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-rw-r--r--net/core/dst.c276
1 files changed, 276 insertions, 0 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
new file mode 100644
index 00000000000..3bf6cc43481
--- /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);