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![Denis V. Lunev](/assets/img/avatar_default.png)
Device inside the namespace can be started and downed. So, active routing cache should be cleaned up on device stop. Signed-off-by: Denis V. Lunev <den@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
336 lines
7.8 KiB
C
336 lines
7.8 KiB
C
/*
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* net/core/dst.c Protocol independent destination cache.
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*
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* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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*
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*/
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#include <linux/bitops.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/workqueue.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <net/net_namespace.h>
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#include <net/dst.h>
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/*
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* Theory of operations:
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* 1) We use a list, protected by a spinlock, to add
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* new entries from both BH and non-BH context.
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* 2) In order to keep spinlock held for a small delay,
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* we use a second list where are stored long lived
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* entries, that are handled by the garbage collect thread
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* fired by a workqueue.
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* 3) This list is guarded by a mutex,
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* so that the gc_task and dst_dev_event() can be synchronized.
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*/
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#if RT_CACHE_DEBUG >= 2
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static atomic_t dst_total = ATOMIC_INIT(0);
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#endif
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/*
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* We want to keep lock & list close together
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* to dirty as few cache lines as possible in __dst_free().
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* As this is not a very strong hint, we dont force an alignment on SMP.
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*/
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static struct {
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spinlock_t lock;
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struct dst_entry *list;
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unsigned long timer_inc;
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unsigned long timer_expires;
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} dst_garbage = {
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.lock = __SPIN_LOCK_UNLOCKED(dst_garbage.lock),
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.timer_inc = DST_GC_MAX,
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};
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static void dst_gc_task(struct work_struct *work);
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static void ___dst_free(struct dst_entry * dst);
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static DECLARE_DELAYED_WORK(dst_gc_work, dst_gc_task);
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static DEFINE_MUTEX(dst_gc_mutex);
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/*
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* long lived entries are maintained in this list, guarded by dst_gc_mutex
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*/
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static struct dst_entry *dst_busy_list;
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static void dst_gc_task(struct work_struct *work)
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{
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int delayed = 0;
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int work_performed = 0;
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unsigned long expires = ~0L;
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struct dst_entry *dst, *next, head;
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struct dst_entry *last = &head;
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#if RT_CACHE_DEBUG >= 2
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ktime_t time_start = ktime_get();
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struct timespec elapsed;
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#endif
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mutex_lock(&dst_gc_mutex);
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next = dst_busy_list;
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loop:
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while ((dst = next) != NULL) {
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next = dst->next;
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prefetch(&next->next);
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if (likely(atomic_read(&dst->__refcnt))) {
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last->next = dst;
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last = dst;
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delayed++;
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continue;
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}
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work_performed++;
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dst = dst_destroy(dst);
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if (dst) {
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/* NOHASH and still referenced. Unless it is already
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* on gc list, invalidate it and add to gc list.
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*
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* Note: this is temporary. Actually, NOHASH dst's
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* must be obsoleted when parent is obsoleted.
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* But we do not have state "obsoleted, but
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* referenced by parent", so it is right.
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*/
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if (dst->obsolete > 1)
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continue;
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___dst_free(dst);
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dst->next = next;
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next = dst;
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}
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}
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spin_lock_bh(&dst_garbage.lock);
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next = dst_garbage.list;
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if (next) {
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dst_garbage.list = NULL;
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spin_unlock_bh(&dst_garbage.lock);
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goto loop;
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}
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last->next = NULL;
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dst_busy_list = head.next;
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if (!dst_busy_list)
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dst_garbage.timer_inc = DST_GC_MAX;
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else {
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/*
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* if we freed less than 1/10 of delayed entries,
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* we can sleep longer.
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*/
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if (work_performed <= delayed/10) {
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dst_garbage.timer_expires += dst_garbage.timer_inc;
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if (dst_garbage.timer_expires > DST_GC_MAX)
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dst_garbage.timer_expires = DST_GC_MAX;
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dst_garbage.timer_inc += DST_GC_INC;
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} else {
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dst_garbage.timer_inc = DST_GC_INC;
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dst_garbage.timer_expires = DST_GC_MIN;
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}
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expires = dst_garbage.timer_expires;
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/*
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* if the next desired timer is more than 4 seconds in the future
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* then round the timer to whole seconds
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*/
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if (expires > 4*HZ)
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expires = round_jiffies_relative(expires);
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schedule_delayed_work(&dst_gc_work, expires);
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}
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spin_unlock_bh(&dst_garbage.lock);
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mutex_unlock(&dst_gc_mutex);
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#if RT_CACHE_DEBUG >= 2
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elapsed = ktime_to_timespec(ktime_sub(ktime_get(), time_start));
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printk(KERN_DEBUG "dst_total: %d delayed: %d work_perf: %d"
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" expires: %lu elapsed: %lu us\n",
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atomic_read(&dst_total), delayed, work_performed,
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expires,
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elapsed.tv_sec * USEC_PER_SEC + elapsed.tv_nsec / NSEC_PER_USEC);
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#endif
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}
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int dst_discard(struct sk_buff *skb)
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{
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kfree_skb(skb);
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return 0;
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}
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EXPORT_SYMBOL(dst_discard);
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void * dst_alloc(struct dst_ops * ops)
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{
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struct dst_entry * dst;
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if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
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if (ops->gc(ops))
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return NULL;
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}
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dst = kmem_cache_zalloc(ops->kmem_cachep, GFP_ATOMIC);
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if (!dst)
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return NULL;
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atomic_set(&dst->__refcnt, 0);
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dst->ops = ops;
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dst->lastuse = jiffies;
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dst->path = dst;
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dst->input = dst->output = dst_discard;
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#if RT_CACHE_DEBUG >= 2
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atomic_inc(&dst_total);
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#endif
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atomic_inc(&ops->entries);
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return dst;
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}
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static void ___dst_free(struct dst_entry * dst)
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{
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/* The first case (dev==NULL) is required, when
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protocol module is unloaded.
