[PATCH v3 2/4] VSOCK: Introduce virtio-vsock.ko
Alex Bennée
alex.bennee at linaro.org
Thu Dec 10 21:23:25 UTC 2015
Stefan Hajnoczi <stefanha at redhat.com> writes:
> From: Asias He <asias at redhat.com>
>
> VM sockets virtio transport implementation. This module runs in guest
> kernel.
checkpatch warns on a bunch of whitespace/tab issues.
>
> Signed-off-by: Asias He <asias at redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha at redhat.com>
> ---
> v2:
> * Fix total_tx_buf accounting
> * Add virtio_transport global mutex to prevent races
> ---
> net/vmw_vsock/virtio_transport.c | 466 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 466 insertions(+)
> create mode 100644 net/vmw_vsock/virtio_transport.c
>
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> new file mode 100644
> index 0000000..df65dca
> --- /dev/null
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -0,0 +1,466 @@
> +/*
> + * virtio transport for vsock
> + *
> + * Copyright (C) 2013-2015 Red Hat, Inc.
> + * Author: Asias He <asias at redhat.com>
> + * Stefan Hajnoczi <stefanha at redhat.com>
> + *
> + * Some of the code is take from Gerd Hoffmann <kraxel at redhat.com>'s
> + * early virtio-vsock proof-of-concept bits.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.
> + */
> +#include <linux/spinlock.h>
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_ids.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_vsock.h>
> +#include <net/sock.h>
> +#include <linux/mutex.h>
> +#include <net/af_vsock.h>
> +
> +static struct workqueue_struct *virtio_vsock_workqueue;
> +static struct virtio_vsock *the_virtio_vsock;
> +static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
> +static void virtio_vsock_rx_fill(struct virtio_vsock *vsock);
> +
> +struct virtio_vsock {
> + /* Virtio device */
> + struct virtio_device *vdev;
> + /* Virtio virtqueue */
> + struct virtqueue *vqs[VSOCK_VQ_MAX];
> + /* Wait queue for send pkt */
> + wait_queue_head_t queue_wait;
> + /* Work item to send pkt */
> + struct work_struct tx_work;
> + /* Work item to recv pkt */
> + struct work_struct rx_work;
> + /* Mutex to protect send pkt*/
> + struct mutex tx_lock;
> + /* Mutex to protect recv pkt*/
> + struct mutex rx_lock;
Further down I got confused by what lock was what and exactly what was
being protected. If the receive and transmit paths touch separate things
it might be worth re-arranging the structure to make it clearer, eg:
/* The transmit path is protected by tx_lock */
struct mutex tx_lock;
struct work_struct tx_work;
..
..
/* The receive path is protected by rx_lock */
wait_queue_head_t queue_wait;
..
..
Which might make things a little clearer. Then all the redundant
information in the comments can be removed. I don't need to know what
is a Virtio device, virtqueue or wait_queue etc as they are implicit in
the structure name.
