path: root/net/phonet
diff options
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/phonet
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/phonet')
2 files changed, 4 insertions, 6 deletions
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;
diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c
index 58b3b1f991ed..438accb7a5a8 100644
--- a/net/phonet/pn_netlink.c
+++ b/net/phonet/pn_netlink.c
@@ -264,10 +264,11 @@ static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
struct net *net = sock_net(skb->sk);
u8 addr, addr_idx = 0, addr_start_idx = cb->args[0];
+ rcu_read_lock();
for (addr = 0; addr < 64; addr++) {
struct net_device *dev;
- dev = phonet_route_get(net, addr << 2);
+ dev = phonet_route_get_rcu(net, addr << 2);
if (!dev)
@@ -279,6 +280,7 @@ static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
+ rcu_read_unlock();
cb->args[0] = addr_idx;
cb->args[1] = 0;

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