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| author | Eric Dumazet <edumazet@google.com> | 2018-03-07 08:43:19 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-07 18:13:41 -0500 |
| commit | a366e300ae9fc466d333e6d8f2bc5d58ed248041 (patch) | |
| tree | 689aef7cbe9b1df29666ab6a67439a81f2edc7ab /net/ipv6/ip6mr.c | |
| parent | 3f6be0ebdeb2255534664c4ececc2eac1d5dcb30 (diff) | |
| download | lwn-a366e300ae9fc466d333e6d8f2bc5d58ed248041.tar.gz lwn-a366e300ae9fc466d333e6d8f2bc5d58ed248041.zip | |
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.c | 6 |
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; } |