Commit 48766a58 authored by Tung Nguyen's avatar Tung Nguyen Committed by David S. Miller
Browse files

tipc: improve function tipc_wait_for_rcvmsg() 



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: default avatarYing Xue <ying.xue@windriver.com>
Acked-by: default avatarJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: default avatarTung Nguyen <tung.q.nguyen@dektech.com.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 223b7329

net/tipc/socket.c

+5 −4
Original line number Diff line number Diff line
@@ -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;

}

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