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[79.18.148.79]) by smtp.gmail.com with ESMTPSA id cf10sm2158332edb.21.2021.05.13.04.37.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 May 2021 04:37:18 -0700 (PDT) Date: Thu, 13 May 2021 13:37:16 +0200 From: Stefano Garzarella To: Arseny Krasnov Cc: Stefan Hajnoczi , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Jorgen Hansen , Colin Ian King , Norbert Slusarek , Andra Paraschiv , 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 v9 04/19] af_vsock: implement SEQPACKET receive loop Message-ID: <20210513113716.admtjzo5nt2y63qi@steredhat> References: <20210508163027.3430238-1-arseny.krasnov@kaspersky.com> <20210508163317.3431119-1-arseny.krasnov@kaspersky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210508163317.3431119-1-arseny.krasnov@kaspersky.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Sat, May 08, 2021 at 07:33:14PM +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 >--- > v8 -> v9: > 1) 'tmp_record_len' renamed to 'fragment_len'. > 2) MSG_TRUNC handled in af_vsock.c instead of transport. > 3) 'flags' still passed to transport for MSG_PEEK support. Ah, right I see, sorry for the wrong suggestion to remove it. > > 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..78b9af545ca8 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; >+ break; >+ } >+ >+ fragment_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready); >+ So, IIUC, seqpacket_dequeue() must return the real length, and not the bytes copied, right? I'm not sure virtio_transport_seqpacket_do_dequeue() is doing that. I'll post a comment on that patch. >+ if (fragment_len < 0) { >+ err = -ENOMEM; >+ break; >+ } >+ >+ record_len += fragment_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) { >+ /* User sets MSG_TRUNC, so return real length of >+ * packet. >+ */ >+ if (flags & MSG_TRUNC) >+ err = record_len; >+ else >+ err = len - msg->msg_iter.count; I think is better to use msg_data_left(msg) instead of accessing fields. >+ >+ /* Always set MSG_TRUNC if real length of packet is >+ * bigger than user's buffer. >+ */ >+ 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 +2096,10 @@ 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 >