[PATCH] Fix locking in gianfar

This patch fixes several bugs in the gianfar driver, including a major one
where spinlocks were horribly broken:

* Split gianfar locks into two types: TX and RX
* Made it so gfar_start() now clears RHALT
* Fixed a bug where calling gfar_start_xmit() with interrupts off would
corrupt the interrupt state
* Fixed a bug where a frame could potentially arrive, and never be handled
(if no more frames arrived
* Fixed a bug where the rx_work_limit would never be observed by the rx
completion code
* Fixed a bug where the interrupt handlers were not actually protected by
their spinlocks

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

4 files changed, 100 insertions, 67 deletions

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 771e25d..218d317 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -210,7 +210,8 @@ static int gfar_probe(struct platform_device *pdev)
 		goto regs_fail;
 	}
 
-	spin_lock_init(&priv->lock);
+	spin_lock_init(&priv->txlock);
+	spin_lock_init(&priv->rxlock);
 
 	platform_set_drvdata(pdev, dev);
 
@@ -515,11 +516,13 @@ void stop_gfar(struct net_device *dev)
 	phy_stop(priv->phydev);
 
 	/* Lock it down */
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
+	spin_lock(&priv->rxlock);
 
 	gfar_halt(dev);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock(&priv->rxlock);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	/* Free the IRQs */
 	if (priv->einfo->device_flags & FSL_GIANFAR_DEV_HAS_MULTI_INTR) {
@@ -605,14 +608,15 @@ void gfar_start(struct net_device *dev)
 	tempval |= DMACTRL_INIT_SETTINGS;
 	gfar_write(&priv->regs->dmactrl, tempval);
 
-	/* Clear THLT, so that the DMA starts polling now */
-	gfar_write(&regs->tstat, TSTAT_CLEAR_THALT);
-
 	/* Make sure we aren't stopped */
 	tempval = gfar_read(&priv->regs->dmactrl);
 	tempval &= ~(DMACTRL_GRS | DMACTRL_GTS);
 	gfar_write(&priv->regs->dmactrl, tempval);
 
+	/* Clear THLT/RHLT, so that the DMA starts polling now */
+	gfar_write(&regs->tstat, TSTAT_CLEAR_THALT);
+	gfar_write(&regs->rstat, RSTAT_CLEAR_RHALT);
+
 	/* Unmask the interrupts we look for */
 	gfar_write(&regs->imask, IMASK_DEFAULT);
 }
@@ -928,12 +932,13 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct txfcb *fcb = NULL;
 	struct txbd8 *txbdp;
 	u16 status;
+	unsigned long flags;
 
 	/* Update transmit stats */
 	priv->stats.tx_bytes += skb->len;
 
 	/* Lock priv now */
-	spin_lock_irq(&priv->lock);
+	spin_lock_irqsave(&priv->txlock, flags);
 
 	/* Point at the first free tx descriptor */
 	txbdp = priv->cur_tx;
@@ -1004,7 +1009,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	gfar_write(&priv->regs->tstat, TSTAT_CLEAR_THALT);
 
 	/* Unlock priv */
-	spin_unlock_irq(&priv->lock);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	return 0;
 }
@@ -1049,7 +1054,7 @@ static void gfar_vlan_rx_register(struct net_device *dev,
 	unsigned long flags;
 	u32 tempval;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->rxlock, flags);
 
 	priv->vlgrp = grp;
 
@@ -1076,7 +1081,7 @@ static void gfar_vlan_rx_register(struct net_device *dev,
 		gfar_write(&priv->regs->rctrl, tempval);
 	}
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 }
 
 
@@ -1085,12 +1090,12 @@ static void gfar_vlan_rx_kill_vid(struct net_device *dev, uint16_t vid)
 	struct gfar_private *priv = netdev_priv(dev);
 	unsigned long flags;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->rxlock, flags);
 
 	if (priv->vlgrp)
 		priv->vlgrp->vlan_devices[vid] = NULL;
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 }
 
 
@@ -1179,7 +1184,7 @@ static irqreturn_t gfar_transmit(int irq, void *dev_id, struct pt_regs *regs)
 	gfar_write(&priv->regs->ievent, IEVENT_TX_MASK);
 
