From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- net/core/dst.c | 276 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 276 insertions(+) create mode 100644 net/core/dst.c (limited to 'net/core/dst.c') 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, + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +/* 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); -- cgit v1.2.3-59-g8ed1b