netdev - Re: [RFC PATCH v1 08/16] af_vsock: change SEQPACKET receive loop

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Date:   Wed, 30 Jun 2021 20:47:56 +0300
From:   Arseny Krasnov <arseny.krasnov@...persky.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
CC:     Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jorgen Hansen <jhansen@...are.com>,
        Andra Paraschiv <andraprs@...zon.com>,
        Colin Ian King <colin.king@...onical.com>,
        Norbert Slusarek <nslusarek@....net>,
        kvm <kvm@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        netdev <netdev@...r.kernel.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Krasnov Arseniy <oxffffaa@...il.com>
Subject: Re: [RFC PATCH v1 08/16] af_vsock: change SEQPACKET receive loop


On 30.06.2021 15:12, Stefano Garzarella wrote:
> On Mon, Jun 28, 2021 at 01:03:28PM +0300, Arseny Krasnov wrote:
>> Receive "loop" now really loop: it reads fragments one by
>> one, sleeping if queue is empty.
>>
>> NOTE: 'msg_ready' pointer is not passed to 'seqpacket_dequeue()'
>> here - it change callback interface, so it is moved to next patch.
>>
>> Signed-off-by: Arseny Krasnov <arseny.krasnov@...persky.com>
>> ---
>> net/vmw_vsock/af_vsock.c | 31 ++++++++++++++++++++++---------
>> 1 file changed, 22 insertions(+), 9 deletions(-)
> I think you can merge patches 8, 9, and 10 together since we
> are touching the seqpacket_dequeue() behaviour.
>
> Then you can remove in separate patches the unneeded parts (e.g.
> seqpacket_has_data, msg_count, etc.).
>
> Thanks,
> Stefano
Ack
>
>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>> index 59ce35da2e5b..9552f05119f2 100644
>> --- a/net/vmw_vsock/af_vsock.c
>> +++ b/net/vmw_vsock/af_vsock.c
>> @@ -2003,6 +2003,7 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
>>                                    size_t len, int flags)
>> {
>>       const struct vsock_transport *transport;
>> +      bool msg_ready;
>>       struct vsock_sock *vsk;
>>       ssize_t record_len;
>>       long timeout;
>> @@ -2013,23 +2014,36 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
>>       transport = vsk->transport;
>>
>>       timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
>> +      msg_ready = false;
>> +      record_len = 0;
>>
>> -      err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
>> -      if (err <= 0)
>> -              goto out;
>> +      while (!msg_ready) {
>> +              ssize_t fragment_len;
>> +              int intr_err;
>>
>> -      record_len = transport->seqpacket_dequeue(vsk, msg, flags);
>> +              intr_err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
>> +              if (intr_err <= 0) {
>> +                      err = intr_err;
>> +                      break;
>> +              }
>>
>> -      if (record_len < 0) {
>> -              err = -ENOMEM;
>> -              goto out;
>> +              fragment_len = transport->seqpacket_dequeue(vsk, msg, flags);
>> +
>> +              if (fragment_len < 0) {
>> +                      err = -ENOMEM;
>> +                      break;
>> +              }
>> +
>> +              record_len += fragment_len;
>>       }
>>
>>       if (sk->sk_err) {
>>               err = -sk->sk_err;
>>       } else if (sk->sk_shutdown & RCV_SHUTDOWN) {
>>               err = 0;
>> -      } else {
>> +      }
>> +
>> +      if (msg_ready && !err) {
>>               /* User sets MSG_TRUNC, so return real length of
>>                * packet.
>>                */
>> @@ -2045,7 +2059,6 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
>>                       msg->msg_flags |= MSG_TRUNC;
>>       }
>>
>> -out:
>>       return err;
>> }
>>
>> --
>> 2.25.1
>>
>