Re: [RFC PATCH v5 02/19] af_vsock: separate wait data loop
From: Arseny Krasnov
Date: Thu Feb 25 2021 - 12:05:30 EST
On 25.02.2021 17:24, Jorgen Hansen wrote:
>
> On 18 Feb 2021, at 06:36, Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx> wrote:
>
>
>
> This moves wait loop for data to dedicated function, because later
>
> it will be used by SEQPACKET data receive loop.
>
>
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
>
> ---
>
> net/vmw_vsock/af_vsock.c | 155 +++++++++++++++++++++------------------
>
> 1 file changed, 83 insertions(+), 72 deletions(-)
>
>
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>
> index 656370e11707..6cf7bb977aa1 100644
>
> --- a/net/vmw_vsock/af_vsock.c
>
> +++ b/net/vmw_vsock/af_vsock.c
>
> @@ -1832,6 +1832,68 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
>
> return err;
>
> }
>
>
>
> +static int vsock_wait_data(struct sock *sk, struct wait_queue_entry *wait,
>
> + long timeout,
>
> + struct vsock_transport_recv_notify_data *recv_data,
>
> + size_t target)
>
> +{
>
> + const struct vsock_transport *transport;
>
> + struct vsock_sock *vsk;
>
> + s64 data;
>
> + int err;
>
> +
>
> + vsk = vsock_sk(sk);
>
> + err = 0;
>
> + transport = vsk->transport;
>
> + prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
>
> +
>
> + while ((data = vsock_stream_has_data(vsk)) == 0) {
>
In the original code, the prepare_to_wait() is called for each iteration of the while loop. In this
>
version, it is only called once. So if we do multiple iterations, the thread would be in the
>
TASK_RUNNING state, and subsequent schedule_timeout() will return immediately. So
>
looks like the prepare_to_wait() should be move here, in case we have a spurious wake_up.
Thank you, i'll fix it
>
>
> + if (sk->sk_err != 0 ||
>
> + (sk->sk_shutdown & RCV_SHUTDOWN) ||
>
> + (vsk->peer_shutdown & SEND_SHUTDOWN)) {
>
> + break;
>
> + }
>
> +
>
> + /* Don't wait for non-blocking sockets. */
>
> + if (timeout == 0) {
>
> + err = -EAGAIN;
>
> + break;
>
> + }
>
> +
>
> + if (recv_data) {
>
> + err = transport->notify_recv_pre_block(vsk, target, recv_data);
>
> + if (err < 0)
>
> + break;
>
> + }
>
> +
>
> + release_sock(sk);
>
> + timeout = schedule_timeout(timeout);
>
> + lock_sock(sk);
>
> +
>
> + if (signal_pending(current)) {
>
> + err = sock_intr_errno(timeout);
>
> + break;
>
> + } else if (timeout == 0) {
>
> + err = -EAGAIN;
>
> + break;
>
> + }
>
> + }
>
> +
>
> + finish_wait(sk_sleep(sk), wait);
>
> +
>
> + if (err)
>
> + return err;
>
> +
>
> + /* Internal transport error when checking for available
>
> + * data. XXX This should be changed to a connection
>
> + * reset in a later change.
>
> + */
>
> + if (data < 0)
>
> + return -ENOMEM;
>
> +
>
> + return data;
>
> +}
>
> +
>
> static int
>
> vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>
> int flags)
>
> @@ -1911,85 +1973,34 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>
>
>
>
>
> while (1) {
>
> - s64 ready;
>
> -
>
> - prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
>
> - ready = vsock_stream_has_data(vsk);
>
> -
>
> - if (ready == 0) {
>
> - if (sk->sk_err != 0 ||
>
> - (sk->sk_shutdown & RCV_SHUTDOWN) ||
>
> - (vsk->peer_shutdown & SEND_SHUTDOWN)) {
>
> - finish_wait(sk_sleep(sk), &wait);
>
> - break;
>
> - }
>
> - /* Don't wait for non-blocking sockets. */
>
> - if (timeout == 0) {
>
> - err = -EAGAIN;
>
> - finish_wait(sk_sleep(sk), &wait);
>
> - break;
>
> - }
>
> + ssize_t read;
>
>
>
> - err = transport->notify_recv_pre_block(
>
> - vsk, target, &recv_data);
>
> - if (err < 0) {
>
> - finish_wait(sk_sleep(sk), &wait);
>
> - break;
>
> - }
>
> - release_sock(sk);
>
> - timeout = schedule_timeout(timeout);
>
> - lock_sock(sk);
>
> + err = vsock_wait_data(sk, &wait, timeout, &recv_data, target);
>
> + if (err <= 0)
>
> + break;
>
>
>
> - if (signal_pending(current)) {
>
> - err = sock_intr_errno(timeout);
>
> - finish_wait(sk_sleep(sk), &wait);
>
> - break;
>
> - } else if (timeout == 0) {
>
> - err = -EAGAIN;
>
> - finish_wait(sk_sleep(sk), &wait);
>
> - break;
>
> - }
>
> - } else {
>
> - ssize_t read;
>
> -
>
> - finish_wait(sk_sleep(sk), &wait);
>
> -
>
> - if (ready < 0) {
>
> - /* Invalid queue pair content. XXX This should
>
> - * be changed to a connection reset in a later
>
> - * change.
>
> - */
>
> -
>
> - err = -ENOMEM;
>
> - goto out;
>
> - }
>
> -
>
> - err = transport->notify_recv_pre_dequeue(
>
> - vsk, target, &recv_data);
>
> - if (err < 0)
>
> - break;
>
> + err = transport->notify_recv_pre_dequeue(vsk, target,
>
> + &recv_data);
>
> + if (err < 0)
>
> + break;
>
>
>
> - read = transport->stream_dequeue(
>
> - vsk, msg,
>
> - len - copied, flags);
>
> - if (read < 0) {
>
> - err = -ENOMEM;
>
> - break;
>
> - }
>
> + read = transport->stream_dequeue(vsk, msg, len - copied, flags);
>
> + if (read < 0) {
>
> + err = -ENOMEM;
>
> + break;
>
> + }
>
>
>
> - copied += read;
>
> + copied += read;
>
>
>
> - err = transport->notify_recv_post_dequeue(
>
> - vsk, target, read,
>
> - !(flags & MSG_PEEK), &recv_data);
>
> - if (err < 0)
>
> - goto out;
>
> + err = transport->notify_recv_post_dequeue(vsk, target, read,
>
> + !(flags & MSG_PEEK), &recv_data);
>
> + if (err < 0)
>
> + goto out;
>
>
>
> - if (read >= target || flags & MSG_PEEK)
>
> - break;
>
> + if (read >= target || flags & MSG_PEEK)
>
> + break;
>
>
>
> - target -= read;
>
> - }
>
> + target -= read;
>
> }
>
>
>
> if (sk->sk_err)
>
> --
>
> 2.25.1
>
>
>