From 33930840b5f0a79f826e7c69dc6cd78f72a67481 Mon Sep 17 00:00:00 2001 From: Runyu Xiao Date: Thu, 11 Jun 2026 13:35:56 +0800 Subject: [PATCH] sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE xprtsock replaces and restores sk->sk_data_ready and sk->sk_write_space on live sockets with plain stores, and xs_udp_do_set_buffer_size() invokes sk->sk_write_space via a plain load. These callback pointers are shared with generic socket and protocol paths that may read or invoke them concurrently, so xprtsock needs the same READ_ONCE()/WRITE_ONCE() callback visibility contract that the validated 4022 family applied elsewhere. When SUNRPC takes over an AF_LOCAL, UDP, or TCP socket and later restores the lower-socket callbacks during teardown, another CPU may still hold an earlier callback snapshot. The plain replace/restore pattern leaves the same visibility hole as the validated 4022 family, so a stale snapshot can still invoke xs_data_ready() or xs_udp_write_space() after the live callback fields have already been restored to the lower-socket handlers. Use WRITE_ONCE() for the shared sk_data_ready and sk_write_space stores in xs_local_finish_connecting(), xs_udp_finish_connecting(), xs_tcp_finish_connecting(), and xs_restore_old_callbacks(). Use READ_ONCE() for the direct sk_write_space invocation in xs_udp_do_set_buffer_size(). This matches the required callback visibility contract while leaving adjacent sk_state_change and sk_error_report handling unchanged. Fixes: a246b0105bbd ("[PATCH] RPC: introduce client-side transport switch") Signed-off-by: Runyu Xiao Signed-off-by: Trond Myklebust --- net/sunrpc/xprtsock.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 359407aae03e..d735e6ec7e37 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1202,9 +1202,9 @@ static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk) static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk) { - sk->sk_data_ready = transport->old_data_ready; + WRITE_ONCE(sk->sk_data_ready, transport->old_data_ready); sk->sk_state_change = transport->old_state_change; - sk->sk_write_space = transport->old_write_space; + WRITE_ONCE(sk->sk_write_space, transport->old_write_space); sk->sk_error_report = transport->old_error_report; } @@ -1664,6 +1664,7 @@ static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt) { struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); struct sock *sk = transport->inet; + void (*write_space)(struct sock *sock); if (transport->rcvsize) { sk->sk_userlocks |= SOCK_RCVBUF_LOCK; @@ -1672,7 +1673,8 @@ static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt) if (transport->sndsize) { sk->sk_userlocks |= SOCK_SNDBUF_LOCK; sk->sk_sndbuf = transport->sndsize * xprt->max_reqs * 2; - sk->sk_write_space(sk); + write_space = READ_ONCE(sk->sk_write_space); + write_space(sk); } } @@ -1988,8 +1990,8 @@ static int xs_local_finish_connecting(struct rpc_xprt *xprt, xs_save_old_callbacks(transport, sk); sk->sk_user_data = xprt; - sk->sk_data_ready = xs_data_ready; - sk->sk_write_space = xs_udp_write_space; + WRITE_ONCE(sk->sk_data_ready, xs_data_ready); + WRITE_ONCE(sk->sk_write_space, xs_udp_write_space); sk->sk_state_change = xs_local_state_change; sk->sk_error_report = xs_error_report; sk->sk_use_task_frag = false; @@ -2191,8 +2193,8 @@ static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock) xs_save_old_callbacks(transport, sk); sk->sk_user_data = xprt; - sk->sk_data_ready = xs_data_ready; - sk->sk_write_space = xs_udp_write_space; + WRITE_ONCE(sk->sk_data_ready, xs_data_ready); + WRITE_ONCE(sk->sk_write_space, xs_udp_write_space); sk->sk_use_task_frag = false; xprt_set_connected(xprt); @@ -2378,9 +2380,9 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock) xs_save_old_callbacks(transport, sk); sk->sk_user_data = xprt; - sk->sk_data_ready = xs_data_ready; + WRITE_ONCE(sk->sk_data_ready, xs_data_ready); sk->sk_state_change = xs_tcp_state_change; - sk->sk_write_space = xs_tcp_write_space; + WRITE_ONCE(sk->sk_write_space, xs_tcp_write_space); sk->sk_error_report = xs_error_report; sk->sk_use_task_frag = false;