From e67f88dd12f610da98ca838822f2c9b4e7c6100e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 27 Apr 2011 22:56:07 +0000 Subject: 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 Cc: Patrick McHardy Cc: Remi Denis-Courmont Acked-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/bridge/br_netlink.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'net/bridge/br_netlink.c') 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; -- cgit v1.2.1