ipv4: per cpu uncached list
RAW sockets with hdrinc suffer from contention on rt_uncached_lock
spinlock.
One solution is to use percpu lists, since most routes are destroyed
by the cpu that created them.
It is unclear why we even have to put these routes in uncached_list,
as all outgoing packets should be freed when a device is dismantled.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: caacf05e5ad1 ("ipv4: Properly purge netdev references on uncached routes.")
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 6a2155b..ce112d0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1325,14 +1325,22 @@
return ret;
}
-static DEFINE_SPINLOCK(rt_uncached_lock);
-static LIST_HEAD(rt_uncached_list);
+struct uncached_list {
+ spinlock_t lock;
+ struct list_head head;
+};
+
+static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
static void rt_add_uncached_list(struct rtable *rt)
{
- spin_lock_bh(&rt_uncached_lock);
- list_add_tail(&rt->rt_uncached, &rt_uncached_list);
- spin_unlock_bh(&rt_uncached_lock);
+ struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
+
+ rt->rt_uncached_list = ul;
+
+ spin_lock_bh(&ul->lock);
+ list_add_tail(&rt->rt_uncached, &ul->head);
+ spin_unlock_bh(&ul->lock);
}
static void ipv4_dst_destroy(struct dst_entry *dst)
@@ -1340,27 +1348,32 @@
struct rtable *rt = (struct rtable *) dst;
if (!list_empty(&rt->rt_uncached)) {
- spin_lock_bh(&rt_uncached_lock);
+ struct uncached_list *ul = rt->rt_uncached_list;
+
+ spin_lock_bh(&ul->lock);
list_del(&rt->rt_uncached);
- spin_unlock_bh(&rt_uncached_lock);
+ spin_unlock_bh(&ul->lock);
}
}
void rt_flush_dev(struct net_device *dev)
{
- if (!list_empty(&rt_uncached_list)) {
- struct net *net = dev_net(dev);
- struct rtable *rt;
+ struct net *net = dev_net(dev);
+ struct rtable *rt;
+ int cpu;
- spin_lock_bh(&rt_uncached_lock);
- list_for_each_entry(rt, &rt_uncached_list, rt_uncached) {
+ for_each_possible_cpu(cpu) {
+ struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
+
+ spin_lock_bh(&ul->lock);
+ list_for_each_entry(rt, &ul->head, rt_uncached) {
if (rt->dst.dev != dev)
continue;
rt->dst.dev = net->loopback_dev;
dev_hold(rt->dst.dev);
dev_put(dev);
}
- spin_unlock_bh(&rt_uncached_lock);
+ spin_unlock_bh(&ul->lock);
}
}
@@ -2717,6 +2730,7 @@
int __init ip_rt_init(void)
{
int rc = 0;
+ int cpu;
ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
if (!ip_idents)
@@ -2724,6 +2738,12 @@
prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
+ for_each_possible_cpu(cpu) {
+ struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
+
+ INIT_LIST_HEAD(&ul->head);
+ spin_lock_init(&ul->lock);
+ }
#ifdef CONFIG_IP_ROUTE_CLASSID
ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
if (!ip_rt_acct)