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[79.34.249.199]) by smtp.gmail.com with ESMTPSA id i4sm4440606eje.90.2021.02.11.06.03.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Feb 2021 06:03:21 -0800 (PST) Date: Thu, 11 Feb 2021 15:03:19 +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 , Jeff Vander Stoep , 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 v4 09/17] virtio/vsock: dequeue callback for SOCK_SEQPACKET Message-ID: <20210211140319.ptqgrj5nvjn4snc7@steredhat> References: <20210207151259.803917-1-arseny.krasnov@kaspersky.com> <20210207151649.805359-1-arseny.krasnov@kaspersky.com> <20210211135428.k6cncu3m7ee4odhl@steredhat> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210211135428.k6cncu3m7ee4odhl@steredhat> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Feb 11, 2021 at 02:54:28PM +0100, Stefano Garzarella wrote: >On Sun, Feb 07, 2021 at 06:16:46PM +0300, Arseny Krasnov wrote: >>This adds transport callback and it's logic for SEQPACKET dequeue. >>Callback fetches RW packets from rx queue of socket until whole record >>is copied(if user's buffer is full, user is not woken up). This is done >>to not stall sender, because if we wake up user and it leaves syscall, >>nobody will send credit update for rest of record, and sender will wait >>for next enter of read syscall at receiver's side. So if user buffer is >>full, we just send credit update and drop data. If during copy SEQ_BEGIN >>was found(and not all data was copied), copying is restarted by reset >>user's iov iterator(previous unfinished data is dropped). >> >>Signed-off-by: Arseny Krasnov >>--- >>include/linux/virtio_vsock.h | 5 + >>include/uapi/linux/virtio_vsock.h | 16 ++++ >>net/vmw_vsock/virtio_transport_common.c | 120 ++++++++++++++++++++++++ >>3 files changed, 141 insertions(+) >> >>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h >>index dc636b727179..4d0de3dee9a4 100644 >>--- a/include/linux/virtio_vsock.h >>+++ b/include/linux/virtio_vsock.h >>@@ -36,6 +36,11 @@ struct virtio_vsock_sock { >> u32 rx_bytes; >> u32 buf_alloc; >> struct list_head rx_queue; >>+ >>+ /* For SOCK_SEQPACKET */ >>+ u32 user_read_seq_len; >>+ u32 user_read_copied; >>+ u32 curr_rx_msg_cnt; >>}; >> >>struct virtio_vsock_pkt { >>diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h >>index 1d57ed3d84d2..cf9c165e5cca 100644 >>--- a/include/uapi/linux/virtio_vsock.h >>+++ b/include/uapi/linux/virtio_vsock.h >>@@ -63,8 +63,14 @@ struct virtio_vsock_hdr { >> __le32 fwd_cnt; >>} __attribute__((packed)); >> >>+struct virtio_vsock_seq_hdr { >>+ __le32 msg_cnt; Maybe it's better 'msg_id' for this field, since we use it to identify a message. Then whether we use a counter or a random number, I think it's just an implementation detail. As Michael said, perhaps this detail should be discussed in the proposal for VIRTIO spec changes. >>+ __le32 msg_len; >>+} __attribute__((packed)); >>+ >>enum virtio_vsock_type { >> VIRTIO_VSOCK_TYPE_STREAM = 1, >>+ VIRTIO_VSOCK_TYPE_SEQPACKET = 2, >>}; >> >>enum virtio_vsock_op { >>@@ -83,6 +89,11 @@ enum virtio_vsock_op { >> VIRTIO_VSOCK_OP_CREDIT_UPDATE = 6, >> /* Request the peer to send the credit info to us */ >> VIRTIO_VSOCK_OP_CREDIT_REQUEST = 7, >>+ >>+ /* Record begin for SOCK_SEQPACKET */ >>+ VIRTIO_VSOCK_OP_SEQ_BEGIN = 8, >>+ /* Record end for SOCK_SEQPACKET */ >>+ VIRTIO_VSOCK_OP_SEQ_END = 9, >>}; >> >>/* VIRTIO_VSOCK_OP_SHUTDOWN flags values */ >>@@ -91,4 +102,9 @@ enum virtio_vsock_shutdown { >> VIRTIO_VSOCK_SHUTDOWN_SEND = 2, >>}; >> >>+/* VIRTIO_VSOCK_OP_RW flags values */ >>+enum virtio_vsock_rw { >>+ VIRTIO_VSOCK_RW_EOR = 1, >>+}; >>+ >>#endif /* _UAPI_LINUX_VIRTIO_VSOCK_H */ >>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>index 5956939eebb7..4572d01c8ea5 100644 >>--- a/net/vmw_vsock/virtio_transport_common.c >>+++ b/net/vmw_vsock/virtio_transport_common.c >>@@ -397,6 +397,126 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, >> return err; >>} >> >>+static inline void virtio_transport_remove_pkt(struct virtio_vsock_pkt *pkt) >>+{ >>+ list_del(&pkt->list); >>+ virtio_transport_free_pkt(pkt); >>+} >>+ >>+static size_t virtio_transport_drop_until_seq_begin(struct virtio_vsock_sock *vvs) >>+{ > >This function is not used here, but in the next patch, so I'd add this >with the next patch. > >>+ 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 int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk, >>+ struct msghdr *msg, >>+ bool *msg_ready) >>+{ > >Also this function is not used, maybe you can add in this patch the >virtio_transport_seqpacket_dequeue() implementation. > >>+ struct virtio_vsock_sock *vvs = vsk->trans; >>+ struct virtio_vsock_pkt *pkt; >>+ int err = 0; >>+ size_t user_buf_len = msg->msg_iter.count; >>+ >>+ *msg_ready = false; >>+ spin_lock_bh(&vvs->rx_lock); >>+ >>+ while (!*msg_ready && !list_empty(&vvs->rx_queue) && !err) { >>+ pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list); >>+ >>+ switch (le16_to_cpu(pkt->hdr.op)) { >>+ case VIRTIO_VSOCK_OP_SEQ_BEGIN: { >>+ /* Unexpected 'SEQ_BEGIN' during record copy: >>+ * Leave receive loop, 'EAGAIN' will restart it from >>+ * outer receive loop, packet is still in queue and >>+ * counters are cleared. So in next loop enter, >>+ * 'SEQ_BEGIN' will be dequeued first. User's iov >>+ * iterator will be reset in outer loop. Also >>+ * send credit update, because some bytes could be >>+ * copied. User will never see unfinished record. >>+ */ >>+ err = -EAGAIN; >>+ break; >>+ } >>+ case VIRTIO_VSOCK_OP_SEQ_END: { >>+ struct virtio_vsock_seq_hdr *seq_hdr; >>+ >>+ seq_hdr = (struct virtio_vsock_seq_hdr *)pkt->buf; >>+ /* First check that whole record is received. */ >>+ >>+ if (vvs->user_read_copied != vvs->user_read_seq_len || >>+ (le32_to_cpu(seq_hdr->msg_cnt) - vvs->curr_rx_msg_cnt) != 1) { >>+ /* Tail of current record and head of next missed, >>+ * so this EOR is from next record. Restart receive. >>+ * Current record will be dropped, next headless will >>+ * be dropped on next attempt to get record length. >>+ */ >>+ err = -EAGAIN; >>+ } else { >>+ /* Success. */ >>+ *msg_ready = true; >>+ } >>+ >>+ break; >>+ } >>+ case VIRTIO_VSOCK_OP_RW: { >>+ size_t bytes_to_copy; >>+ size_t pkt_len; >>+ >>+ pkt_len = (size_t)le32_to_cpu(pkt->hdr.len); >>+ bytes_to_copy = min(user_buf_len, pkt_len); >>+ >>+ /* sk_lock is held by caller so no one else can dequeue. >>+ * Unlock rx_lock since memcpy_to_msg() may sleep. >>+ */ >>+ spin_unlock_bh(&vvs->rx_lock); >>+ >>+ if (memcpy_to_msg(msg, pkt->buf, bytes_to_copy)) { >>+ spin_lock_bh(&vvs->rx_lock); >>+ err = -EINVAL; >>+ break; >>+ } >>+ >>+ spin_lock_bh(&vvs->rx_lock); >>+ user_buf_len -= bytes_to_copy; >>+ vvs->user_read_copied += pkt_len; >>+ >>+ if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_RW_EOR) >>+ msg->msg_flags |= MSG_EOR; >>+ break; >>+ } >>+ default: >>+ ; >>+ } >>+ >>+ /* For unexpected 'SEQ_BEGIN', keep such packet in queue, >>+ * but drop any other type of packet. >>+ */ >>+ if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_SEQ_BEGIN) { >>+ virtio_transport_dec_rx_pkt(vvs, pkt); >>+ virtio_transport_remove_pkt(pkt); >>+ } >>+ } >>+ >>+ spin_unlock_bh(&vvs->rx_lock); >>+ >>+ virtio_transport_send_credit_update(vsk, VIRTIO_VSOCK_TYPE_SEQPACKET, >>+ NULL); >>+ >>+ return err; >>+} >>+ >>ssize_t >>virtio_transport_stream_dequeue(struct vsock_sock *vsk, >> struct msghdr *msg, >>-- >>2.25.1 >>