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authorJulian Anastasov <ja@ssi.bg>2013-09-12 11:21:07 +0300
committerSimon Horman <horms@verge.net.au>2013-09-18 14:39:03 -0500
commitbcbde4c0a7556cca72874c5e1efa4dccb5198a2b (patch)
tree73e5f985bbcd5a976c26dd75e4672ac2b70b9270 /include
parentc16526a7b99c1c28e9670a8c8e3dbcf741bb32be (diff)
downloadlinux-bcbde4c0a7556cca72874c5e1efa4dccb5198a2b.tar.bz2
ipvs: make the service replacement more robust
commit 578bc3ef1e473a ("ipvs: reorganize dest trash") added IP_VS_DEST_STATE_REMOVING flag and RCU callback named ip_vs_dest_wait_readers() to keep dests and services after removal for at least a RCU grace period. But we have the following corner cases: - we can not reuse the same dest if its service is removed while IP_VS_DEST_STATE_REMOVING is still set because another dest removal in the first grace period can not extend this period. It can happen when ipvsadm -C && ipvsadm -R is used. - dest->svc can be replaced but ip_vs_in_stats() and ip_vs_out_stats() have no explicit read memory barriers when accessing dest->svc. It can happen that dest->svc was just freed (replaced) while we use it to update the stats. We solve the problems as follows: - IP_VS_DEST_STATE_REMOVING is removed and we ensure a fixed idle period for the dest (IP_VS_DEST_TRASH_PERIOD). idle_start will remember when for first time after deletion we noticed dest->refcnt=0. Later, the connections can grab a reference while in RCU grace period but if refcnt becomes 0 we can safely free the dest and its svc. - dest->svc becomes RCU pointer. As result, we add explicit RCU locking in ip_vs_in_stats() and ip_vs_out_stats(). - __ip_vs_unbind_svc is renamed to __ip_vs_svc_put(), it now can free the service immediately or after a RCU grace period. dest->svc is not set to NULL anymore. As result, unlinked dests and their services are freed always after IP_VS_DEST_TRASH_PERIOD period, unused services are freed after a RCU grace period. Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>
Diffstat (limited to 'include')
-rw-r--r--include/net/ip_vs.h7
1 files changed, 2 insertions, 5 deletions
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index fe782ed2fe72..9c4d37ec45a1 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -723,8 +723,6 @@ struct ip_vs_dest_dst {
struct rcu_head rcu_head;
};
-/* In grace period after removing */
-#define IP_VS_DEST_STATE_REMOVING 0x01
/*
* The real server destination forwarding entry
* with ip address, port number, and so on.
@@ -742,7 +740,7 @@ struct ip_vs_dest {
atomic_t refcnt; /* reference counter */
struct ip_vs_stats stats; /* statistics */
- unsigned long state; /* state flags */
+ unsigned long idle_start; /* start time, jiffies */
/* connection counters and thresholds */
atomic_t activeconns; /* active connections */
@@ -756,14 +754,13 @@ struct ip_vs_dest {
struct ip_vs_dest_dst __rcu *dest_dst; /* cached dst info */
/* for virtual service */
- struct ip_vs_service *svc; /* service it belongs to */
+ struct ip_vs_service __rcu *svc; /* service it belongs to */
__u16 protocol; /* which protocol (TCP/UDP) */
__be16 vport; /* virtual port number */
union nf_inet_addr vaddr; /* virtual IP address */
__u32 vfwmark; /* firewall mark of service */
struct list_head t_list; /* in dest_trash */
- struct rcu_head rcu_head;
unsigned int in_rs_table:1; /* we are in rs_table */
};