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smc911x: Make the driver safer on SMP
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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>
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Catalin Marinas authored and Jeff Garzik committed Oct 22, 2008
1 parent 319edaf commit b891a90
Showing 1 changed file with 8 additions and 17 deletions.
25 changes: 8 additions & 17 deletions drivers/net/smc911x.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)

/*
Expand Down Expand Up @@ -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 */
Expand All @@ -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_);
Expand All @@ -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);
Expand All @@ -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);
}

/*
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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_);
}

Expand All @@ -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_;
Expand All @@ -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
Expand All @@ -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;
}
Expand All @@ -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;
Expand All @@ -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;
}
Expand Down

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