[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>

1 files changed, 28 insertions, 28 deletions

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 771e25d8c417..218d31764c52 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