[PATCH v3 bpf/net 2/6] sockmap: Annotate sk->sk_write_space() for UDP.
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-02-19 17:38:02
Also in:
bpf
Subsystem:
bpf [l7 framework] (sockmap), networking [general], networking [sockets], the rest · Maintainers:
John Fastabend, Jakub Sitnicki, Jiayuan Chen, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Linus Torvalds
UDP TX skb->destructor() is sock_wfree(), and UDP only holds lock_sock() for UDP_CORK / MSG_MORE sendmsg(). Otherwise, sk->sk_write_space() is read locklessly. Let's use WRITE_ONCE() and READ_ONCE() for sk->sk_write_space(). Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> --- v3: Use WRITE_ONCE() in udp_bpf_update_proto() v2: Cache sk->sk_write_space in sock_wfree() --- net/core/skmsg.c | 2 +- net/core/sock.c | 8 ++++++-- net/ipv4/udp_bpf.c | 2 +- 3 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 75fa94217e1e..3d7eb2f4ac98 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c@@ -1297,7 +1297,7 @@ void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock) psock->saved_data_ready = sk->sk_data_ready; WRITE_ONCE(sk->sk_data_ready, sk_psock_verdict_data_ready); - sk->sk_write_space = sk_psock_write_space; + WRITE_ONCE(sk->sk_write_space, sk_psock_write_space); } void sk_psock_stop_verdict(struct sock *sk, struct sk_psock *psock)
diff --git a/net/core/sock.c b/net/core/sock.c
index 693e6d80f501..710f57ff3768 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c@@ -2673,8 +2673,12 @@ void sock_wfree(struct sk_buff *skb) int old; if (!sock_flag(sk, SOCK_USE_WRITE_QUEUE)) { + void (*sk_write_space)(struct sock *sk); + + sk_write_space = READ_ONCE(sk->sk_write_space); + if (sock_flag(sk, SOCK_RCU_FREE) && - sk->sk_write_space == sock_def_write_space) { + sk_write_space == sock_def_write_space) { rcu_read_lock(); free = __refcount_sub_and_test(len, &sk->sk_wmem_alloc, &old);
@@ -2690,7 +2694,7 @@ void sock_wfree(struct sk_buff *skb) * after sk_write_space() call */ WARN_ON(refcount_sub_and_test(len - 1, &sk->sk_wmem_alloc)); - sk->sk_write_space(sk); + sk_write_space(sk); len = 1; } /*
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
index 91233e37cd97..779a3a03762f 100644
--- a/net/ipv4/udp_bpf.c
+++ b/net/ipv4/udp_bpf.c@@ -158,7 +158,7 @@ int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6; if (restore) { - sk->sk_write_space = psock->saved_write_space; + WRITE_ONCE(sk->sk_write_space, psock->saved_write_space); sock_replace_proto(sk, psock->sk_proto); return 0; }
--
2.53.0.345.g96ddfc5eaa-goog