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([122.192.219.205]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3695124601asm4166871a91.2.2026.05.15.20.47.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2026 20:47:59 -0700 (PDT) From: Ziyu Zhang To: Stefano Garzarella , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Andy King , George Zhang , Dmitry Torokhov , virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, r33s3n6@gmail.com, gality369@gmail.com, zhenghaoran154@gmail.com, hanguidong02@gmail.com, zzzccc427@gmail.com, Ziyu Zhang Subject: [PATCH net] vsock: keep poll shutdown state consistent Date: Sat, 16 May 2026 11:47:45 +0800 Message-ID: <20260516034745.260442-1-ziyuzhang201@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" vsock_poll() reads vsk->peer_shutdown before taking the socket lock to set EPOLLHUP and EPOLLRDHUP, then reads it again under the lock to report EOF readability. A shutdown packet can update peer_shutdown while poll is waiting for the lock, so one poll invocation can report EPOLLIN without the corresponding HUP/RDHUP bits. Keep non-connectible sockets on a single lockless READ_ONCE() snapshot. For connectible sockets, defer shutdown-derived poll bits until after lock_sock() and use one READ_ONCE() snapshot for both EOF readability and HUP/RDHUP. This preserves shutdowns that arrive before the lock is acquired and keeps all peer-shutdown-derived bits consistent for a poll pass. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Signed-off-by: Ziyu Zhang --- net/vmw_vsock/af_vsock.c | 40 ++++++++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 14 deletions(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index adcba1b7b..bed42347b 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -1122,6 +1122,25 @@ static int vsock_shutdown(struct socket *sock, int m= ode) return err; } =20 +static __poll_t vsock_poll_shutdown(struct sock *sk, u32 peer_shutdown) +{ + __poll_t mask =3D 0; + + /* INET sockets treat local write shutdown and peer write shutdown as a + * case of EPOLLHUP set. + */ + if (sk->sk_shutdown =3D=3D SHUTDOWN_MASK || + ((sk->sk_shutdown & SEND_SHUTDOWN) && + (peer_shutdown & SEND_SHUTDOWN))) + mask |=3D EPOLLHUP; + + if (sk->sk_shutdown & RCV_SHUTDOWN || + peer_shutdown & SEND_SHUTDOWN) + mask |=3D EPOLLRDHUP; + + return mask; +} + static __poll_t vsock_poll(struct file *file, struct socket *sock, poll_table *wait) { @@ -1139,19 +1158,9 @@ static __poll_t vsock_poll(struct file *file, struct= socket *sock, /* Signify that there has been an error on this socket. */ mask |=3D EPOLLERR; =20 - /* INET sockets treat local write shutdown and peer write shutdown as a - * case of EPOLLHUP set. - */ - if ((sk->sk_shutdown =3D=3D SHUTDOWN_MASK) || - ((sk->sk_shutdown & SEND_SHUTDOWN) && - (vsk->peer_shutdown & SEND_SHUTDOWN))) { - mask |=3D EPOLLHUP; - } - - if (sk->sk_shutdown & RCV_SHUTDOWN || - vsk->peer_shutdown & SEND_SHUTDOWN) { - mask |=3D EPOLLRDHUP; - } + if (!sock_type_connectible(sk->sk_type)) + mask |=3D vsock_poll_shutdown(sk, + READ_ONCE(vsk->peer_shutdown)); =20 if (sk_is_readable(sk)) mask |=3D EPOLLIN | EPOLLRDNORM; @@ -1171,6 +1180,7 @@ static __poll_t vsock_poll(struct file *file, struct = socket *sock, =20 } else if (sock_type_connectible(sk->sk_type)) { const struct vsock_transport *transport; + u32 peer_shutdown; =20 lock_sock(sk); =20 @@ -1203,10 +1213,12 @@ static __poll_t vsock_poll(struct file *file, struc= t socket *sock, * terminated should also be considered read, and we check the * shutdown flag for that. */ + peer_shutdown =3D READ_ONCE(vsk->peer_shutdown); if (sk->sk_shutdown & RCV_SHUTDOWN || - vsk->peer_shutdown & SEND_SHUTDOWN) { + peer_shutdown & SEND_SHUTDOWN) { mask |=3D EPOLLIN | EPOLLRDNORM; } + mask |=3D vsock_poll_shutdown(sk, peer_shutdown); =20 /* Connected sockets that can produce data can be written. */ if (transport && sk->sk_state =3D=3D TCP_ESTABLISHED) { --=20 2.43.0