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Message-ID: <20250712203515.4099110-6-kuniyu@google.com>
Date: Sat, 12 Jul 2025 20:34:14 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, David Ahern <dsahern@...nel.org>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>,
Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v2 net-next 05/15] neighbour: Split pneigh_lookup().
pneigh_lookup() has ASSERT_RTNL() in the middle of the function, which
is confusing.
When called with the last argument, creat, 0, pneigh_lookup() literally
looks up a proxy neighbour entry. This is the case of the reader path
as the fast path and RTM_GETNEIGH.
pneigh_lookup(), however, creates a pneigh_entry when called with creat 1
from RTM_NEWNEIGH and SIOCSARP, which require RTNL.
Let's split pneigh_lookup() into two functions.
We will convert all the reader paths to RCU, and read_lock_bh(&tbl->lock)
in the new pneigh_lookup() will be dropped.
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
include/net/neighbour.h | 5 +++--
net/core/neighbour.c | 39 +++++++++++++++++++++++++++++----------
net/ipv4/arp.c | 4 ++--
net/ipv6/ip6_output.c | 2 +-
net/ipv6/ndisc.c | 2 +-
5 files changed, 36 insertions(+), 16 deletions(-)
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 7e865b14749d6..7f3d57da5689a 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -376,10 +376,11 @@ unsigned long neigh_rand_reach_time(unsigned long base);
void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
struct sk_buff *skb);
struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
- const void *key, struct net_device *dev,
- int creat);
+ const void *key, struct net_device *dev);
struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl, struct net *net,
const void *key, struct net_device *dev);
+struct pneigh_entry *pneigh_create(struct neigh_table *tbl, struct net *net,
+ const void *key, struct net_device *dev);
int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
struct net_device *dev);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ad79f173e6229..814a45fb1962e 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -28,6 +28,7 @@
#include <net/neighbour.h>
#include <net/arp.h>
#include <net/dst.h>
+#include <net/ip.h>
#include <net/sock.h>
#include <net/netevent.h>
#include <net/netlink.h>
@@ -746,24 +747,44 @@ struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl,
}
EXPORT_SYMBOL_GPL(__pneigh_lookup);
-struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
- struct net *net, const void *pkey,
- struct net_device *dev, int creat)
+struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl,
+ struct net *net, const void *pkey,
+ struct net_device *dev)
+{
+ struct pneigh_entry *n;
+ unsigned int key_len;
+ u32 hash_val;
+
+ key_len = tbl->key_len;
+ hash_val = pneigh_hash(pkey, key_len);
+
+ read_lock_bh(&tbl->lock);
+ n = __pneigh_lookup_1(tbl->phash_buckets[hash_val],
+ net, pkey, key_len, dev);
+ read_unlock_bh(&tbl->lock);
+
+ return n;
+}
+EXPORT_IPV6_MOD(pneigh_lookup);
+
+struct pneigh_entry *pneigh_create(struct neigh_table *tbl,
+ struct net *net, const void *pkey,
+ struct net_device *dev)
{
struct pneigh_entry *n;
unsigned int key_len = tbl->key_len;
u32 hash_val = pneigh_hash(pkey, key_len);
+ ASSERT_RTNL();
+
read_lock_bh(&tbl->lock);
n = __pneigh_lookup_1(tbl->phash_buckets[hash_val],
net, pkey, key_len, dev);
read_unlock_bh(&tbl->lock);
- if (n || !creat)
+ if (n)
goto out;
- ASSERT_RTNL();
-
n = kzalloc(sizeof(*n) + key_len, GFP_KERNEL);
if (!n)
goto out;
@@ -787,8 +808,6 @@ struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
out:
return n;
}
-EXPORT_SYMBOL(pneigh_lookup);
-
int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,
struct net_device *dev)
@@ -2007,7 +2026,7 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh,
}
err = -ENOBUFS;
- pn = pneigh_lookup(tbl, net, dst, dev, 1);
+ pn = pneigh_create(tbl, net, dst, dev);
if (pn) {
pn->flags = ndm_flags;
pn->permanent = !!(ndm->ndm_state & NUD_PERMANENT);
@@ -3044,7 +3063,7 @@ static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
if (ndm->ndm_flags & NTF_PROXY) {
struct pneigh_entry *pn;
- pn = pneigh_lookup(tbl, net, dst, dev, 0);
+ pn = pneigh_lookup(tbl, net, dst, dev);
if (!pn) {
NL_SET_ERR_MSG(extack, "Proxy neighbour entry not found");
err = -ENOENT;
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index c0440d61cf2ff..d93b5735b0ba4 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -864,7 +864,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
(arp_fwd_proxy(in_dev, dev, rt) ||
arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
(rt->dst.dev != dev &&
- pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
+ pneigh_lookup(&arp_tbl, net, &tip, dev)))) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n)
neigh_release(n);
@@ -1089,7 +1089,7 @@ static int arp_req_set_public(struct net *net, struct arpreq *r,
if (mask) {
__be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
- if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
+ if (!pneigh_create(&arp_tbl, net, &ip, dev))
return -ENOBUFS;
return 0;
}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index fcc20c7250eb0..0412f85446958 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -563,7 +563,7 @@ int ip6_forward(struct sk_buff *skb)
/* XXX: idev->cnf.proxy_ndp? */
if (READ_ONCE(net->ipv6.devconf_all->proxy_ndp) &&
- pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
+ pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev)) {
int proxied = ip6_forward_proxy_check(skb);
if (proxied > 0) {
/* It's tempting to decrease the hop limit
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index d4c5876e17718..a3ac26c1df6d8 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1100,7 +1100,7 @@ static enum skb_drop_reason ndisc_recv_na(struct sk_buff *skb)
if (lladdr && !memcmp(lladdr, dev->dev_addr, dev->addr_len) &&
READ_ONCE(net->ipv6.devconf_all->forwarding) &&
READ_ONCE(net->ipv6.devconf_all->proxy_ndp) &&
- pneigh_lookup(&nd_tbl, net, &msg->target, dev, 0)) {
+ pneigh_lookup(&nd_tbl, net, &msg->target, dev)) {
/* XXX: idev->cnf.proxy_ndp */
goto out;
}
--
2.50.0.727.gbf7dc18ff4-goog
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