[PATCH 2/2] neighbour: make proxy_queue.qlen limit per-device

Alexander Mikhalitsyn
2022-07-29T10:37:22Z

Right now we have a neigh_param PROXY_QLEN which specifies maximum length
of neigh_table->proxy_queue. But in fact, this limitation doesn't work well
because check condition looks like:
tbl->proxy_queue.qlen > NEIGH_VAR(p, PROXY_QLEN)

The problem is that p (struct neigh_parms) is a per-device thing,
but tbl (struct neigh_table) is a system-wide global thing.

It seems reasonable to make proxy_queue limit per-device based.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@kernel.org>
Cc: Yajun Deng <yajun.deng@linux.dev>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: kernel@openvz.org
Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
---
include/net/neighbour.h | 1 +
net/core/neighbour.c | 25 ++++++++++++++++++++++---
2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 87419f7f5421..bc3fbec70d10 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -82,6 +82,7 @@ struct neigh_parms {
struct rcu_head rcu_head;

int reachable_time;
+ int qlen;
int data[NEIGH_VAR_DATA_MAX];
DECLARE_BITMAP(data_state, NEIGH_VAR_DATA_MAX);
};
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 213ec0be800b..d98923e3ff02 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -316,9 +316,19 @@ static void pneigh_queue_purge(struct sk_buff_head *list, struct net *net)
skb = skb_peek(list);
while (skb != NULL) {
struct sk_buff *skb_next = skb_peek_next(skb, list);
- if (net == NULL || net_eq(dev_net(skb->dev), net)) {
+ struct net_device *dev = skb->dev;
+
+ if (!net || net_eq(dev_net(dev), net)) {
+ struct in_device *in_dev;
+
+ rcu_read_lock();
+ in_dev = __in_dev_get_rcu(dev);
+ if (in_dev)
+ in_dev->arp_parms->qlen--;
+ rcu_read_unlock();
__skb_unlink(skb, list);
- dev_put(skb->dev);
+
+ dev_put(dev);
kfree_skb(skb);
}
skb = skb_next;
@@ -1605,8 +1615,15 @@ static void neigh_proxy_process(struct timer_list *t)

if (tdif <= 0) {
struct net_device *dev = skb->dev;
+ struct in_device *in_dev;

+ rcu_read_lock();
+ in_dev = __in_dev_get_rcu(dev);
+ if (in_dev)
+ in_dev->arp_parms->qlen--;
+ rcu_read_unlock();
__skb_unlink(skb, &tbl->proxy_queue);
+
if (tbl->proxy_redo && netif_running(dev)) {
rcu_read_lock();
tbl->proxy_redo(skb);
@@ -1631,7 +1648,7 @@ void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
unsigned long sched_next = jiffies +
prandom_u32_max(NEIGH_VAR(p, PROXY_DELAY));

- if (tbl->proxy_queue.qlen > NEIGH_VAR(p, PROXY_QLEN)) {
+ if (p->qlen > NEIGH_VAR(p, PROXY_QLEN)) {
kfree_skb(skb);
return;
}
@@ -1647,6 +1664,7 @@ void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
skb_dst_drop(skb);
dev_hold(skb->dev);
__skb_queue_tail(&tbl->proxy_queue, skb);
+ p->qlen++;
mod_timer(&tbl->proxy_timer, sched_next);
spin_unlock(&tbl->proxy_queue.lock);
}
@@ -1679,6 +1697,7 @@ struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
refcount_set(&p->refcnt, 1);
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
+ p->qlen = 0;
dev_hold_track(dev, &p->dev_tracker, GFP_KERNEL);
p->dev = dev;
write_pnet(&p->net, net);
@@ -1744,6 +1763,7 @@ void neigh_table_init(int index, struct neigh_table *tbl)
refcount_set(&tbl->parms.refcnt, 1);
tbl->parms.reachable_time =
neigh_rand_reach_time(NEIGH_VAR(&tbl->parms, BASE_REACHABLE_TIME));
+ tbl->parms.qlen = 0;

tbl->stats = alloc_percpu(struct neigh_statistics);
if (!tbl->stats)
--
2.36.1