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authorEric Dumazet <eric.dumazet@gmail.com>2011-04-27 22:56:07 +0000
committerDavid S. Miller <davem@davemloft.net>2011-05-02 15:26:28 -0700
commite67f88dd12f610da98ca838822f2c9b4e7c6100e (patch)
tree6cf01b794984aaad97b6e6ff6e5103bc48d68191 /net/bridge/br_netlink.c
parentdcfd9cdc1222f14d6180514e533289493a0716fb (diff)
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/bridge/br_netlink.c')
-rw-r--r--net/bridge/br_netlink.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 134a2ff6b98b..ffb0dc4cc0e8 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -120,8 +120,9 @@ static int br_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
int idx;
idx = 0;
- for_each_netdev(net, dev) {
- struct net_bridge_port *port = br_port_get_rtnl(dev);
+ rcu_read_lock();
+ for_each_netdev_rcu(net, dev) {
+ struct net_bridge_port *port = br_port_get_rcu(dev);
/* not a bridge port */
if (!port || idx < cb->args[0])
@@ -135,7 +136,7 @@ static int br_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
skip:
++idx;
}
-
+ rcu_read_unlock();
cb->args[0] = idx;
return skb->len;

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