diff options
| 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/phonet | |
| parent | dcfd9cdc1222f14d6180514e533289493a0716fb (diff) | |
| download | lwn-e67f88dd12f610da98ca838822f2c9b4e7c6100e.tar.gz lwn-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/phonet')
| -rw-r--r-- | net/phonet/pn_dev.c | 6 | ||||
| -rw-r--r-- | net/phonet/pn_netlink.c | 4 |
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) continue; @@ -279,6 +280,7 @@ static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb) } out: + rcu_read_unlock(); cb->args[0] = addr_idx; cb->args[1] = 0; |