 	/* Lock priv */
-	spin_lock(&priv->lock);
+	spin_lock(&priv->txlock);
 	bdp = priv->dirty_tx;
 	while ((bdp->status & TXBD_READY) == 0) {
 		/* If dirty_tx and cur_tx are the same, then either the */
@@ -1224,7 +1229,7 @@ static irqreturn_t gfar_transmit(int irq, void *dev_id, struct pt_regs *regs)
 	else
 		gfar_write(&priv->regs->txic, 0);
 
-	spin_unlock(&priv->lock);
+	spin_unlock(&priv->txlock);
 
 	return IRQ_HANDLED;
 }
@@ -1305,9 +1310,10 @@ irqreturn_t gfar_receive(int irq, void *dev_id, struct pt_regs *regs)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct gfar_private *priv = netdev_priv(dev);
-
 #ifdef CONFIG_GFAR_NAPI
 	u32 tempval;
+#else
+	unsigned long flags;
 #endif
 
 	/* Clear IEVENT, so rx interrupt isn't called again
@@ -1330,7 +1336,7 @@ irqreturn_t gfar_receive(int irq, void *dev_id, struct pt_regs *regs)
 	}
 #else
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->rxlock, flags);
 	gfar_clean_rx_ring(dev, priv->rx_ring_size);
 
 	/* If we are coalescing interrupts, update the timer */
@@ -1341,7 +1347,7 @@ irqreturn_t gfar_receive(int irq, void *dev_id, struct pt_regs *regs)
 	else
 		gfar_write(&priv->regs->rxic, 0);
 
-	spin_unlock(&priv->lock);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 #endif
 
 	return IRQ_HANDLED;
@@ -1490,13 +1496,6 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit)
 	/* Update the current rxbd pointer to be the next one */
 	priv->cur_rx = bdp;
 
-	/* If no packets have arrived since the
-	 * last one we processed, clear the IEVENT RX and
-	 * BSY bits so that another interrupt won't be
-	 * generated when we set IMASK */
-	if (bdp->status & RXBD_EMPTY)
-		gfar_write(&priv->regs->ievent, IEVENT_RX_MASK);
-
 	return howmany;
 }
 
@@ -1516,7 +1515,7 @@ static int gfar_poll(struct net_device *dev, int *budget)
 	rx_work_limit -= howmany;
 	*budget -= howmany;
 
-	if (rx_work_limit >= 0) {
+	if (rx_work_limit > 0) {
 		netif_rx_complete(dev);
 
 		/* Clear the halt bit in RSTAT */
@@ -1533,7 +1532,8 @@ static int gfar_poll(struct net_device *dev, int *budget)
 			gfar_write(&priv->regs->rxic, 0);
 	}
 
-	return (rx_work_limit < 0) ? 1 : 0;
+	/* Return 1 if there's more work to do */
+	return (rx_work_limit > 0) ? 0 : 1;
 }
 #endif
 
@@ -1629,7 +1629,7 @@ static void adjust_link(struct net_device *dev)
 	struct phy_device *phydev = priv->phydev;
 	int new_state = 0;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
 	if (phydev->link) {
 		u32 tempval = gfar_read(&regs->maccfg2);
 		u32 ecntrl = gfar_read(&regs->ecntrl);
@@ -1694,7 +1694,7 @@ static void adjust_link(struct net_device *dev)
 	if (new_state && netif_msg_link(priv))
 		phy_print_status(phydev);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 }
 
 /* Update the hash table based on the current list of multicast
diff --git a/drivers/net/gianfar.h b/drivers/net/gianfar.h
index d37d540..127c98c 100644
--- a/drivers/net/gianfar.h
+++ b/drivers/net/gianfar.h
@@ -656,43 +656,62 @@ struct gfar {
  * the buffer descriptor determines the actual condition.
  */
 struct gfar_private {
-	/* pointers to arrays of skbuffs for tx and rx */
+	/* Fields controlled by TX lock */
+	spinlock_t txlock;
+
+	/* Pointer to the array of skbuffs */
 	struct sk_buff ** tx_skbuff;
-	struct sk_buff ** rx_skbuff;
 
-	/* indices pointing to the next free sbk in skb arrays */
+	/* next free skb in the array */
 	u16 skb_curtx;
-	u16 skb_currx;
 
-	/* index of the first skb which hasn't been transmitted
-	 * yet. */
+	/* First skb in line to be transmitted */
 	u16 skb_dirtytx;
 
