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amt: Store struct sock in struct amt_dev.

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amt does not need to access struct socket itself in the fast path;
it only reads struct sock, and struct socket is only used for tunnel
setup and teardown.

Let's store struct sock directly in struct amt.

amt_dev_stop() is called as dev->netdev_ops->ndo_stop().
synchronize_net() in unregister_netdevice_many_notify() ensures
that inflight amt RX fast paths finish before amt_dev is freed.

amt no longer needs synchronize_rcu() in udp_tunnel_sock_release().

Note that amt_dev_stop() looks buggy; cancel_delayed_work_sync()
should be called after udp_tunnel_sock_release().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260502031401.3557229-13-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2026-05-02 03:13:05 +00:00 committed by Jakub Kicinski
parent 173a79f696
commit 65c6e06d5a
2 changed files with 41 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
drivers/net/amt.c
View File

@ -614,24 +614,24 @@ static void amt_send_discovery(struct amt_dev *amt)
{
struct amt_header_discovery *amtd;
int hlen, tlen, offset;
struct socket *sock;
struct udphdr *udph;
struct sk_buff *skb;
struct iphdr *iph;
struct rtable *rt;
struct flowi4 fl4;
struct sock *sk;
u32 len;
int err;
rcu_read_lock();
sock = rcu_dereference(amt->sock);
if (!sock)
sk = rcu_dereference(amt->sk);
if (!sk)
goto out;
if (!netif_running(amt->stream_dev) || !netif_running(amt->dev))
goto out;
rt = ip_route_output_ports(amt->net, &fl4, sock->sk,
rt = ip_route_output_ports(amt->net, &fl4, sk,
amt->discovery_ip, amt->local_ip,
amt->gw_port, amt->relay_port,
IPPROTO_UDP, 0,
@ -690,7 +690,7 @@ static void amt_send_discovery(struct amt_dev *amt)
skb->ip_summed = CHECKSUM_NONE;
ip_select_ident(amt->net, skb, NULL);
ip_send_check(iph);
err = ip_local_out(amt->net, sock->sk, skb);
err = ip_local_out(amt->net, sk, skb);
if (unlikely(net_xmit_eval(err)))
amt->dev->stats.tx_errors++;
@ -703,24 +703,24 @@ static void amt_send_request(struct amt_dev *amt, bool v6)
{
struct amt_header_request *amtrh;
int hlen, tlen, offset;
struct socket *sock;
struct udphdr *udph;
struct sk_buff *skb;
struct iphdr *iph;
struct rtable *rt;
struct flowi4 fl4;
struct sock *sk;
u32 len;
int err;
rcu_read_lock();
sock = rcu_dereference(amt->sock);
if (!sock)
sk = rcu_dereference(amt->sk);
if (!sk)
goto out;
if (!netif_running(amt->stream_dev) || !netif_running(amt->dev))
goto out;
rt = ip_route_output_ports(amt->net, &fl4, sock->sk,
rt = ip_route_output_ports(amt->net, &fl4, sk,
amt->remote_ip, amt->local_ip,
amt->gw_port, amt->relay_port,
IPPROTO_UDP, 0,
@ -781,7 +781,7 @@ static void amt_send_request(struct amt_dev *amt, bool v6)
skb->ip_summed = CHECKSUM_NONE;
ip_select_ident(amt->net, skb, NULL);
ip_send_check(iph);
err = ip_local_out(amt->net, sock->sk, skb);
err = ip_local_out(amt->net, sk, skb);
if (unlikely(net_xmit_eval(err)))
amt->dev->stats.tx_errors++;
@ -1000,14 +1000,14 @@ static bool amt_send_membership_update(struct amt_dev *amt,
bool v6)
{
struct amt_header_membership_update *amtmu;
struct socket *sock;
struct iphdr *iph;
struct flowi4 fl4;
struct rtable *rt;
struct sock *sk;
int err;
sock = rcu_dereference_bh(amt->sock);
if (!sock)
sk = rcu_dereference_bh(amt->sk);
if (!sk)
return true;
err = skb_cow_head(skb, LL_RESERVED_SPACE(amt->dev) + sizeof(*amtmu) +
@ -1039,7 +1039,7 @@ static bool amt_send_membership_update(struct amt_dev *amt,
skb_set_inner_protocol(skb, htons(ETH_P_IP));
else
skb_set_inner_protocol(skb, htons(ETH_P_IPV6));
udp_tunnel_xmit_skb(rt, sock->sk, skb,
udp_tunnel_xmit_skb(rt, sk, skb,
fl4.saddr,
fl4.daddr,
AMT_TOS,
@ -1060,14 +1060,14 @@ static void amt_send_multicast_data(struct amt_dev *amt,
bool v6)
{
struct amt_header_mcast_data *amtmd;
struct socket *sock;
struct sk_buff *skb;
struct iphdr *iph;
struct flowi4 fl4;
struct rtable *rt;
struct sock *sk;
sock = rcu_dereference_bh(amt->sock);
if (!sock)
sk = rcu_dereference_bh(amt->sk);
if (!sk)
return;
skb = skb_copy_expand(oskb, sizeof(*amtmd) + sizeof(*iph) +
