned head)
 /* Number of list elements available for next tx */
 static inline int tx_avail(const struct sky2_port *sky2)
 {
+        if (unlikely(sky2->restarting))
+                return 0;
         return sky2->tx_pending - tx_dist(sky2->tx_cons, sky2->tx_prod);
 }
 
@@ -1818,6 +1825,10 @@ static int sky2_down(struct net_device *dev)
         if (netif_msg_ifdown(sky2))
                 printk(KERN_INFO PFX "%s: disabling interface\n", dev->name);
 
+        /* explicitly shut off tx incase we're restarting */
+        sky2->restarting = 1;
+        netif_tx_disable(dev);
+
         /* Force flow control off */
         sky2_write8(hw, SK_REG(port, GMAC_CTRL), GMC_PAUSE_OFF);
 
@@ -2359,7 +2370,7 @@ static inline void sky2_tx_done(struct net_device *dev, u16 last)
 {
         struct sky2_port *sky2 = netdev_priv(dev);
 
-        if (netif_running(dev)) {
+        if (likely(netif_running(dev) && !sky2->restarting)) {
                 netif_tx_lock(dev);
                 sky2_tx_complete(sky2, last);
                 netif_tx_unlock(dev);
@@ -4283,6 +4294,7 @@ static __devinit struct net_device *sky2_init_netdev(struct sky2_hw *hw,
         spin_lock_init(&sky2->phy_lock);
         sky2->tx_pending = TX_DEF_PENDING;
         sky2->rx_pending = RX_DEF_PENDING;
+        sky2->restarting = 0;
 
         hw->dev[port] = dev;
 
diff --git a/drivers/net/sky2.h b/drivers/net/sky2.h
index b5549c9e5107..4486b066b43f 100644
--- a/drivers/net/sky2.h
+++ b/drivers/net/sky2.h
@@ -2051,6 +2051,7 @@ struct sky2_port {
         u8                   duplex;    /* DUPLEX_HALF, DUPLEX_FULL */
         u8                   rx_csum;
         u8                   wol;
+        u8                   restarting;
         enum flow_control    flow_mode;
         enum flow_control    flow_status;