From: Stefano Garzarella <sgarzare@redhat.com>
To: Arseny Krasnov <arseny.krasnov@kaspersky.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jorgen Hansen <jhansen@vmware.com>,
Colin Ian King <colin.king@canonical.com>,
Andra Paraschiv <andraprs@amazon.com>,
Norbert Slusarek <nslusarek@gmx.net>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"oxffffaa@gmail.com" <oxffffaa@gmail.com>
Subject: Re: [MASSMAIL KLMS] Re: [PATCH v10 04/18] af_vsock: implement SEQPACKET receive loop
Date: Mon, 7 Jun 2021 14:28:16 +0200 [thread overview]
Message-ID: <20210607122816.yas4fpfmtvlrbfku@steredhat> (raw)
In-Reply-To: <95a11b19-8266-7fc0-9426-edccd4512a2d@kaspersky.com>
On Mon, Jun 07, 2021 at 02:29:28PM +0300, Arseny Krasnov wrote:
>
>On 07.06.2021 13:48, Stefano Garzarella wrote:
>> On Fri, Jun 04, 2021 at 09:00:14PM +0300, Arseny Krasnov wrote:
>>> On 04.06.2021 18:06, Stefano Garzarella wrote:
>>>> On Thu, May 20, 2021 at 10:16:08PM +0300, Arseny Krasnov wrote:
>>>>> Add receive loop for SEQPACKET. It looks like receive loop for
>>>>> STREAM, but there are differences:
>>>>> 1) It doesn't call notify callbacks.
>>>>> 2) It doesn't care about 'SO_SNDLOWAT' and 'SO_RCVLOWAT' values, because
>>>>> there is no sense for these values in SEQPACKET case.
>>>>> 3) It waits until whole record is received or error is found during
>>>>> receiving.
>>>>> 4) It processes and sets 'MSG_TRUNC' flag.
>>>>>
>>>>> So to avoid extra conditions for two types of socket inside one loop, two
>>>>> independent functions were created.
>>>>>
>>>>> Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>>>>> ---
>>>>> v9 -> v10:
>>>>> 1) Use 'msg_data_left()' instead of direct access to 'msg_hdr'.
>>>>>
>>>>> include/net/af_vsock.h | 4 +++
>>>>> net/vmw_vsock/af_vsock.c | 72 +++++++++++++++++++++++++++++++++++++++-
>>>>> 2 files changed, 75 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>>>>> index b1c717286993..5175f5a52ce1 100644
>>>>> --- a/include/net/af_vsock.h
>>>>> +++ b/include/net/af_vsock.h
>>>>> @@ -135,6 +135,10 @@ struct vsock_transport {
>>>>> bool (*stream_is_active)(struct vsock_sock *);
>>>>> bool (*stream_allow)(u32 cid, u32 port);
>>>>>
>>>>> + /* SEQ_PACKET. */
>>>>> + ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
>>>>> + int flags, bool *msg_ready);
>>>>> +
>>>>> /* Notification. */
>>>>> int (*notify_poll_in)(struct vsock_sock *, size_t, bool *);
>>>>> int (*notify_poll_out)(struct vsock_sock *, size_t, bool *);
>>>>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>>>>> index c4f6bfa1e381..aede474343d1 100644
>>>>> --- a/net/vmw_vsock/af_vsock.c
>>>>> +++ b/net/vmw_vsock/af_vsock.c
>>>>> @@ -1974,6 +1974,73 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
>>>>> return err;
>>>>> }
>>>>>
>>>>> +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;
>>>>> + int err = 0;
>>>>> + DEFINE_WAIT(wait);
>>>>> +
>>>>> + vsk = vsock_sk(sk);
>>>>> + transport = vsk->transport;
>>>>> +
>>>>> + timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
>>>>> + msg_ready = false;
>>>>> + record_len = 0;
>>>>> +
>>>>> + while (1) {
>>>>> + ssize_t fragment_len;
>>>>> +
>>>>> + if (vsock_wait_data(sk, &wait, timeout, NULL, 0) <= 0) {
>>>>> + /* In case of any loop break(timeout, signal
>>>>> + * interrupt or shutdown), we report user that
>>>>> + * nothing was copied.
>>>>> + */
>>>>> + err = 0;
>>>> Why we report that nothing was copied?
>>>>
>>>> What happen to the bytes already copied in `msg`?
>>> Seems i need to return result of vsock_wait_data()...
>> I'm not sure.
>>
>> My biggest concern is if we reach timeout or get a signal while waiting
>> for the other pieces of a message.
>> I believe that we should not start copying a message if we have not
>> received all the fragments. Otherwise we have this problem.
>>
>> When we are sure that we have all the pieces, then we should copy them
>> without interrupting.
>>
>> IIRC this was done in previous versions.