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*/
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if (dst->dev == NULL || !(dst->dev->flags&IFF_UP)) {
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dst->input = dst->output = dst_discard;
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}
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dst->obsolete = 2;
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}
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void __dst_free(struct dst_entry * dst)
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{
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spin_lock_bh(&dst_garbage.lock);
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___dst_free(dst);
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dst->next = dst_garbage.list;
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dst_garbage.list = dst;
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if (dst_garbage.timer_inc > DST_GC_INC) {
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dst_garbage.timer_inc = DST_GC_INC;
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dst_garbage.timer_expires = DST_GC_MIN;
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schedule_delayed_work(&dst_gc_work, dst_garbage.timer_expires);
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}
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spin_unlock_bh(&dst_garbage.lock);
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}
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struct dst_entry *dst_destroy(struct dst_entry * dst)
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{
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struct dst_entry *child;
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struct neighbour *neigh;
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struct hh_cache *hh;
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smp_rmb();
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again:
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neigh = dst->neighbour;
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hh = dst->hh;
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child = dst->child;
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dst->hh = NULL;
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if (hh && atomic_dec_and_test(&hh->hh_refcnt))
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kfree(hh);
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if (neigh) {
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dst->neighbour = NULL;
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neigh_release(neigh);
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}
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atomic_dec(&dst->ops->entries);
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if (dst->ops->destroy)
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dst->ops->destroy(dst);
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if (dst->dev)
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dev_put(dst->dev);
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#if RT_CACHE_DEBUG >= 2
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atomic_dec(&dst_total);
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#endif
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kmem_cache_free(dst->ops->kmem_cachep, dst);
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dst = child;
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if (dst) {
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int nohash = dst->flags & DST_NOHASH;
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if (atomic_dec_and_test(&dst->__refcnt)) {
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/* We were real parent of this dst, so kill child. */
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if (nohash)
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goto again;
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} else {
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/* Child is still referenced, return it for freeing. */
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if (nohash)
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return dst;
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/* Child is still in his hash table */
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}
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}
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return NULL;
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}
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/* Dirty hack. We did it in 2.2 (in __dst_free),
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* we have _very_ good reasons not to repeat
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* this mistake in 2.3, but we have no choice
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* now. _It_ _is_ _explicit_ _deliberate_
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* _race_ _condition_.
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*
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* Commented and originally written by Alexey.
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*/
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static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
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int unregister)
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{
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if (dst->ops->ifdown)
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dst->ops->ifdown(dst, dev, unregister);
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if (dev != dst->dev)
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return;
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if (!unregister) {
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dst->input = dst->output = dst_discard;
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} else {
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dst->dev = dst->dev->nd_net->loopback_dev;
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dev_hold(dst->dev);
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dev_put(dev);
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if (dst->neighbour && dst->neighbour->dev == dev) {
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dst->neighbour->dev = dst->dev;
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dev_hold(dst->dev);
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dev_put(dev);
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}
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}
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}
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static int dst_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
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{
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struct net_device *dev = ptr;
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struct dst_entry *dst, *last = NULL;
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switch (event) {
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case NETDEV_UNREGISTER:
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case NETDEV_DOWN:
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mutex_lock(&dst_gc_mutex);
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for (dst = dst_busy_list; dst; dst = dst->next) {
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last = dst;
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dst_ifdown(dst, dev, event != NETDEV_DOWN);
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}
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spin_lock_bh(&dst_garbage.lock);
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dst = dst_garbage.list;
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dst_garbage.list = NULL;
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spin_unlock_bh(&dst_garbage.lock);
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if (last)
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last->next = dst;
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else
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dst_busy_list = dst;
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for (; dst; dst = dst->next) {
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dst_ifdown(dst, dev, event != NETDEV_DOWN);
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}
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mutex_unlock(&dst_gc_mutex);
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break;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block dst_dev_notifier = {
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.notifier_call = dst_dev_event,
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};
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void __init dst_init(void)
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{
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register_netdevice_notifier(&dst_dev_notifier);
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}
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EXPORT_SYMBOL(__dst_free);
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EXPORT_SYMBOL(dst_alloc);
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EXPORT_SYMBOL(dst_destroy);
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