[PATCH net-next 6/6] ipv6: avoid cache line dirtying in ipv6_dev_get_saddr()
From: Eric Dumazet <edumazet@google.com>
Date: 2017-10-08 02:30:50
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
By extending the rcu section a bit, we can avoid these very expensive in6_ifa_put()/in6_ifa_hold() calls done in __ipv6_dev_get_saddr() and ipv6_dev_get_saddr() Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/ipv6/addrconf.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 20c3ca777529fc49ebf749ca6f7d8c2451258d55..cab3faad2bf1354c1241a11ac27178ea675aed55 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c@@ -1608,11 +1608,6 @@ static int __ipv6_dev_get_saddr(struct net *net, } break; } else if (minihiscore < miniscore) { - if (hiscore->ifa) - in6_ifa_put(hiscore->ifa); - - in6_ifa_hold(score->ifa); - swap(hiscore, score); hiscore_idx = 1 - hiscore_idx;
@@ -1660,6 +1655,7 @@ int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev, int dst_type; bool use_oif_addr = false; int hiscore_idx = 0; + int ret = 0; dst_type = __ipv6_addr_type(daddr); dst.addr = daddr;
@@ -1735,15 +1731,14 @@ int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev, } out: - rcu_read_unlock(); - hiscore = &scores[hiscore_idx]; if (!hiscore->ifa) - return -EADDRNOTAVAIL; + ret = -EADDRNOTAVAIL; + else + *saddr = hiscore->ifa->addr; - *saddr = hiscore->ifa->addr; - in6_ifa_put(hiscore->ifa); - return 0; + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL(ipv6_dev_get_saddr);
--
2.14.2.920.gcf0c67979c-goog