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net/mpc5200: Fix locking on fec_mpc52xx driver 

Fix the locking scheme on the fec_mpc52xx driver.  This device can
receive IRQs from three sources; the FEC itself, the tx DMA, and the
rx DMA.  Mutual exclusion was handled by taking a spin_lock() in the
critical regions, but because the handlers are run with IRQs enabled,
spin_lock() is insufficient and the driver can end up interrupting
a critical region anyway from another IRQ.

Asier Llano discovered that this occurs when an error IRQ is raised
in the middle of handling rx irqs which resulted in an sk_buff memory
leak.

In addition, locking is spotty at best in the driver and inspection
revealed quite a few places with insufficient locking.

This patch is based on Asier's initial work, but reworks a number of
things so that locks are held for as short a time as possible, so
that spin_lock_irqsave() is used everywhere, and so the locks are
dropped when calling into the network stack (because the lock only
protects the hardware interface; not the network stack).

Boot tested on a lite5200 with an NFS root.  Has not been performance
tested.

Signed-off-by: Asier Llano <a.llano@ziv.es>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Asier Llano 2009-12-08 20:29:10 -08:00 committed by David S. Miller
parent 4b860abf63
commit 1e4e0767ec
1 changed files with 62 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

121
drivers/net/fec_mpc52xx.c
View File

@ -85,11 +85,15 @@ MODULE_PARM_DESC(debug, "debugging messages level");
static void mpc52xx_fec_tx_timeout(struct net_device *dev)
{
struct mpc52xx_fec_priv *priv = netdev_priv(dev);
unsigned long flags;
dev_warn(&dev->dev, "transmit timed out\n");
spin_lock_irqsave(&priv->lock, flags);
mpc52xx_fec_reset(dev);
dev->stats.tx_errors++;
spin_unlock_irqrestore(&priv->lock, flags);
netif_wake_queue(dev);
}
@ -135,28 +139,32 @@ static void mpc52xx_fec_free_rx_buffers(struct net_device *dev, struct bcom_task
}
}
static void
mpc52xx_fec_rx_submit(struct net_device *dev, struct sk_buff *rskb)
{
struct mpc52xx_fec_priv *priv = netdev_priv(dev);
struct bcom_fec_bd *bd;
bd = (struct bcom_fec_bd *) bcom_prepare_next_buffer(priv->rx_dmatsk);
bd->status = FEC_RX_BUFFER_SIZE;
bd->skb_pa = dma_map_single(dev->dev.parent, rskb->data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
bcom_submit_next_buffer(priv->rx_dmatsk, rskb);
}
static int mpc52xx_fec_alloc_rx_buffers(struct net_device *dev, struct bcom_task *rxtsk)
{
while (!bcom_queue_full(rxtsk)) {
struct sk_buff *skb;
struct bcom_fec_bd *bd;
struct sk_buff *skb;
while (!bcom_queue_full(rxtsk)) {
skb = dev_alloc_skb(FEC_RX_BUFFER_SIZE);
if (skb == NULL)
if (!skb)
return -EAGAIN;
/* zero out the initial receive buffers to aid debugging */
memset(skb->data, 0, FEC_RX_BUFFER_SIZE);
bd = (struct bcom_fec_bd *)bcom_prepare_next_buffer(rxtsk);
bd->status = FEC_RX_BUFFER_SIZE;
bd->skb_pa = dma_map_single(dev->dev.parent, skb->data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
bcom_submit_next_buffer(rxtsk, skb);
mpc52xx_fec_rx_submit(dev, skb);
}
return 0;
}
@ -328,13 +336,12 @@ static int mpc52xx_fec_start_xmit(struct sk_buff *skb, struct net_device *dev)
DMA_TO_DEVICE);
bcom_submit_next_buffer(priv->tx_dmatsk, skb);
spin_unlock_irqrestore(&priv->lock, flags);
if (bcom_queue_full(priv->tx_dmatsk)) {
netif_stop_queue(dev);
}
spin_unlock_irqrestore(&priv->lock, flags);
return NETDEV_TX_OK;
}
@ -359,9 +366,9 @@ static irqreturn_t mpc52xx_fec_tx_interrupt(int irq, void *dev_id)
{
struct net_device *dev = dev_id;
struct mpc52xx_fec_priv *priv = netdev_priv(dev);
unsigned long flags;
spin_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, flags);
