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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/decnet/dn_dev.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/decnet/dn_dev.c')
-rw-r--r--net/decnet/dn_dev.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index 0dcaa903e00e..404fa1591027 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -752,7 +752,8 @@ static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
skip_naddr = cb->args[1];
idx = 0;
- for_each_netdev(&init_net, dev) {
+ rcu_read_lock();
+ for_each_netdev_rcu(&init_net, dev) {
if (idx < skip_ndevs)
goto cont;
else if (idx > skip_ndevs) {
@@ -761,11 +762,11 @@ static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
skip_naddr = 0;
}
- if ((dn_db = rtnl_dereference(dev->dn_ptr)) == NULL)
+ if ((dn_db = rcu_dereference(dev->dn_ptr)) == NULL)
goto cont;
- for (ifa = rtnl_dereference(dn_db->ifa_list), dn_idx = 0; ifa;
- ifa = rtnl_dereference(ifa->ifa_next), dn_idx++) {
+ for (ifa = rcu_dereference(dn_db->ifa_list), dn_idx = 0; ifa;
+ ifa = rcu_dereference(ifa->ifa_next), dn_idx++) {
if (dn_idx < skip_naddr)
continue;
@@ -778,6 +779,7 @@ cont:
idx++;
}
done:
+ rcu_read_unlock();
cb->args[0] = idx;
cb->args[1] = dn_idx;

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