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[79.34.249.199]) by smtp.gmail.com with ESMTPSA id i3sm6673746wra.66.2021.03.25.03.08.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Mar 2021 03:08:13 -0700 (PDT) Date: Thu, 25 Mar 2021 11:08:10 +0100 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 v7 12/22] virtio/vsock: fetch length for SEQPACKET record Message-ID: <20210325100810.ygmg6vqb2f7rxoyx@steredhat> References: <20210323130716.2459195-1-arseny.krasnov@kaspersky.com> <20210323131258.2461163-1-arseny.krasnov@kaspersky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210323131258.2461163-1-arseny.krasnov@kaspersky.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 23, 2021 at 04:12:55PM +0300, Arseny Krasnov wrote: >This adds transport callback which tries to fetch record begin marker >from socket's rx queue. It is called from af_vsock.c before reading data >packets of record. > >Signed-off-by: Arseny Krasnov >--- > v6 -> v7: > 1) Now 'virtio_transport_seqpacket_seq_get_len()' returns 0, if rx > queue of socket is empty. Else it returns length of current message > to handle. > 2) If dequeue callback is called, but there is no detected length of > message to dequeue, EAGAIN is returned, and outer loop restarts > receiving. > > net/vmw_vsock/virtio_transport_common.c | 61 +++++++++++++++++++++++++ > 1 file changed, 61 insertions(+) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index a8f4326e45e8..41f05034593e 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -399,6 +399,62 @@ static inline void virtio_transport_remove_pkt(struct virtio_vsock_pkt *pkt) > virtio_transport_free_pkt(pkt); > } > >+static size_t virtio_transport_drop_until_seq_begin(struct >virtio_vsock_sock *vvs) >+{ >+ struct virtio_vsock_pkt *pkt, *n; >+ size_t bytes_dropped = 0; >+ >+ list_for_each_entry_safe(pkt, n, &vvs->rx_queue, list) { >+ if (le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_SEQ_BEGIN) >+ break; >+ >+ bytes_dropped += le32_to_cpu(pkt->hdr.len); >+ virtio_transport_dec_rx_pkt(vvs, pkt); >+ virtio_transport_remove_pkt(pkt); >+ } >+ >+ return bytes_dropped; >+} >+ >+static size_t virtio_transport_seqpacket_seq_get_len(struct vsock_sock *vsk) >+{ >+ struct virtio_vsock_seq_hdr *seq_hdr; >+ struct virtio_vsock_sock *vvs; >+ struct virtio_vsock_pkt *pkt; >+ size_t bytes_dropped = 0; >+ >+ vvs = vsk->trans; >+ >+ spin_lock_bh(&vvs->rx_lock); >+ >+ /* Have some record to process, return it's length. */ >+ if (vvs->seq_state.user_read_seq_len) >+ goto out; >+ >+ /* Fetch all orphaned 'RW' packets and send credit update. */ >+ bytes_dropped = virtio_transport_drop_until_seq_begin(vvs); >+ >+ if (list_empty(&vvs->rx_queue)) >+ goto out; >+ >+ pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list); >+ >+ vvs->seq_state.user_read_copied = 0; >+ >+ seq_hdr = (struct virtio_vsock_seq_hdr *)pkt->buf; >+ vvs->seq_state.user_read_seq_len = le32_to_cpu(seq_hdr->msg_len); >+ vvs->seq_state.curr_rx_msg_id = le32_to_cpu(seq_hdr->msg_id); >+ virtio_transport_dec_rx_pkt(vvs, pkt); >+ virtio_transport_remove_pkt(pkt); >+out: >+ spin_unlock_bh(&vvs->rx_lock); >+ >+ if (bytes_dropped) >+ virtio_transport_send_credit_update(vsk); >+ >+ return vvs->seq_state.user_read_seq_len; >+} >+ > static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, > bool *msg_ready) >@@ -522,6 +578,11 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk, > if (flags & MSG_PEEK) > return -EOPNOTSUPP; > >+ *msg_len = virtio_transport_seqpacket_seq_get_len(vsk); >+ >+ if (*msg_len == 0) >+ return -EAGAIN; >+ Okay, I see now, I think you can move this patch before the previous one or merge them in a single patch, it is better to review and to bisect. As mentioned, I think we can return msg_len if virtio_transport_seqpacket_do_dequeue() does not fail, otherwise the error. I mean something like this: static ssize_t virtio_transport_seqpacket_do_dequeue(...) { size_t msg_len; ssize_t ret; msg_len = virtio_transport_seqpacket_seq_get_len(vsk); if (msg_len == 0) return -EAGAIN; ret = virtio_transport_seqpacket_do_dequeue(vsk, msg, msg_ready); if (ret < 0) return ret; return msg_len; } > return virtio_transport_seqpacket_do_dequeue(vsk, msg, msg_ready); > } > EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue); >-- 2.25.1 >