path: root/net/core/rtnetlink.c
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/core/rtnetlink.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/core/rtnetlink.c')
1 files changed, 5 insertions, 7 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d7c4bb4b1820..296331257195 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1007,10 +1007,11 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
s_h = cb->args[0];
s_idx = cb->args[1];
+ rcu_read_lock();
for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
idx = 0;
head = &net->dev_index_head[h];
- hlist_for_each_entry(dev, node, head, index_hlist) {
+ hlist_for_each_entry_rcu(dev, node, head, index_hlist) {
if (idx < s_idx)
goto cont;
if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
@@ -1023,6 +1024,7 @@ cont:
+ rcu_read_unlock();
cb->args[1] = idx;
cb->args[0] = h;
@@ -1879,7 +1881,6 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
int min_len;
int family;
int type;
- int err;
type = nlh->nlmsg_type;
if (type > RTM_MAX)
@@ -1906,11 +1907,8 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (dumpit == NULL)
- __rtnl_unlock();
rtnl = net->rtnl;
- err = netlink_dump_start(rtnl, skb, nlh, dumpit, NULL);
- rtnl_lock();
- return err;
+ return netlink_dump_start(rtnl, skb, nlh, dumpit, NULL);
memset(rta_buf, 0, (rtattr_max * sizeof(struct rtattr *)));
@@ -1980,7 +1978,7 @@ static int __net_init rtnetlink_net_init(struct net *net)
struct sock *sk;
sk = netlink_kernel_create(net, NETLINK_ROUTE, RTNLGRP_MAX,
- rtnetlink_rcv, &rtnl_mutex, THIS_MODULE);
+ rtnetlink_rcv, NULL, THIS_MODULE);
if (!sk)
return -ENOMEM;
net->rtnl = sk;

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