 	/* Configuration info for the coalescing features */
 	unsigned char txcoalescing;
 	unsigned short txcount;
 	unsigned short txtime;
+
+	/* Buffer descriptor pointers */
+	struct txbd8 *tx_bd_base;	/* First tx buffer descriptor */
+	struct txbd8 *cur_tx;	        /* Next free ring entry */
+	struct txbd8 *dirty_tx;		/* First buffer in line
+					   to be transmitted */
+	unsigned int tx_ring_size;
+
+	/* RX Locked fields */
+	spinlock_t rxlock;
+
+	/* skb array and index */
+	struct sk_buff ** rx_skbuff;
+	u16 skb_currx;
+
+	/* RX Coalescing values */
 	unsigned char rxcoalescing;
 	unsigned short rxcount;
 	unsigned short rxtime;
 
-	/* GFAR addresses */
-	struct rxbd8 *rx_bd_base;	/* Base addresses of Rx and Tx Buffers */
-	struct txbd8 *tx_bd_base;
+	struct rxbd8 *rx_bd_base;	/* First Rx buffers */
 	struct rxbd8 *cur_rx;           /* Next free rx ring entry */
-	struct txbd8 *cur_tx;	        /* Next free ring entry */
-	struct txbd8 *dirty_tx;		/* The Ring entry to be freed. */
-	struct gfar __iomem *regs;	/* Pointer to the GFAR memory mapped Registers */
-	u32 __iomem *hash_regs[16];
-	int hash_width;
-	struct net_device_stats stats; /* linux network statistics */
-	struct gfar_extra_stats extra_stats;
-	spinlock_t lock;
+
+	/* RX parameters */
+	unsigned int rx_ring_size;
 	unsigned int rx_buffer_size;
 	unsigned int rx_stash_size;
 	unsigned int rx_stash_index;
-	unsigned int tx_ring_size;
-	unsigned int rx_ring_size;
+
+	struct vlan_group *vlgrp;
+
+	/* Unprotected fields */
+	/* Pointer to the GFAR memory mapped Registers */
+	struct gfar __iomem *regs;
+
+	/* Hash registers and their width */
+	u32 __iomem *hash_regs[16];
+	int hash_width;
+
+	/* global parameters */
 	unsigned int fifo_threshold;
 	unsigned int fifo_starve;
 	unsigned int fifo_starve_off;
@@ -702,13 +721,15 @@ struct gfar_private {
 		extended_hash:1,
 		bd_stash_en:1;
 	unsigned short padding;
-	struct vlan_group *vlgrp;
-	/* Info structure initialized by board setup code */
+
 	unsigned int interruptTransmit;
 	unsigned int interruptReceive;
 	unsigned int interruptError;
+
+	/* info structure initialized by platform code */
 	struct gianfar_platform_data *einfo;
 
+	/* PHY stuff */
 	struct phy_device *phydev;
 	struct mii_bus *mii_bus;
 	int oldspeed;
@@ -716,6 +737,10 @@ struct gfar_private {
 	int oldlink;
 
 	uint32_t msg_enable;
+
+	/* Network Statistics */
+	struct net_device_stats stats;
+	struct gfar_extra_stats extra_stats;
 };
 
 static inline u32 gfar_read(volatile unsigned __iomem *addr)
diff --git a/drivers/net/gianfar_ethtool.c b/drivers/net/gianfar_ethtool.c
index 5de7b2e..d69698c 100644
--- a/drivers/net/gianfar_ethtool.c
+++ b/drivers/net/gianfar_ethtool.c
@@ -455,10 +455,14 @@ static int gfar_sringparam(struct net_device *dev, struct ethtool_ringparam *rva
 
 		/* Halt TX and RX, and process the frames which
 		 * have already been received */
-		spin_lock_irqsave(&priv->lock, flags);
+		spin_lock_irqsave(&priv->txlock, flags);
+		spin_lock(&priv->rxlock);
+
 		gfar_halt(dev);
 		gfar_clean_rx_ring(dev, priv->rx_ring_size);
-		spin_unlock_irqrestore(&priv->lock, flags);
+
+		spin_unlock(&priv->rxlock);
+		spin_unlock_irqrestore(&priv->txlock, flags);
 
 		/* Now we take down the rings to rebuild them */
 		stop_gfar(dev);
@@ -488,10 +492,14 @@ static int gfar_set_rx_csum(struct net_device *dev, uint32_t data)
 
