Commit 7c28bd0b authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

rtnetlink: speedup rtnl_dump_ifinfo()

When handling large number of netdevice, rtnl_dump_ifinfo()
is very slow because it has O(N^2) complexity.

Instead of scanning one single list, we can use the 256 sub lists
of the dev_index hash table.

This considerably speedups "ip link" operations
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8d5b2c08
......@@ -28,6 +28,10 @@ struct ctl_table_header;
struct net_generic;
struct sock;
#define NETDEV_HASHBITS 8
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)
struct net {
atomic_t count; /* To decided when the network
* namespace should be freed.
......
......@@ -193,18 +193,15 @@ static struct list_head ptype_all __read_mostly; /* Taps */
DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock);
#define NETDEV_HASHBITS 8
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)
static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
{
unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ));
return &net->dev_name_head[hash & ((1 << NETDEV_HASHBITS) - 1)];
return &net->dev_name_head[hash & (NETDEV_HASHENTRIES - 1)];
}
static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
{
return &net->dev_index_head[ifindex & ((1 << NETDEV_HASHBITS) - 1)];
return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
}
/* Device list insertion */
......
......@@ -682,22 +682,33 @@ nla_put_failure:
static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
int idx;
int s_idx = cb->args[0];
int h, s_h;
int idx = 0, s_idx;
struct net_device *dev;
idx = 0;
for_each_netdev(net, dev) {
if (idx < s_idx)
goto cont;
if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, 0, NLM_F_MULTI) <= 0)
break;
struct hlist_head *head;
struct hlist_node *node;
s_h = cb->args[0];
s_idx = cb->args[1];
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) {
if (idx < s_idx)
goto cont;
if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, 0,
NLM_F_MULTI) <= 0)
goto out;
cont:
idx++;
idx++;
}
}
cb->args[0] = idx;
out:
cb->args[1] = idx;
cb->args[0] = h;
return skb->len;
}
......
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