ipvs: free ip_vs_dest structs when refcnt=0
Currently, the ip_vs_dest cache frees ip_vs_dest objects when their reference count becomes < 0. Aside from not being semantically sound, this is problematic for the new type refcount_t, which will be introduced shortly in a separate patch. refcount_t is the new kernel type for holding reference counts, and provides overflow protection and a constrained interface relative to atomic_t (the type currently being used for kernel reference counts). Per Julian Anastasov: "The problem is that dest_trash currently holds deleted dests (unlinked from RCU lists) with refcnt=0." Changing dest_trash to hold dest with refcnt=1 will allow us to free ip_vs_dest structs when their refcnt=0, in ip_vs_dest_put_and_free(). Signed-off-by: David Windsor <dwindsor@gmail.com> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ -1421,7 +1421,7 @@ static inline void ip_vs_dest_put(struct ip_vs_dest *dest)
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static inline void ip_vs_dest_put_and_free(struct ip_vs_dest *dest)
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{
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if (atomic_dec_return(&dest->refcnt) < 0)
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if (atomic_dec_and_test(&dest->refcnt))
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kfree(dest);
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}
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@ -711,7 +711,6 @@ ip_vs_trash_get_dest(struct ip_vs_service *svc, int dest_af,
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dest->vport == svc->port))) {
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/* HIT */
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list_del(&dest->t_list);
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ip_vs_dest_hold(dest);
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goto out;
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}
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}
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@ -741,7 +740,7 @@ static void ip_vs_dest_free(struct ip_vs_dest *dest)
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* When the ip_vs_control_clearup is activated by ipvs module exit,
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* the service tables must have been flushed and all the connections
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* are expired, and the refcnt of each destination in the trash must
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* be 0, so we simply release them here.
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* be 1, so we simply release them here.
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*/
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static void ip_vs_trash_cleanup(struct netns_ipvs *ipvs)
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{
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@ -1080,11 +1079,10 @@ static void __ip_vs_del_dest(struct netns_ipvs *ipvs, struct ip_vs_dest *dest,
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if (list_empty(&ipvs->dest_trash) && !cleanup)
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mod_timer(&ipvs->dest_trash_timer,
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jiffies + (IP_VS_DEST_TRASH_PERIOD >> 1));
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/* dest lives in trash without reference */
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/* dest lives in trash with reference */
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list_add(&dest->t_list, &ipvs->dest_trash);
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dest->idle_start = 0;
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spin_unlock_bh(&ipvs->dest_trash_lock);
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ip_vs_dest_put(dest);
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}
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@ -1160,7 +1158,7 @@ static void ip_vs_dest_trash_expire(unsigned long data)
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spin_lock(&ipvs->dest_trash_lock);
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list_for_each_entry_safe(dest, next, &ipvs->dest_trash, t_list) {
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if (atomic_read(&dest->refcnt) > 0)
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if (atomic_read(&dest->refcnt) > 1)
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continue;
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if (dest->idle_start) {
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if (time_before(now, dest->idle_start +
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