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authorEric Dumazet <edumazet@google.com>2018-03-07 08:43:19 -0800
committerDavid S. Miller <davem@davemloft.net>2018-03-07 18:13:41 -0500
commita366e300ae9fc466d333e6d8f2bc5d58ed248041 (patch)
tree689aef7cbe9b1df29666ab6a67439a81f2edc7ab /net/ipv6/ip6mr.c
parent3f6be0ebdeb2255534664c4ececc2eac1d5dcb30 (diff)
ip6mr: remove synchronize_rcu() in favor of SOCK_RCU_FREE
Kirill found that recently added synchronize_rcu() call in ip6mr_sk_done() was slowing down netns dismantle and posted a patch to use it only if the socket was found. I instead suggested to get rid of this call, and use instead SOCK_RCU_FREE We might later change IPv4 side to use the same technique and unify both stacks. IPv4 does not use synchronize_rcu() but has a call_rcu() that could be replaced by SOCK_RCU_FREE. Tested: time for i in {1..1000}; do unshare -n /bin/false;done Before : real 7m18.911s After : real 10.187s Fixes: 8571ab479a6e ("ip6mr: Make mroute_sk rcu-based") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Yuval Mintz <yuvalm@mellanox.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ip6mr.c')
-rw-r--r--net/ipv6/ip6mr.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 2a38f9de45d3..7345bd6c4b7d 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -1443,6 +1443,7 @@ static int ip6mr_sk_init(struct mr_table *mrt, struct sock *sk)
err = -EADDRINUSE;
} else {
rcu_assign_pointer(mrt->mroute_sk, sk);
+ sock_set_flag(sk, SOCK_RCU_FREE);
net->ipv6.devconf_all->mc_forwarding++;
}
write_unlock_bh(&mrt_lock);
@@ -1472,6 +1473,10 @@ int ip6mr_sk_done(struct sock *sk)
if (sk == rtnl_dereference(mrt->mroute_sk)) {
write_lock_bh(&mrt_lock);
RCU_INIT_POINTER(mrt->mroute_sk, NULL);
+ /* Note that mroute_sk had SOCK_RCU_FREE set,
+ * so the RCU grace period before sk freeing
+ * is guaranteed by sk_destruct()
+ */
net->ipv6.devconf_all->mc_forwarding--;
write_unlock_bh(&mrt_lock);
inet6_netconf_notify_devconf(net, RTM_NEWNETCONF,
@@ -1485,7 +1490,6 @@ int ip6mr_sk_done(struct sock *sk)
}
}
rtnl_unlock();
- synchronize_rcu();
return err;
}