netdev - [Patch net] vsock: use new wait API for vsock_stream

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Date:   Fri, 19 May 2017 11:21:59 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Jorgen Hansen <jhansen@...are.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.vnet.ibm.com>
Subject: [Patch net] vsock: use new wait API for vsock_stream_sendmsg()

As reported by Michal, vsock_stream_sendmsg() could still
sleep at vsock_stream_has_space() after prepare_to_wait():

  vsock_stream_has_space
    vmci_transport_stream_has_space
      vmci_qpair_produce_free_space
        qp_lock
          qp_acquire_queue_mutex
            mutex_lock

Just switch to the new wait API like we did for commit
d9dc8b0f8b4e ("net: fix sleeping for sk_wait_event()").

Reported-by: Michal Kubecek <mkubecek@...e.cz>
Cc: Stefan Hajnoczi <stefanha@...hat.com>
Cc: Jorgen Hansen <jhansen@...are.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Claudio Imbrenda <imbrenda@...ux.vnet.ibm.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/vmw_vsock/af_vsock.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 6f7f675..dfc8c51e 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1540,8 +1540,7 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 	long timeout;
 	int err;
 	struct vsock_transport_send_notify_data send_data;
-
-	DEFINE_WAIT(wait);
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
 	sk = sock->sk;
 	vsk = vsock_sk(sk);
@@ -1584,11 +1583,10 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 	if (err < 0)
 		goto out;
 
-
 	while (total_written < len) {
 		ssize_t written;
 
-		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+		add_wait_queue(sk_sleep(sk), &wait);
 		while (vsock_stream_has_space(vsk) == 0 &&
 		       sk->sk_err == 0 &&
 		       !(sk->sk_shutdown & SEND_SHUTDOWN) &&
@@ -1597,33 +1595,30 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 			/* Don't wait for non-blocking sockets. */
 			if (timeout == 0) {
 				err = -EAGAIN;
-				finish_wait(sk_sleep(sk), &wait);
+				remove_wait_queue(sk_sleep(sk), &wait);
 				goto out_err;
 			}
 
 			err = transport->notify_send_pre_block(vsk, &send_data);
 			if (err < 0) {
-				finish_wait(sk_sleep(sk), &wait);
+				remove_wait_queue(sk_sleep(sk), &wait);
 				goto out_err;
 			}
 
 			release_sock(sk);
-			timeout = schedule_timeout(timeout);
+			timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout);
 			lock_sock(sk);
 			if (signal_pending(current)) {
 				err = sock_intr_errno(timeout);
-				finish_wait(sk_sleep(sk), &wait);
+				remove_wait_queue(sk_sleep(sk), &wait);
 				goto out_err;
 			} else if (timeout == 0) {
 				err = -EAGAIN;
-				finish_wait(sk_sleep(sk), &wait);
+				remove_wait_queue(sk_sleep(sk), &wait);
 				goto out_err;
 			}
-
-			prepare_to_wait(sk_sleep(sk), &wait,
-					TASK_INTERRUPTIBLE);
 		}
-		finish_wait(sk_sleep(sk), &wait);
+		remove_wait_queue(sk_sleep(sk), &wait);
 
 		/* These checks occur both as part of and after the loop
 		 * conditional since we need to check before and after
-- 
2.5.5