1 files changed, 276 insertions, 0 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
new file mode 100644
index 000000000000..3bf6cc434814
--- /dev/null
+++ b/net/core/dst.c
@@ -0,0 +1,276 @@
+/*
+ * net/core/dst.c	Protocol independent destination cache.
+ *
+ * Authors:		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/sched.h>
+#include <linux/skbuff.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include <net/dst.h>
+
+/* Locking strategy:
+ * 1) Garbage collection state of dead destination cache
+ *    entries is protected by dst_lock.
+ * 2) GC is run only from BH context, and is the only remover
+ *    of entries.
+ * 3) Entries are added to the garbage list from both BH
+ *    and non-BH context, so local BH disabling is needed.
+ * 4) All operations modify state, so a spinlock is used.
+ */
+static struct dst_entry 	*dst_garbage_list;
+#if RT_CACHE_DEBUG >= 2 
+static atomic_t			 dst_total = ATOMIC_INIT(0);
+#endif
+static DEFINE_SPINLOCK(dst_lock);
+
+static unsigned long dst_gc_timer_expires;
+static unsigned long dst_gc_timer_inc = DST_GC_MAX;
+static void dst_run_gc(unsigned long);
+static void ___dst_free(struct dst_entry * dst);
+
+static struct timer_list dst_gc_timer =
+	TIMER_INITIALIZER(dst_run_gc, DST_GC_MIN, 0);
+
+static void dst_run_gc(unsigned long dummy)
+{
+	int    delayed = 0;
+	struct dst_entry * dst, **dstp;
+
+	if (!spin_trylock(&dst_lock)) {
+		mod_timer(&dst_gc_timer, jiffies + HZ/10);
+		return;
+	}
+
+
+	del_timer(&dst_gc_timer);
+	dstp = &dst_garbage_list;
+	while ((dst = *dstp) != NULL) {
+		if (atomic_read(&dst->__refcnt)) {
+			dstp = &dst->next;
+			delayed++;
+			continue;
+		}
+		*dstp = dst->next;
+
+		dst = dst_destroy(dst);
+		if (dst) {
+			/* NOHASH and still referenced. Unless it is already
+			 * on gc list, invalidate it and add to gc list.
+			 *
+			 * Note: this is temporary. Actually, NOHASH dst's
+			 * must be obsoleted when parent is obsoleted.
+			 * But we do not have state "obsoleted, but
+			 * referenced by parent", so it is right.
+			 */
+			if (dst->obsolete > 1)
+				continue;
+
+			___dst_free(dst);
+			dst->next = *dstp;
+			*dstp = dst;
+			dstp = &dst->next;
+		}
+	}
+	if (!dst_garbage_list) {
+		dst_gc_timer_inc = DST_GC_MAX;
+		goto out;
+	}
+	if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
+		dst_gc_timer_expires = DST_GC_MAX;
+	dst_gc_timer_inc += DST_GC_INC;
+	dst_gc_timer.expires = jiffies + dst_gc_timer_expires;
+#if RT_CACHE_DEBUG >= 2
+	printk("dst_total: %d/%d %ld\n",
+	       atomic_read(&dst_total), delayed,  dst_gc_timer_expires);
+#endif
+	add_timer(&dst_gc_timer);
+
+out:
+	spin_unlock(&dst_lock);
+}
+
+static int dst_discard_in(struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return 0;
+}
+
+static int dst_discard_out(struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return 0;
+}
+
+void * dst_alloc(struct dst_ops * ops)
+{
+	struct dst_entry * dst;
+
+	if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
+		if (ops->gc())
+			return NULL;
+	}
+	dst = kmem_cache_alloc(ops->kmem_cachep, SLAB_ATOMIC);
+	if (!dst)
+		return NULL;
+	memset(dst, 0, ops->entry_size);
+	atomic_set(&dst->__refcnt, 0);
+	dst->ops = ops;
+	dst->lastuse = jiffies;
+	dst->path = dst;
+	dst->input = dst_discard_in;
+	dst->output = dst_discard_out;
+#if RT_CACHE_DEBUG >= 2 
+	atomic_inc(&dst_total);
+#endif
+	atomic_inc(&ops->entries);
+	return dst;
+}
+
+static void ___dst_free(struct dst_entry * dst)
+{
+	/* The first case (dev==NULL) is required, when
+	   protocol module is unloaded.
