dst: no need to take reference on DST_NOCACHE dsts
Since commit f886497212
("ipv4: fix dst race in sk_dst_get()")
DST_NOCACHE dst_entries get freed by RCU. So there is no need to get a
reference on them when we are in rcu protected sections.
Cc: Eric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
c19be735c9
commit
dbfc4fb7d5
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@ -717,9 +717,6 @@ static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
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skb->_skb_refdst = (unsigned long)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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bool force);
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/**
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* skb_dst_set_noref - sets skb dst, hopefully, without taking reference
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* @skb: buffer
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@ -732,24 +729,8 @@ void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
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*/
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static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
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{
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__skb_dst_set_noref(skb, dst, false);
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}
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/**
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* skb_dst_set_noref_force - sets skb dst, without taking 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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* No reference is taken and no dst_release will be called. While for
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* cached dsts deferred reclaim is a basic feature, for entries that are
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* not cached it is caller's job to guarantee that last dst_release for
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* provided dst happens when nobody uses it, eg. after a RCU grace period.
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*/
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static inline void skb_dst_set_noref_force(struct sk_buff *skb,
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struct dst_entry *dst)
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{
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__skb_dst_set_noref(skb, dst, true);
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WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
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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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@ -327,30 +327,6 @@ void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long 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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* @force: if force is set, use noref version even for DST_NOCACHE entries
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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, bool force)
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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) && !force)) {
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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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@ -343,7 +343,7 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
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skb_dst_drop(skb);
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if (noref) {
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if (!local)
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skb_dst_set_noref_force(skb, &rt->dst);
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skb_dst_set_noref(skb, &rt->dst);
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else
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skb_dst_set(skb, dst_clone(&rt->dst));
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} else
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@ -487,7 +487,7 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
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skb_dst_drop(skb);
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if (noref) {
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if (!local)
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skb_dst_set_noref_force(skb, &rt->dst);
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skb_dst_set_noref(skb, &rt->dst);
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else
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skb_dst_set(skb, dst_clone(&rt->dst));
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} else
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