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Subject[RFC PATCH v2 1/6] af_vsock/virtio/vsock: change seqpacket receive logic
Date
1) In af_vsock "loop" now is really loop: it receives
message fragments one by one, until 'msg_ready'
value is returned by transport.
2) In virtio transport, dequeue callback is called
everytime when at least one fragment of message is
received.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
include/linux/virtio_vsock.h | 3 +-
include/net/af_vsock.h | 2 +-
net/vmw_vsock/af_vsock.c | 33 +++++++++----
net/vmw_vsock/virtio_transport_common.c | 62 +++++++++++--------------
4 files changed, 52 insertions(+), 48 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 35d7eedb5e8e..e68b4029f038 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -88,7 +88,8 @@ virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
ssize_t
virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
struct msghdr *msg,
- int flags);
+ int flags,
+ bool *msg_ready);
s64 virtio_transport_stream_has_data(struct vsock_sock *vsk);
s64 virtio_transport_stream_has_space(struct vsock_sock *vsk);
u32 virtio_transport_seqpacket_has_data(struct vsock_sock *vsk);
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index ab207677e0a8..c40d341611b0 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -137,7 +137,7 @@ struct vsock_transport {

/* SEQ_PACKET. */
ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
- int flags);
+ int flags, bool *msg_ready);
int (*seqpacket_enqueue)(struct vsock_sock *vsk, struct msghdr *msg,
size_t len);
bool (*seqpacket_allow)(u32 remote_cid);
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 3e02cc3b24f8..b66884def8e8 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1881,7 +1881,7 @@ static int vsock_connectible_wait_data(struct sock *sk,
err = 0;
transport = vsk->transport;

- while ((data = vsock_connectible_has_data(vsk)) == 0) {
+ while ((data = vsock_stream_has_data(vsk)) == 0) {
prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);

if (sk->sk_err != 0 ||
@@ -2013,6 +2013,7 @@ 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;
@@ -2023,23 +2024,36 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
transport = vsk->transport;

timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+ msg_ready = false;
+ record_len = 0;

- err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
- if (err <= 0)
- goto out;
+ while (!msg_ready) {
+ ssize_t fragment_len;
+ int intr_err;

- record_len = transport->seqpacket_dequeue(vsk, msg, flags);
+ intr_err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
+ if (intr_err <= 0) {
+ err = intr_err;
+ break;
+ }

- if (record_len < 0) {
- err = -ENOMEM;
- goto out;
+ fragment_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready);
+
+ if (fragment_len < 0) {
+ err = -ENOMEM;
+ break;
+ }
+
+ record_len += fragment_len;
}

if (sk->sk_err) {
err = -sk->sk_err;
} else if (sk->sk_shutdown & RCV_SHUTDOWN) {
err = 0;
- } else {
+ }
+
+ if (msg_ready && !err) {
/* User sets MSG_TRUNC, so return real length of
* packet.
*/
@@ -2055,7 +2069,6 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
msg->msg_flags |= MSG_TRUNC;
}

-out:
return err;
}

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 169ba8b72a63..053bcea1a03f 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -407,58 +407,48 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,

static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
struct msghdr *msg,
- int flags)
+ int flags,
+ bool *msg_ready)
{
struct virtio_vsock_sock *vvs = vsk->trans;
struct virtio_vsock_pkt *pkt;
int dequeued_len = 0;
size_t user_buf_len = msg_data_left(msg);
- bool msg_ready = false;

+ *msg_ready = false;
spin_lock_bh(&vvs->rx_lock);

- if (vvs->msg_count == 0) {
- spin_unlock_bh(&vvs->rx_lock);
- return 0;
- }
+ while (!*msg_ready && !list_empty(&vvs->rx_queue) && dequeued_len >= 0) {
+ size_t pkt_len;
+ size_t bytes_to_copy;

- while (!msg_ready) {
pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);
+ pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);

- if (dequeued_len >= 0) {
- size_t pkt_len;
- size_t bytes_to_copy;
+ bytes_to_copy = min(user_buf_len, pkt_len);

- pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);
- bytes_to_copy = min(user_buf_len, pkt_len);
-
- if (bytes_to_copy) {
- int err;
-
- /* 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 (bytes_to_copy) {
+ int err;
+ /* 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);

- err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
- if (err) {
- /* Copy of message failed. Rest of
- * fragments will be freed without copy.
- */
- dequeued_len = err;
- } else {
- user_buf_len -= bytes_to_copy;
- }
+ err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);

- spin_lock_bh(&vvs->rx_lock);
- }
+ spin_lock_bh(&vvs->rx_lock);

- if (dequeued_len >= 0)
- dequeued_len += pkt_len;
+ if (err)
+ dequeued_len = err;
+ else
+ user_buf_len -= bytes_to_copy;
}

+ if (dequeued_len >= 0)
+ dequeued_len += pkt_len;
+
if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
- msg_ready = true;
+ *msg_ready = true;
vvs->msg_count--;
}

@@ -489,12 +479,12 @@ EXPORT_SYMBOL_GPL(virtio_transport_stream_dequeue);
ssize_t
virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
struct msghdr *msg,
- int flags)
+ int flags, bool *msg_ready)
{
if (flags & MSG_PEEK)
return -EOPNOTSUPP;

- return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
+ return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags, msg_ready);
}
EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);

--
2.25.1
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