+	 */
+	if (dst->dev == NULL || !(dst->dev->flags&IFF_UP)) {
+		dst->input = dst_discard_in;
+		dst->output = dst_discard_out;
+	}
+	dst->obsolete = 2;
+}
+
+void __dst_free(struct dst_entry * dst)
+{
+	spin_lock_bh(&dst_lock);
+	___dst_free(dst);
+	dst->next = dst_garbage_list;
+	dst_garbage_list = dst;
+	if (dst_gc_timer_inc > DST_GC_INC) {
+		dst_gc_timer_inc = DST_GC_INC;
+		dst_gc_timer_expires = DST_GC_MIN;
+		mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);
+	}
+	spin_unlock_bh(&dst_lock);
+}
+
+struct dst_entry *dst_destroy(struct dst_entry * dst)
+{
+	struct dst_entry *child;
+	struct neighbour *neigh;
+	struct hh_cache *hh;
+
+	smp_rmb();
+
+again:
+	neigh = dst->neighbour;
+	hh = dst->hh;
+	child = dst->child;
+
+	dst->hh = NULL;
+	if (hh && atomic_dec_and_test(&hh->hh_refcnt))
+		kfree(hh);
+
+	if (neigh) {
+		dst->neighbour = NULL;
+		neigh_release(neigh);
+	}
+
+	atomic_dec(&dst->ops->entries);
+
+	if (dst->ops->destroy)
+		dst->ops->destroy(dst);
+	if (dst->dev)
+		dev_put(dst->dev);
+#if RT_CACHE_DEBUG >= 2 
+	atomic_dec(&dst_total);
+#endif
+	kmem_cache_free(dst->ops->kmem_cachep, dst);
+
+	dst = child;
+	if (dst) {
+		if (atomic_dec_and_test(&dst->__refcnt)) {
+			/* We were real parent of this dst, so kill child. */
+			if (dst->flags&DST_NOHASH)
+				goto again;
+		} else {
+			/* Child is still referenced, return it for freeing. */
+			if (dst->flags&DST_NOHASH)
+				return dst;
+			/* Child is still in his hash table */
+		}
+	}
+	return NULL;
+}
+
+/* Dirty hack. We did it in 2.2 (in __dst_free),
+ * we have _very_ good reasons not to repeat
+ * this mistake in 2.3, but we have no choice
+ * now. _It_ _is_ _explicit_ _deliberate_
+ * _race_ _condition_.
+ *
+ * Commented and originally written by Alexey.
+ */
+static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
+			      int unregister)
+{
+	if (dst->ops->ifdown)
+		dst->ops->ifdown(dst, dev, unregister);
+
+	if (dev != dst->dev)
+		return;
+
+	if (!unregister) {
+		dst->input = dst_discard_in;
+		dst->output = dst_discard_out;
+	} else {
+		dst->dev = &loopback_dev;
+		dev_hold(&loopback_dev);
+		dev_put(dev);
+		if (dst->neighbour && dst->neighbour->dev == dev) {
+			dst->neighbour->dev = &loopback_dev;
+			dev_put(dev);
+			dev_hold(&loopback_dev);
+		}
+	}
+}
+
+static int dst_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *dev = ptr;
+	struct dst_entry *dst;
+
+	switch (event) {
+	case NETDEV_UNREGISTER:
+	case NETDEV_DOWN:
+		spin_lock_bh(&dst_lock);
+		for (dst = dst_garbage_list; dst; dst = dst->next) {
+			dst_ifdown(dst, dev, event != NETDEV_DOWN);
+		}
+		spin_unlock_bh(&dst_lock);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block dst_dev_notifier = {
+	.notifier_call	= dst_dev_event,
+};
+
+void __init dst_init(void)
+{
+	register_netdevice_notifier(&dst_dev_notifier);
+}
+
+EXPORT_SYMBOL(__dst_free);
+EXPORT_SYMBOL(dst_alloc);
+EXPORT_SYMBOL(dst_destroy);