Stefano Garzarella
2021-Feb-11 13:54 UTC
[RFC PATCH v4 09/17] virtio/vsock: dequeue callback for SOCK_SEQPACKET
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 <arseny.krasnov at kaspersky.com> >--- > 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 >
Stefano Garzarella
2021-Feb-11 14:03 UTC
[RFC PATCH v4 09/17] virtio/vsock: dequeue callback for SOCK_SEQPACKET
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 <arseny.krasnov at kaspersky.com> >>--- >>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 >>