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[79.34.249.199]) by smtp.gmail.com with ESMTPSA id m14sm2254201edr.45.2021.04.21.01.37.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Apr 2021 01:37:34 -0700 (PDT) Date: Wed, 21 Apr 2021 10:37:32 +0200 From: Stefano Garzarella To: Arseny Krasnov Cc: Stefan Hajnoczi , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Jorgen Hansen , Andra Paraschiv , Colin Ian King , Norbert Slusarek , Alexander Popov , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stsp2@yandex.ru, oxffffaa@gmail.com Subject: Re: [RFC PATCH v8 04/19] af_vsock: implement SEQPACKET receive loop Message-ID: <20210421083732.hxlilatddifcokjx@steredhat> References: <20210413123954.3396314-1-arseny.krasnov@kaspersky.com> <20210413124250.3400313-1-arseny.krasnov@kaspersky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210413124250.3400313-1-arseny.krasnov@kaspersky.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Apr 13, 2021 at 03:42:47PM +0300, Arseny Krasnov wrote: >This adds receive loop for SEQPACKET. It looks like receive loop for >STREAM, but there is a little bit difference: >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 >--- >v7 -> v8: > - Length of message is now not returned by callback, it returns only > length of data read by each call. > - Previous case, when EAGAIN is return and dequeue loop restarted now > removed(in this simplified version we consider that message could not > be corrupted). > - MSG_TRUNC in input flags is now handled by callback. > > include/net/af_vsock.h | 4 +++ > net/vmw_vsock/af_vsock.c | 66 +++++++++++++++++++++++++++++++++++++++- > 2 files changed, 69 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..d9fb4f9a3063 100644 >--- a/net/vmw_vsock/af_vsock.c >+++ b/net/vmw_vsock/af_vsock.c >@@ -1974,6 +1974,67 @@ 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 tmp_record_len; Maybe better a name like `partial_len`, `fragment_len`, or just `read`. >+ >+ 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; >+ break; >+ } >+ >+ tmp_record_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready); I think we can avoid to pass 'flags' down to the transports. We can require that seqpacket_dequeue() should always return the real size of the packet received, and then check below if 'MSG_TRUNC' was set... >+ >+ if (tmp_record_len < 0) { >+ err = -ENOMEM; >+ break; >+ } >+ >+ record_len += tmp_record_len; >+ >+ if (msg_ready) >+ break; >+ } >+ >+ if (sk->sk_err) >+ err = -sk->sk_err; >+ else if (sk->sk_shutdown & RCV_SHUTDOWN) >+ err = 0; >+ >+ if (msg_ready && err == 0) { >+ err = record_len; >+ >+ /* Always set MSG_TRUNC if real length of packet is >+ * bigger than user's buffer. >+ */ ...here: if (flags & MSG_TRUNC && record_len > len) >+ if (record_len > len) >+ msg->msg_flags |= MSG_TRUNC; >+ } >+ >+ return err; >+} >+ > static int > vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, > int flags) >@@ -2029,7 +2090,10 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, > goto out; > } > >- err = __vsock_stream_recvmsg(sk, msg, len, flags); >+ if (sk->sk_type == SOCK_STREAM) >+ err = __vsock_stream_recvmsg(sk, msg, len, flags); >+ else >+ err = __vsock_seqpacket_recvmsg(sk, msg, len, flags); > > out: > release_sock(sk); >-- ) >2.25.1 >