while (bcom_buffer_done(priv->tx_dmatsk)) {
struct sk_buff *skb;
struct bcom_fec_bd *bd;
@ -372,11 +379,10 @@ static irqreturn_t mpc52xx_fec_tx_interrupt(int irq, void *dev_id)
dev_kfree_skb_irq(skb);
}
spin_unlock_irqrestore(&priv->lock, flags);
netif_wake_queue(dev);
spin_unlock(&priv->lock);
return IRQ_HANDLED;
}
@ -384,67 +390,60 @@ static irqreturn_t mpc52xx_fec_rx_interrupt(int irq, void *dev_id)
{
struct net_device *dev = dev_id;
struct mpc52xx_fec_priv *priv = netdev_priv(dev);
struct sk_buff *rskb; /* received sk_buff */
struct sk_buff *skb; /* new sk_buff to enqueue in its place */
struct bcom_fec_bd *bd;
u32 status, physaddr;
int length;
unsigned long flags;
spin_lock_irqsave(&priv->lock, flags);
while (bcom_buffer_done(priv->rx_dmatsk)) {
struct sk_buff *skb;
struct sk_buff *rskb;
struct bcom_fec_bd *bd;
u32 status;
rskb = bcom_retrieve_buffer(priv->rx_dmatsk, &status,
(struct bcom_bd **)&bd);
dma_unmap_single(dev->dev.parent, bd->skb_pa, rskb->len,
DMA_FROM_DEVICE);
(struct bcom_bd **)&bd);
physaddr = bd->skb_pa;
/* Test for errors in received frame */
if (status & BCOM_FEC_RX_BD_ERRORS) {
/* Drop packet and reuse the buffer */
bd = (struct bcom_fec_bd *)
bcom_prepare_next_buffer(priv->rx_dmatsk);
bd->status = FEC_RX_BUFFER_SIZE;
bd->skb_pa = dma_map_single(dev->dev.parent,
rskb->data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
bcom_submit_next_buffer(priv->rx_dmatsk, rskb);
mpc52xx_fec_rx_submit(dev, rskb);
dev->stats.rx_dropped++;
continue;
}
/* skbs are allocated on open, so now we allocate a new one,
* and remove the old (with the packet) */
skb = dev_alloc_skb(FEC_RX_BUFFER_SIZE);
if (skb) {
/* Process the received skb */
int length = status & BCOM_FEC_RX_BD_LEN_MASK;
skb_put(rskb, length - 4); /* length without CRC32 */
rskb->dev = dev;
rskb->protocol = eth_type_trans(rskb, dev);
netif_rx(rskb);
} else {
if (!skb) {
/* Can't get a new one : reuse the same & drop pkt */
dev_notice(&dev->dev, "Memory squeeze, dropping packet.\n");
dev_notice(&dev->dev, "Low memory - dropped packet.\n");
mpc52xx_fec_rx_submit(dev, rskb);
dev->stats.rx_dropped++;
skb = rskb;
continue;
}
bd = (struct bcom_fec_bd *)
bcom_prepare_next_buffer(priv->rx_dmatsk);
/* Enqueue the new sk_buff back on the hardware */
mpc52xx_fec_rx_submit(dev, skb);
bd->status = FEC_RX_BUFFER_SIZE;
bd->skb_pa = dma_map_single(dev->dev.parent, skb->data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
/* Process the received skb - Drop the spin lock while
* calling into the network stack */
spin_unlock_irqrestore(&priv->lock, flags);
bcom_submit_next_buffer(priv->rx_dmatsk, skb);
dma_unmap_single(dev->dev.parent, physaddr, rskb->len,
DMA_FROM_DEVICE);
length = status & BCOM_FEC_RX_BD_LEN_MASK;
skb_put(rskb, length - 4); /* length without CRC32 */
rskb->dev = dev;
rskb->protocol = eth_type_trans(rskb, dev);
netif_rx(rskb);
spin_lock_irqsave(&priv->lock, flags);
}
spin_unlock_irqrestore(&priv->lock, flags);
return IRQ_HANDLED;
}
@ -454,6 +453,7 @@ static irqreturn_t mpc52xx_fec_interrupt(int irq, void *dev_id)
struct mpc52xx_fec_priv *priv = netdev_priv(dev);
struct mpc52xx_fec __iomem *fec = priv->fec;
u32 ievent;
unsigned long flags;
ievent = in_be32(&fec->ievent);
@ -471,9 +471,10 @@ static irqreturn_t mpc52xx_fec_interrupt(int irq, void *dev_id)
if (net_ratelimit() && (ievent & FEC_IEVENT_XFIFO_ERROR))
dev_warn(&dev->dev, "FEC_IEVENT_XFIFO_ERROR\n");
spin_lock_irqsave(&priv->lock, flags);
mpc52xx_fec_reset(dev);
spin_unlock_irqrestore(&priv->lock, flags);
netif_wake_queue(dev);
return IRQ_HANDLED;
}
@ -768,6 +769,8 @@ static void mpc52xx_fec_reset(struct net_device *dev)
bcom_enable(priv->tx_dmatsk);
mpc52xx_fec_start(dev);
netif_wake_queue(dev);
}