mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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2721745501
To reflect the fact that a refrence is not obtained to the resulting neighbour entry. Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Roland Dreier <roland@purestorage.com>
420 lines
9.8 KiB
C
420 lines
9.8 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/slab.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 <linux/sched.h>
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#include <linux/prefetch.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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/*
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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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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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cond_resched();
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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
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* future 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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}
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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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const u32 dst_default_metrics[RTAX_MAX];
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void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
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int initial_ref, int initial_obsolete, int flags)
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{
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struct dst_entry *dst;
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if (ops->gc && dst_entries_get_fast(ops) > 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_alloc(ops->kmem_cachep, GFP_ATOMIC);
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if (!dst)
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return NULL;
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dst->child = NULL;
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dst->dev = dev;
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if (dev)
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dev_hold(dev);
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dst->ops = ops;
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dst_init_metrics(dst, dst_default_metrics, true);
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dst->expires = 0UL;
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dst->path = dst;
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RCU_INIT_POINTER(dst->_neighbour, NULL);
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#ifdef CONFIG_XFRM
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dst->xfrm = NULL;
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#endif
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dst->input = dst_discard;
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dst->output = dst_discard;
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dst->error = 0;
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dst->obsolete = initial_obsolete;
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dst->header_len = 0;
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dst->trailer_len = 0;
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#ifdef CONFIG_IP_ROUTE_CLASSID
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dst->tclassid = 0;
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#endif
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atomic_set(&dst->__refcnt, initial_ref);
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dst->__use = 0;
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dst->lastuse = jiffies;
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dst->flags = flags;
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dst->next = NULL;
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if (!(flags & DST_NOCOUNT))
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dst_entries_add(ops, 1);
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return dst;
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}
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EXPORT_SYMBOL(dst_alloc);
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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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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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cancel_delayed_work(&dst_gc_work);
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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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EXPORT_SYMBOL(__dst_free);
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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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smp_rmb();
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again:
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neigh = rcu_dereference_protected(dst->_neighbour, 1);
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child = dst->child;
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if (neigh) {
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RCU_INIT_POINTER(dst->_neighbour, NULL);
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neigh_release(neigh);
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}
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if (!(dst->flags & DST_NOCOUNT))
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dst_entries_add(dst->ops, -1);
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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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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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EXPORT_SYMBOL(dst_destroy);
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void dst_release(struct dst_entry *dst)
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{
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if (dst) {
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int newrefcnt;
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newrefcnt = atomic_dec_return(&dst->__refcnt);
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WARN_ON(newrefcnt < 0);
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if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt) {
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dst = dst_destroy(dst);
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if (dst)
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__dst_free(dst);
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}
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}
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}
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EXPORT_SYMBOL(dst_release);
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u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
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{
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u32 *p = kmalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
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if (p) {
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u32 *old_p = __DST_METRICS_PTR(old);
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unsigned long prev, new;
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memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
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new = (unsigned long) p;
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prev = cmpxchg(&dst->_metrics, old, new);
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if (prev != old) {
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kfree(p);
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p = __DST_METRICS_PTR(prev);
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if (prev & DST_METRICS_READ_ONLY)
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p = NULL;
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}
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}
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return p;
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}
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EXPORT_SYMBOL(dst_cow_metrics_generic);
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/* Caller asserts that dst_metrics_read_only(dst) is false. */
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void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
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{
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unsigned long prev, new;
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new = ((unsigned long) dst_default_metrics) | DST_METRICS_READ_ONLY;
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prev = cmpxchg(&dst->_metrics, old, new);
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if (prev == old)
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kfree(__DST_METRICS_PTR(old));
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}
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EXPORT_SYMBOL(__dst_destroy_metrics_generic);
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/**
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* skb_dst_set_noref - sets skb dst, without a reference
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* @skb: buffer
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* @dst: dst entry
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*
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* Sets skb dst, assuming a reference was not taken on dst
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* skb_dst_drop() should not dst_release() this dst
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*/
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void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
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{
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WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
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/* If dst not in cache, we must take a reference, because
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* dst_release() will destroy dst as soon as its refcount becomes zero
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*/
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if (unlikely(dst->flags & DST_NOCACHE)) {
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dst_hold(dst);
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skb_dst_set(skb, dst);
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} else {
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skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
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}
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}
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EXPORT_SYMBOL(skb_dst_set_noref);
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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 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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struct neighbour *neigh;
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dst->dev = dev_net(dst->dev)->loopback_dev;
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dev_hold(dst->dev);
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dev_put(dev);
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rcu_read_lock();
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neigh = dst_get_neighbour_noref(dst);
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if (neigh && neigh->dev == dev) {
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neigh->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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rcu_read_unlock();
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}
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}
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static int dst_dev_event(struct notifier_block *this, unsigned long event,
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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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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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.priority = -10, /* must be called after other network notifiers */
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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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