[PATCH v1 bpf/net 2/6] sockmap: Annotate sk->sk_write_space() for UDP.

[Kuniyuki Iwashima <kuniyu@google.com>]

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>
---
 net/core/skmsg.c | 2 +-
 net/core/sock.c  | 2 +-
 2 files changed, 2 insertions(+), 2 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..d828f91be4e9 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2690,7 +2690,7 @@ 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);
+		READ_ONCE(sk->sk_write_space)(sk);
 		len = 1;
 	}
 	/*
-- 
2.53.0.310.g728cabbaf7-goog