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[79.34.249.199]) by smtp.gmail.com with ESMTPSA id u17sm4121142edr.0.2021.02.11.05.54.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Feb 2021 05:54:31 -0800 (PST) Date: Thu, 11 Feb 2021 14:54:28 +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: <20210211135428.k6cncu3m7ee4odhl@steredhat> References: <20210207151259.803917-1-arseny.krasnov@kaspersky.com> <20210207151649.805359-1-arseny.krasnov@kaspersky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210207151649.805359-1-arseny.krasnov@kaspersky.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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; >+ __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 >