forked from Minki/linux
a4c2fd7f78
DST_NOCACHE flag check has been removed from dst_release() and dst_hold_safe() in a previous patch because all the dst are now ref counted properly and can be released based on refcnt only. Looking at the rest of the DST_NOCACHE use, all of them can now be removed or replaced with other checks. So this patch gets rid of all the DST_NOCACHE usage and remove this flag completely. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
319 lines
7.6 KiB
C
319 lines
7.6 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/lwtunnel.h>
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#include <net/dst.h>
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#include <net/dst_metadata.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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int dst_discard_out(struct net *net, struct sock *sk, 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_out);
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const struct dst_metrics dst_default_metrics = {
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/* This initializer is needed to force linker to place this variable
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* into const section. Otherwise it might end into bss section.
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* We really want to avoid false sharing on this variable, and catch
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* any writes on it.
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*/
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.refcnt = ATOMIC_INIT(1),
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};
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void dst_init(struct dst_entry *dst, struct dst_ops *ops,
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struct net_device *dev, int initial_ref, int initial_obsolete,
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unsigned short flags)
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{
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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.metrics, true);
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dst->expires = 0UL;
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dst->path = dst;
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dst->from = 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_out;
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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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dst->lwtstate = NULL;
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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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}
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EXPORT_SYMBOL(dst_init);
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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, unsigned short 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_init(dst, ops, dev, initial_ref, initial_obsolete, flags);
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return dst;
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}
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EXPORT_SYMBOL(dst_alloc);
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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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smp_rmb();
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child = dst->child;
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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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lwtstate_put(dst->lwtstate);
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if (dst->flags & DST_METADATA)
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metadata_dst_free((struct metadata_dst *)dst);
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else
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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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dst_release_immediate(dst);
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return NULL;
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}
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EXPORT_SYMBOL(dst_destroy);
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static void dst_destroy_rcu(struct rcu_head *head)
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{
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struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
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dst = dst_destroy(dst);
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}
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/* Operations to mark dst as DEAD and clean up the net device referenced
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* by dst:
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* 1. put the dst under loopback interface and discard all tx/rx packets
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* on this route.
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* 2. release the net_device
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* This function should be called when removing routes from the fib tree
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* in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
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* make the next dst_ops->check() fail.
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*/
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void dst_dev_put(struct dst_entry *dst)
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{
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struct net_device *dev = dst->dev;
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dst->obsolete = DST_OBSOLETE_DEAD;
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if (dst->ops->ifdown)
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dst->ops->ifdown(dst, dev, true);
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dst->input = dst_discard;
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dst->output = dst_discard_out;
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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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}
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EXPORT_SYMBOL(dst_dev_put);
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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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if (unlikely(newrefcnt < 0))
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net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
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__func__, dst, newrefcnt);
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if (!newrefcnt)
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call_rcu(&dst->rcu_head, dst_destroy_rcu);
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}
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}
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EXPORT_SYMBOL(dst_release);
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void dst_release_immediate(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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if (unlikely(newrefcnt < 0))
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net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
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__func__, dst, newrefcnt);
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if (!newrefcnt)
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dst_destroy(dst);
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}
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}
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EXPORT_SYMBOL(dst_release_immediate);
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u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
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{
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struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC);
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if (p) {
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struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);
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unsigned long prev, new;
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atomic_set(&p->refcnt, 1);
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memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));
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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 = (struct dst_metrics *)__DST_METRICS_PTR(prev);
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if (prev & DST_METRICS_READ_ONLY)
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p = NULL;
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} else if (prev & DST_METRICS_REFCOUNTED) {
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if (atomic_dec_and_test(&old_p->refcnt))
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kfree(old_p);
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}
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}
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BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0);
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return (u32 *)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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static struct dst_ops md_dst_ops = {
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.family = AF_UNSPEC,
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};
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static int dst_md_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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WARN_ONCE(1, "Attempting to call output on metadata dst\n");
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kfree_skb(skb);
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return 0;
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}
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static int dst_md_discard(struct sk_buff *skb)
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{
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WARN_ONCE(1, "Attempting to call input on metadata dst\n");
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kfree_skb(skb);
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return 0;
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}
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static void __metadata_dst_init(struct metadata_dst *md_dst, u8 optslen)
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{
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struct dst_entry *dst;
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dst = &md_dst->dst;
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dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
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DST_METADATA | DST_NOCOUNT);
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dst->input = dst_md_discard;
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dst->output = dst_md_discard_out;
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memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
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}
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struct metadata_dst *metadata_dst_alloc(u8 optslen, gfp_t flags)
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{
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struct metadata_dst *md_dst;
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md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
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if (!md_dst)
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return NULL;
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__metadata_dst_init(md_dst, optslen);
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return md_dst;
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}
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EXPORT_SYMBOL_GPL(metadata_dst_alloc);
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void metadata_dst_free(struct metadata_dst *md_dst)
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{
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#ifdef CONFIG_DST_CACHE
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dst_cache_destroy(&md_dst->u.tun_info.dst_cache);
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#endif
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kfree(md_dst);
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}
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struct metadata_dst __percpu *metadata_dst_alloc_percpu(u8 optslen, gfp_t flags)
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{
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int cpu;
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struct metadata_dst __percpu *md_dst;
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md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
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__alignof__(struct metadata_dst), flags);
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if (!md_dst)
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return NULL;
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for_each_possible_cpu(cpu)
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__metadata_dst_init(per_cpu_ptr(md_dst, cpu), optslen);
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return md_dst;
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}
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EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);
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