diff options
Diffstat (limited to 'net/netfilter/ipvs/ip_vs_sh.c')
-rw-r--r-- | net/netfilter/ipvs/ip_vs_sh.c | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c index 3588fae..cc65b2f 100644 --- a/net/netfilter/ipvs/ip_vs_sh.c +++ b/net/netfilter/ipvs/ip_vs_sh.c @@ -115,27 +115,46 @@ ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s, } -/* As ip_vs_sh_get, but with fallback if selected server is unavailable */ +/* As ip_vs_sh_get, but with fallback if selected server is unavailable + * + * The fallback strategy loops around the table starting from a "random" + * point (in fact, it is chosen to be the original hash value to make the + * algorithm deterministic) to find a new server. + */ static inline struct ip_vs_dest * ip_vs_sh_get_fallback(struct ip_vs_service *svc, struct ip_vs_sh_state *s, const union nf_inet_addr *addr, __be16 port) { - unsigned int offset; - unsigned int hash; + unsigned int offset, roffset; + unsigned int hash, ihash; struct ip_vs_dest *dest; + /* first try the dest it's supposed to go to */ + ihash = ip_vs_sh_hashkey(svc->af, addr, port, 0); + dest = rcu_dereference(s->buckets[ihash].dest); + if (!dest) + return NULL; + if (!is_unavailable(dest)) + return dest; + + IP_VS_DBG_BUF(6, "SH: selected unavailable server %s:%d, reselecting", + IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port)); + + /* if the original dest is unavailable, loop around the table + * starting from ihash to find a new dest + */ for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) { - hash = ip_vs_sh_hashkey(svc->af, addr, port, offset); + roffset = (offset + ihash) % IP_VS_SH_TAB_SIZE; + hash = ip_vs_sh_hashkey(svc->af, addr, port, roffset); dest = rcu_dereference(s->buckets[hash].dest); if (!dest) break; - if (is_unavailable(dest)) - IP_VS_DBG_BUF(6, "SH: selected unavailable server " - "%s:%d (offset %d)", - IP_VS_DBG_ADDR(svc->af, &dest->addr), - ntohs(dest->port), offset); - else + if (!is_unavailable(dest)) return dest; + IP_VS_DBG_BUF(6, "SH: selected unavailable " + "server %s:%d (offset %d), reselecting", + IP_VS_DBG_ADDR(svc->af, &dest->addr), + ntohs(dest->port), roffset); } return NULL; |