@ -1097,7 +1097,7 @@ static void amt_send_multicast_data(struct amt_dev *amt,
skb_set_inner_protocol(skb, htons(ETH_P_IP));
else
skb_set_inner_protocol(skb, htons(ETH_P_IPV6));
udp_tunnel_xmit_skb(rt, sock->sk, skb,
udp_tunnel_xmit_skb(rt, sk, skb,
fl4.saddr,
fl4.daddr,
AMT_TOS,
@ -1116,13 +1116,13 @@ static bool amt_send_membership_query(struct amt_dev *amt,
bool v6)
{
struct amt_header_membership_query *amtmq;
struct socket *sock;
struct rtable *rt;
struct flowi4 fl4;
struct sock *sk;
int err;
sock = rcu_dereference_bh(amt->sock);
if (!sock)
sk = rcu_dereference_bh(amt->sk);
if (!sk)
return true;
err = skb_cow_head(skb, LL_RESERVED_SPACE(amt->dev) + sizeof(*amtmq) +
@ -1156,7 +1156,7 @@ static bool amt_send_membership_query(struct amt_dev *amt,
skb_set_inner_protocol(skb, htons(ETH_P_IP));
else
skb_set_inner_protocol(skb, htons(ETH_P_IPV6));
udp_tunnel_xmit_skb(rt, sock->sk, skb,
udp_tunnel_xmit_skb(rt, sk, skb,
fl4.saddr,
fl4.daddr,
AMT_TOS,
@ -2554,24 +2554,24 @@ static void amt_send_advertisement(struct amt_dev *amt, __be32 nonce,
{
struct amt_header_advertisement *amta;
int hlen, tlen, offset;
struct socket *sock;
struct udphdr *udph;
struct sk_buff *skb;
struct iphdr *iph;
struct rtable *rt;
struct flowi4 fl4;
struct sock *sk;
u32 len;
int err;
rcu_read_lock();
sock = rcu_dereference(amt->sock);
if (!sock)
sk = rcu_dereference(amt->sk);
if (!sk)
goto out;
if (!netif_running(amt->stream_dev) || !netif_running(amt->dev))
goto out;
rt = ip_route_output_ports(amt->net, &fl4, sock->sk,
rt = ip_route_output_ports(amt->net, &fl4, sk,
daddr, amt->local_ip,
dport, amt->relay_port,
IPPROTO_UDP, 0,
@ -2631,7 +2631,7 @@ static void amt_send_advertisement(struct amt_dev *amt, __be32 nonce,
skb->ip_summed = CHECKSUM_NONE;
ip_select_ident(amt->net, skb, NULL);
ip_send_check(iph);
err = ip_local_out(amt->net, sock->sk, skb);
err = ip_local_out(amt->net, sk, skb);
if (unlikely(net_xmit_eval(err)))
amt->dev->stats.tx_errors++;
@ -2944,7 +2944,7 @@ static int amt_err_lookup(struct sock *sk, struct sk_buff *skb)
return 0;
}
static struct socket *amt_create_sock(struct net *net, __be16 port)
static struct sock *amt_create_sock(struct net *net, __be16 port)
{
struct udp_port_cfg udp_conf;
struct socket *sock;
@ -2960,17 +2960,17 @@ static struct socket *amt_create_sock(struct net *net, __be16 port)
if (err < 0)
return ERR_PTR(err);
return sock;
return sock->sk;
}
static int amt_socket_create(struct amt_dev *amt)
{
struct udp_tunnel_sock_cfg tunnel_cfg;
struct socket *sock;
struct sock *sk;
sock = amt_create_sock(amt->net, amt->relay_port);
if (IS_ERR(sock))
return PTR_ERR(sock);
sk = amt_create_sock(amt->net, amt->relay_port);
if (IS_ERR(sk))
return PTR_ERR(sk);
/* Mark socket as an encapsulation socket */
memset(&tunnel_cfg, 0, sizeof(tunnel_cfg));
@ -2979,9 +2979,9 @@ static int amt_socket_create(struct amt_dev *amt)
tunnel_cfg.encap_rcv = amt_rcv;
tunnel_cfg.encap_err_lookup = amt_err_lookup;
tunnel_cfg.encap_destroy = NULL;
setup_udp_tunnel_sock(amt->net, sock->sk, &tunnel_cfg);
setup_udp_tunnel_sock(amt->net, sk, &tunnel_cfg);
rcu_assign_pointer(amt->sock, sock);
rcu_assign_pointer(amt->sk, sk);
return 0;
}
@ -3019,8 +3019,8 @@ static int amt_dev_stop(struct net_device *dev)
{
struct amt_dev *amt = netdev_priv(dev);
struct amt_tunnel_list *tunnel, *tmp;
struct socket *sock;
struct sk_buff *skb;
struct sock *sk;
int i;
cancel_delayed_work_sync(&amt->req_wq);
@ -3028,11 +3028,11 @@ static int amt_dev_stop(struct net_device *dev)
cancel_delayed_work_sync(&amt->secret_wq);
/* shutdown */
sock = rtnl_dereference(amt->sock);
RCU_INIT_POINTER(amt->sock, NULL);
sk = rtnl_dereference(amt->sk);
RCU_INIT_POINTER(amt->sk, NULL);
synchronize_net();
if (sock)
udp_tunnel_sock_release(sock->sk);
if (sk)
udp_tunnel_sock_release(sk);
cancel_work_sync(&amt->event_wq);
for (i = 0; i < AMT_MAX_EVENTS; i++) {

2
include/net/amt.h
View File

@ -331,7 +331,7 @@ struct amt_dev {
enum amt_status status;
/* Generated key */
siphash_key_t key;
struct socket __rcu *sock;
struct sock __rcu *sk;
u32 max_groups;
u32 max_sources;
u32 hash_buckets;