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-rw-r--r--arch/um/drivers/net_kern.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index 59811cc880e0..8c01fa81a1ae 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -34,6 +34,46 @@ static inline void set_ether_mac(struct net_device *dev, unsigned char *addr)
static DEFINE_SPINLOCK(opened_lock);
static LIST_HEAD(opened);
+/*
+ * The drop_skb is used when we can't allocate an skb. The
+ * packet is read into drop_skb in order to get the data off the
+ * connection to the host.
+ * It is reallocated whenever a maximum packet size is seen which is
+ * larger than any seen before. update_drop_skb is called from
+ * eth_configure when a new interface is added.
+ */
+static DEFINE_SPINLOCK(drop_lock);
+static struct sk_buff *drop_skb;
+static int drop_max;
+
+static int update_drop_skb(int max)
+{
+ struct sk_buff *new;
+ unsigned long flags;
+ int err = 0;
+
+ spin_lock_irqsave(&drop_lock, flags);
+
+ if (max <= drop_max)
+ goto out;
+
+ err = -ENOMEM;
+ new = dev_alloc_skb(max);
+ if (new == NULL)
+ goto out;
+
+ skb_put(new, max);
+
+ kfree_skb(drop_skb);
+ drop_skb = new;
+ drop_max = max;
+ err = 0;
+out:
+ spin_unlock_irqrestore(&drop_lock, flags);
+
+ return err;
+}
+
static int uml_net_rx(struct net_device *dev)
{
struct uml_net_private *lp = dev->priv;
@@ -43,6 +83,9 @@ static int uml_net_rx(struct net_device *dev)
/* If we can't allocate memory, try again next round. */
skb = dev_alloc_skb(lp->max_packet);
if (skb == NULL) {
+ drop_skb->dev = dev;
+ /* Read a packet into drop_skb and don't do anything with it. */
+ (*lp->read)(lp->fd, drop_skb, lp);
lp->stats.rx_dropped++;
return 0;
}
@@ -447,6 +490,10 @@ static void eth_configure(int n, void *init, char *mac,
dev->watchdog_timeo = (HZ >> 1);
dev->irq = UM_ETH_IRQ;
+ err = update_drop_skb(lp->max_packet);
+ if (err)
+ goto out_undo_user_init;
+
rtnl_lock();
err = register_netdevice(dev);
rtnl_unlock();