tipc: improve function tipc_wait_for_rcvmsg()
authorTung Nguyen <tung.q.nguyen@dektech.com.au>
Tue, 19 Feb 2019 04:20:48 +0000 (11:20 +0700)
committerDavid S. Miller <davem@davemloft.net>
Thu, 21 Feb 2019 21:58:05 +0000 (13:58 -0800)
This commit replaces schedule_timeout() with wait_woken()
in function tipc_wait_for_rcvmsg(). wait_woken() uses
memory barriers in its implementation to avoid potential
race condition when putting a process into sleeping state
and then waking it up.

Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/tipc/socket.c

index 81b8791..684f212 100644 (file)
@@ -1677,7 +1677,7 @@ static void tipc_sk_send_ack(struct tipc_sock *tsk)
 static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
 {
        struct sock *sk = sock->sk;
-       DEFINE_WAIT(wait);
+       DEFINE_WAIT_FUNC(wait, woken_wake_function);
        long timeo = *timeop;
        int err = sock_error(sk);
 
@@ -1685,15 +1685,17 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
                return err;
 
        for (;;) {
-               prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
                if (timeo && skb_queue_empty(&sk->sk_receive_queue)) {
                        if (sk->sk_shutdown & RCV_SHUTDOWN) {
                                err = -ENOTCONN;
                                break;
                        }
+                       add_wait_queue(sk_sleep(sk), &wait);
                        release_sock(sk);
-                       timeo = schedule_timeout(timeo);
+                       timeo = wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+                       sched_annotate_sleep();
                        lock_sock(sk);
+                       remove_wait_queue(sk_sleep(sk), &wait);
                }
                err = 0;
                if (!skb_queue_empty(&sk->sk_receive_queue))
@@ -1709,7 +1711,6 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
                if (err)
                        break;
        }
-       finish_wait(sk_sleep(sk), &wait);
        *timeop = timeo;
        return err;
 }