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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-04-27 22:56:07 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-05-02 15:26:28 -0700 |
| commit | e67f88dd12f610da98ca838822f2c9b4e7c6100e (patch) | |
| tree | 6cf01b794984aaad97b6e6ff6e5103bc48d68191 /net/ipv6/ip6_fib.c | |
| parent | dcfd9cdc1222f14d6180514e533289493a0716fb (diff) | |
| download | blackbird-op-linux-e67f88dd12f610da98ca838822f2c9b4e7c6100e.tar.gz blackbird-op-linux-e67f88dd12f610da98ca838822f2c9b4e7c6100e.zip | |
net: dont hold rtnl mutex during netlink dump callbacks
Four years ago, Patrick made a change to hold rtnl mutex during netlink
dump callbacks.
I believe it was a wrong move. This slows down concurrent dumps, making
good old /proc/net/ files faster than rtnetlink in some situations.
This occurred to me because one "ip link show dev ..." was _very_ slow
on a workload adding/removing network devices in background.
All dump callbacks are able to use RCU locking now, so this patch does
roughly a revert of commits :
1c2d670f366 : [RTNETLINK]: Hold rtnl_mutex during netlink dump callbacks
6313c1e0992 : [RTNETLINK]: Remove unnecessary locking in dump callbacks
This let writers fight for rtnl mutex and readers going full speed.
It also takes care of phonet : phonet_route_get() is now called from rcu
read section. I renamed it to phonet_route_get_rcu()
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ip6_fib.c')
| -rw-r--r-- | net/ipv6/ip6_fib.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index dd88df0a5d7f..4076a0b14b20 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -394,10 +394,11 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) arg.net = net; w->args = &arg; + rcu_read_lock(); for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) { e = 0; head = &net->ipv6.fib_table_hash[h]; - hlist_for_each_entry(tb, node, head, tb6_hlist) { + hlist_for_each_entry_rcu(tb, node, head, tb6_hlist) { if (e < s_e) goto next; res = fib6_dump_table(tb, skb, cb); @@ -408,6 +409,7 @@ next: } } out: + rcu_read_unlock(); cb->args[1] = e; cb->args[0] = h; |