 		/* Halt TX and RX, and process the frames which
 		 * have already been received */
-		spin_lock_irqsave(&priv->lock, flags);
+		spin_lock_irqsave(&priv->txlock, flags);
+		spin_lock(&priv->rxlock);
+
 		gfar_halt(dev);
 		gfar_clean_rx_ring(dev, priv->rx_ring_size);
-		spin_unlock_irqrestore(&priv->lock, flags);
+
+		spin_unlock(&priv->rxlock);
+		spin_unlock_irqrestore(&priv->txlock, flags);
 
 		/* Now we take down the rings to rebuild them */
 		stop_gfar(dev);
@@ -523,7 +531,7 @@ static int gfar_set_tx_csum(struct net_device *dev, uint32_t data)
 	if (!(priv->einfo->device_flags & FSL_GIANFAR_DEV_HAS_CSUM))
 		return -EOPNOTSUPP;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
 	gfar_halt(dev);
 
 	if (data)
@@ -532,7 +540,7 @@ static int gfar_set_tx_csum(struct net_device *dev, uint32_t data)
 		dev->features &= ~NETIF_F_IP_CSUM;
 
 	gfar_start(dev);
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	return 0;
 }
diff --git a/drivers/net/gianfar_sysfs.c b/drivers/net/gianfar_sysfs.c
index 51ef181..a6d5c43 100644
--- a/drivers/net/gianfar_sysfs.c
+++ b/drivers/net/gianfar_sysfs.c
@@ -82,7 +82,7 @@ static ssize_t gfar_set_bd_stash(struct class_device *cdev,
 	else
 		return count;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->rxlock, flags);
 
 	/* Set the new stashing value */
 	priv->bd_stash_en = new_setting;
@@ -96,7 +96,7 @@ static ssize_t gfar_set_bd_stash(struct class_device *cdev,
 
 	gfar_write(&priv->regs->attr, temp);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 
 	return count;
 }
@@ -118,7 +118,7 @@ static ssize_t gfar_set_rx_stash_size(struct class_device *cdev,
 	u32 temp;
 	unsigned long flags;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->rxlock, flags);
 	if (length > priv->rx_buffer_size)
 		return count;
 
@@ -142,7 +142,7 @@ static ssize_t gfar_set_rx_stash_size(struct class_device *cdev,
 
 	gfar_write(&priv->regs->attr, temp);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 
 	return count;
 }
@@ -166,7 +166,7 @@ static ssize_t gfar_set_rx_stash_index(struct class_device *cdev,
 	u32 temp;
 	unsigned long flags;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->rxlock, flags);
 	if (index > priv->rx_stash_size)
 		return count;
 
@@ -180,7 +180,7 @@ static ssize_t gfar_set_rx_stash_index(struct class_device *cdev,
 	temp |= ATTRELI_EI(index);
 	gfar_write(&priv->regs->attreli, flags);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->rxlock, flags);
 
 	return count;
 }
@@ -205,7 +205,7 @@ static ssize_t gfar_set_fifo_threshold(struct class_device *cdev,
 	if (length > GFAR_MAX_FIFO_THRESHOLD)
 		return count;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
 
 	priv->fifo_threshold = length;
 
@@ -214,7 +214,7 @@ static ssize_t gfar_set_fifo_threshold(struct class_device *cdev,
 	temp |= length;
 	gfar_write(&priv->regs->fifo_tx_thr, temp);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	return count;
 }
@@ -240,7 +240,7 @@ static ssize_t gfar_set_fifo_starve(struct class_device *cdev,
 	if (num > GFAR_MAX_FIFO_STARVE)
 		return count;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
 
 	priv->fifo_starve = num;
 
@@ -249,7 +249,7 @@ static ssize_t gfar_set_fifo_starve(struct class_device *cdev,
 	temp |= num;
 	gfar_write(&priv->regs->fifo_tx_starve, temp);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	return count;
 }
@@ -274,7 +274,7 @@ static ssize_t gfar_set_fifo_starve_off(struct class_device *cdev,
 	if (num > GFAR_MAX_FIFO_STARVE_OFF)
 		return count;
 
-	spin_lock_irqsave(&priv->lock, flags);
+	spin_lock_irqsave(&priv->txlock, flags);
 
 	priv->fifo_starve_off = num;
 
@@ -283,7 +283,7 @@ static ssize_t gfar_set_fifo_starve_off(struct class_device *cdev,
 	temp |= num;
 	gfar_write(&priv->regs->fifo_tx_starve_shutoff, temp);
 
-	spin_unlock_irqrestore(&priv->lock, flags);
+	spin_unlock_irqrestore(&priv->txlock, flags);
 
 	return count;
 }