>
>As i remember, previous versions also returned 0, because i thought,
>that for interrupted read we can copy piece of data to user's buffer,
>but we must return that nothing copied or error. In this way user
This can also be fine, but we should remove packet form the rx_queue
only when we are sure that we delivered the entire message.
>
>won't read part of message, because syscall returned that there is
>nothing to copy. So as i understand, it is not enough - user's buffer
>must be touched only when whole message is copied?
The important thing is to not remove packets from the rx_queue unless we
are sure that everything went well and we are returning the entire
message to the user.
Stefano
next prev parent reply other threads:[~2021-06-07 12:28 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 19:13 [PATCH v10 00/18] virtio/vsock: introduce SOCK_SEQPACKET support Arseny Krasnov
2021-05-20 19:14 ` [PATCH v10 01/18] af_vsock: update functions for connectible socket Arseny Krasnov
2021-05-20 19:15 ` [PATCH v10 02/18] af_vsock: separate wait data loop Arseny Krasnov
2021-05-20 19:15 ` [PATCH v10 03/18] af_vsock: separate receive " Arseny Krasnov
2021-05-20 19:16 ` [PATCH v10 04/18] af_vsock: implement SEQPACKET receive loop Arseny Krasnov
2021-05-25 14:08 ` Stefano Garzarella
2021-06-04 15:06 ` Stefano Garzarella
2021-06-04 18:00 ` [MASSMAIL KLMS] " Arseny Krasnov
2021-06-07 10:48 ` Stefano Garzarella
2021-06-07 11:29 ` Arseny Krasnov
2021-06-07 12:28 ` Stefano Garzarella [this message]
2021-05-20 19:16 ` [PATCH v10 05/18] af_vsock: implement send logic for SEQPACKET Arseny Krasnov
2021-05-20 19:16 ` [PATCH v10 06/18] af_vsock: rest of SEQPACKET support Arseny Krasnov
2021-05-25 14:17 ` Stefano Garzarella
2021-05-20 19:16 ` [PATCH v10 07/18] af_vsock: update comments for stream sockets Arseny Krasnov
2021-05-20 19:17 ` [PATCH v10 08/18] virtio/vsock: set packet's type in virtio_transport_send_pkt_info() Arseny Krasnov
2021-05-20 19:17 ` [PATCH v10 09/18] virtio/vsock: simplify credit update function API Arseny Krasnov
2021-05-20 19:17 ` [PATCH v10 10/18] virtio/vsock: defines and constants for SEQPACKET Arseny Krasnov
2021-05-20 19:17 ` [PATCH v10 11/18] virtio/vsock: dequeue callback for SOCK_SEQPACKET Arseny Krasnov
2021-06-03 14:45 ` Stefano Garzarella
2021-06-04 13:12 ` Arseny Krasnov
2021-06-04 15:03 ` Stefano Garzarella
2021-06-04 18:03 ` Arseny Krasnov
2021-06-07 11:04 ` Stefano Garzarella
2021-06-07 13:18 ` Arseny Krasnov
2021-06-08 8:23 ` Stefano Garzarella
2021-06-08 9:40 ` Arseny Krasnov
2021-06-08 10:19 ` Stefano Garzarella
2021-06-08 10:24 ` Arseny Krasnov
2021-06-08 10:39 ` Stefano Garzarella
2021-05-20 19:18 ` [PATCH v10 12/18] virtio/vsock: add SEQPACKET receive logic Arseny Krasnov
2021-06-03 14:56 ` Stefano Garzarella
2021-05-20 19:18 ` [PATCH v10 13/18] virtio/vsock: rest of SOCK_SEQPACKET support Arseny Krasnov
2021-06-03 15:14 ` Stefano Garzarella
2021-05-20 19:18 ` [PATCH v10 14/18] virtio/vsock: enable SEQPACKET for transport Arseny Krasnov
2021-06-03 15:22 ` Stefano Garzarella
2021-05-20 19:19 ` [PATCH v10 15/18] vhost/vsock: support " Arseny Krasnov
2021-06-03 15:34 ` Stefano Garzarella
2021-06-04 13:13 ` Arseny Krasnov
2021-05-20 19:19 ` [PATCH v10 16/18] vsock/loopback: enable " Arseny Krasnov
2021-05-20 19:19 ` [PATCH v10 17/18] vsock_test: add SOCK_SEQPACKET tests Arseny Krasnov
2021-06-03 15:38 ` Stefano Garzarella
2021-05-20 19:20 ` [PATCH v10 18/18] virtio/vsock: update trace event for SEQPACKET Arseny Krasnov
2021-06-03 15:40 ` Stefano Garzarella
2021-05-21 7:55 ` [PATCH v10 00/18] virtio/vsock: introduce SOCK_SEQPACKET support Stefano Garzarella
2021-05-23 12:14 ` Arseny Krasnov
2021-05-25 8:22 ` Arseny Krasnov
2021-05-25 14:52 ` Stefano Garzarella
2021-05-26 12:16 ` Arseny Krasnov
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