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/phonet/pn_dev.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'net/phonet/pn_dev.c') diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c index 947038ddd04c..47b3452675b6 100644 --- a/net/phonet/pn_dev.c +++ b/net/phonet/pn_dev.c @@ -426,18 +426,14 @@ int phonet_route_del(struct net_device *dev, u8 daddr) return 0; } -struct net_device *phonet_route_get(struct net *net, u8 daddr) +struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr) { struct phonet_net *pnn = phonet_pernet(net); struct phonet_routes *routes = &pnn->routes; struct net_device *dev; - ASSERT_RTNL(); /* no need to hold the device */ - daddr >>= 2; - rcu_read_lock(); dev = rcu_dereference(routes->table[daddr]); - rcu_read_unlock(); return dev; } -- cgit v1.2.3-59-g8ed1b