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author | Julian Anastasov <ja@ssi.bg> | 2013-09-12 11:21:07 +0300 |
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committer | Simon Horman <horms@verge.net.au> | 2013-09-18 14:39:03 -0500 |
commit | bcbde4c0a7556cca72874c5e1efa4dccb5198a2b (patch) | |
tree | 73e5f985bbcd5a976c26dd75e4672ac2b70b9270 /include/net/ip_vs.h | |
parent | c16526a7b99c1c28e9670a8c8e3dbcf741bb32be (diff) | |
download | linux-stable-bcbde4c0a7556cca72874c5e1efa4dccb5198a2b.tar.gz linux-stable-bcbde4c0a7556cca72874c5e1efa4dccb5198a2b.tar.bz2 linux-stable-bcbde4c0a7556cca72874c5e1efa4dccb5198a2b.zip |
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/net/ip_vs.h')
-rw-r--r-- | include/net/ip_vs.h | 7 |
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 */ }; |