smc911x: Make the driver safer on SMP

This patch extends the critical regions covered by lp->lock to make it
safer on SMP. The main failure point was the smc911x_hard_start_xmit
function being called from different CPUs. It was tested on the ARM SMP
platforms.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/net/smc911x.c b/drivers/net/smc911x.c
index 2c78229..f59c777 100644 (file)
--- a/drivers/net/smc911x.c
+++ b/drivers/net/smc911x.c
@@ -155,23 +155,17 @@ static void PRINT_PKT(u_char *buf, int length)
 /* this enables an interrupt in the interrupt mask register */
 #define SMC_ENABLE_INT(lp, x) do {                     \
        unsigned int  __mask;                           \
-       unsigned long __flags;                          \
-       spin_lock_irqsave(&lp->lock, __flags);          \
        __mask = SMC_GET_INT_EN((lp));                  \
        __mask |= (x);                                  \
        SMC_SET_INT_EN((lp), __mask);                   \
-       spin_unlock_irqrestore(&lp->lock, __flags);     \
 } while (0)
 
 /* this disables an interrupt from the interrupt mask register */
 #define SMC_DISABLE_INT(lp, x) do {                    \
        unsigned int  __mask;                           \
-       unsigned long __flags;                          \
-       spin_lock_irqsave(&lp->lock, __flags);          \
        __mask = SMC_GET_INT_EN((lp));                  \
        __mask &= ~(x);                                 \
        SMC_SET_INT_EN((lp), __mask);                   \
-       spin_unlock_irqrestore(&lp->lock, __flags);     \
 } while (0)
 
 /*
@@ -279,6 +273,8 @@ static void smc911x_enable(struct net_device *dev)
 
        DBG(SMC_DEBUG_FUNC, "%s: --> %s\n", dev->name, __func__);
 
+       spin_lock_irqsave(&lp->lock, flags);
+
        SMC_SET_MAC_ADDR(lp, dev->dev_addr);
 
        /* Enable TX */
@@ -291,12 +287,10 @@ static void smc911x_enable(struct net_device *dev)
        SMC_SET_FIFO_TSL(lp, 64);
        SMC_SET_GPT_CFG(lp, GPT_CFG_TIMER_EN_ | 10000);
 
-       spin_lock_irqsave(&lp->lock, flags);
        SMC_GET_MAC_CR(lp, cr);
        cr |= MAC_CR_TXEN_ | MAC_CR_HBDIS_;
        SMC_SET_MAC_CR(lp, cr);
        SMC_SET_TX_CFG(lp, TX_CFG_TX_ON_);
-       spin_unlock_irqrestore(&lp->lock, flags);
 
        /* Add 2 byte padding to start of packets */
        SMC_SET_RX_CFG(lp, (2<<8) & RX_CFG_RXDOFF_);
@@ -305,9 +299,7 @@ static void smc911x_enable(struct net_device *dev)
        if (cr & MAC_CR_RXEN_)
                DBG(SMC_DEBUG_RX, "%s: Receiver already enabled\n", dev->name);
 
-       spin_lock_irqsave(&lp->lock, flags);
        SMC_SET_MAC_CR(lp, cr | MAC_CR_RXEN_);
-       spin_unlock_irqrestore(&lp->lock, flags);
 
        /* Interrupt on every received packet */
        SMC_SET_FIFO_RSA(lp, 0x01);
@@ -323,6 +315,8 @@ static void smc911x_enable(struct net_device *dev)
                mask|=INT_EN_RDFO_EN_;
        }
        SMC_ENABLE_INT(lp, mask);
+
+       spin_unlock_irqrestore(&lp->lock, flags);
 }
 
 /*
@@ -463,7 +457,6 @@ static void smc911x_hardware_send_pkt(struct net_device *dev)
        struct sk_buff *skb;
        unsigned int cmdA, cmdB, len;
        unsigned char *buf;
-       unsigned long flags;
 
        DBG(SMC_DEBUG_FUNC | SMC_DEBUG_TX, "%s: --> %s\n", dev->name, __func__);
        BUG_ON(lp->pending_tx_skb == NULL);
@@ -508,11 +501,9 @@ static void smc911x_hardware_send_pkt(struct net_device *dev)
        dev->trans_start = jiffies;
        dev_kfree_skb(skb);
 #endif
-       spin_lock_irqsave(&lp->lock, flags);
        if (!lp->tx_throttle) {
                netif_wake_queue(dev);
        }
-       spin_unlock_irqrestore(&lp->lock, flags);
        SMC_ENABLE_INT(lp, INT_EN_TDFA_EN_ | INT_EN_TSFL_EN_);
 }
 
@@ -531,6 +522,8 @@ static int smc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
        DBG(SMC_DEBUG_FUNC | SMC_DEBUG_TX, "%s: --> %s\n",
                dev->name, __func__);
 
+       spin_lock_irqsave(&lp->lock, flags);
+
        BUG_ON(lp->pending_tx_skb != NULL);
 
        free = SMC_GET_TX_FIFO_INF(lp) & TX_FIFO_INF_TDFREE_;
@@ -540,12 +533,10 @@ static int smc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
        if (free <= SMC911X_TX_FIFO_LOW_THRESHOLD) {
                DBG(SMC_DEBUG_TX, "%s: Disabling data flow due to low FIFO space (%d)\n",
                        dev->name, free);
-               spin_lock_irqsave(&lp->lock, flags);
                /* Reenable when at least 1 packet of size MTU present */
                SMC_SET_FIFO_TDA(lp, (SMC911X_TX_FIFO_LOW_THRESHOLD)/64);
                lp->tx_throttle = 1;
                netif_stop_queue(dev);
-               spin_unlock_irqrestore(&lp->lock, flags);
        }
 
        /* Drop packets when we run out of space in TX FIFO
@@ -561,6 +552,7 @@ static int smc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
                lp->pending_tx_skb = NULL;
                dev->stats.tx_errors++;
                dev->stats.tx_dropped++;
+               spin_unlock_irqrestore(&lp->lock, flags);
                dev_kfree_skb(skb);
                return 0;
        }
@@ -570,7 +562,6 @@ static int smc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
                /* If the DMA is already running then defer this packet Tx until
                 * the DMA IRQ starts it
                 */
-               spin_lock_irqsave(&lp->lock, flags);
                if (lp->txdma_active) {
                        DBG(SMC_DEBUG_TX | SMC_DEBUG_DMA, "%s: Tx DMA running, deferring packet\n", dev->name);
                        lp->pending_tx_skb = skb;
@@ -581,11 +572,11 @@ static int smc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
                        DBG(SMC_DEBUG_TX | SMC_DEBUG_DMA, "%s: Activating Tx DMA\n", dev->name);
                        lp->txdma_active = 1;
                }
-               spin_unlock_irqrestore(&lp->lock, flags);
        }
 #endif
        lp->pending_tx_skb = skb;
        smc911x_hardware_send_pkt(dev);
+       spin_unlock_irqrestore(&lp->lock, flags);
 
        return 0;
 }