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Commit b891a902 authored by Catalin Marinas's avatar Catalin Marinas Committed by Jeff Garzik
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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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 319edafe

drivers/net/smc911x.c

+8 −17
Original line number Diff line number Diff line
@@ -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;

}