> + /* Number of recv buffers */
> + int rx_buf_nr;
> + /* Number of max recv buffers */
> + int rx_buf_max_nr;
> + /* Used for global tx buf limitation */
> + u32 total_tx_buf;
> + /* Guest context id, just like guest ip address */
> + u32 guest_cid;
> +};
> +
> +static struct virtio_vsock *virtio_vsock_get(void)
> +{
> + return the_virtio_vsock;
> +}
> +
> +static u32 virtio_transport_get_local_cid(void)
> +{
> + struct virtio_vsock *vsock = virtio_vsock_get();
> +
> + return vsock->guest_cid;
> +}
> +
> +static int
> +virtio_transport_send_pkt(struct vsock_sock *vsk,
> + struct virtio_vsock_pkt_info *info)
> +{
> + u32 src_cid, src_port, dst_cid, dst_port;
> + int ret, in_sg = 0, out_sg = 0;
> + struct virtio_transport *trans;
> + struct virtio_vsock_pkt *pkt;
> + struct virtio_vsock *vsock;
> + struct scatterlist hdr, buf, *sgs[2];
> + struct virtqueue *vq;
> + u32 pkt_len = info->pkt_len;
> + DEFINE_WAIT(wait);
> +
> + vsock = virtio_vsock_get();
> + if (!vsock)
> + return -ENODEV;
> +
> + src_cid = virtio_transport_get_local_cid();
> + src_port = vsk->local_addr.svm_port;
> + if (!info->remote_cid) {
> + dst_cid = vsk->remote_addr.svm_cid;
> + dst_port = vsk->remote_addr.svm_port;
> + } else {
> + dst_cid = info->remote_cid;
> + dst_port = info->remote_port;
> + }
> +
> + trans = vsk->trans;
> + vq = vsock->vqs[VSOCK_VQ_TX];
> +
> + if (pkt_len > VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE)
> + pkt_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
> + pkt_len = virtio_transport_get_credit(trans, pkt_len);
> + /* Do not send zero length OP_RW pkt*/
> + if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
> + return pkt_len;
> +
> + /* Respect global tx buf limitation */
> + mutex_lock(&vsock->tx_lock);
> + while (pkt_len + vsock->total_tx_buf > VIRTIO_VSOCK_MAX_TX_BUF_SIZE) {
> + prepare_to_wait_exclusive(&vsock->queue_wait, &wait,
> + TASK_UNINTERRUPTIBLE);
> + mutex_unlock(&vsock->tx_lock);
> + schedule();
> + mutex_lock(&vsock->tx_lock);
> + finish_wait(&vsock->queue_wait, &wait);
> + }
> + vsock->total_tx_buf += pkt_len;
> + mutex_unlock(&vsock->tx_lock);
> +
> + pkt = virtio_transport_alloc_pkt(vsk, info, pkt_len,
> + src_cid, src_port,
> + dst_cid, dst_port);
> + if (!pkt) {
> + mutex_lock(&vsock->tx_lock);
> + vsock->total_tx_buf -= pkt_len;
> + mutex_unlock(&vsock->tx_lock);
> + virtio_transport_put_credit(trans, pkt_len);
> + return -ENOMEM;
> + }
> +
> + pr_debug("%s:info->pkt_len= %d\n", __func__, info->pkt_len);
> +
> + /* Will be released in virtio_transport_send_pkt_work */
> + sock_hold(&trans->vsk->sk);
> + virtio_transport_inc_tx_pkt(pkt);
> +
> + /* Put pkt in the virtqueue */
> + sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
> + sgs[out_sg++] = &hdr;
> + if (info->msg && info->pkt_len > 0) {
> + sg_init_one(&buf, pkt->buf, pkt->len);
> + sgs[out_sg++] = &buf;
> + }
> +
> + mutex_lock(&vsock->tx_lock);
> + while ((ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, pkt,
> + GFP_KERNEL)) < 0) {
> + prepare_to_wait_exclusive(&vsock->queue_wait, &wait,
> + TASK_UNINTERRUPTIBLE);
> + mutex_unlock(&vsock->tx_lock);
> + schedule();
> + mutex_lock(&vsock->tx_lock);
> + finish_wait(&vsock->queue_wait, &wait);
> + }
> + virtqueue_kick(vq);
> + mutex_unlock(&vsock->tx_lock);
What are we protecting with tx_lock here? See comments above about
making the lock usage semantics clearer.
> +
> + return pkt_len;
> +}
> +
> +static struct virtio_transport_pkt_ops virtio_ops = {
> + .send_pkt = virtio_transport_send_pkt,
> +};
> +
> +static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
> +{
> + int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
> + struct virtio_vsock_pkt *pkt;
> + struct scatterlist hdr, buf, *sgs[2];
> + struct virtqueue *vq;
> + int ret;
> +
> + vq = vsock->vqs[VSOCK_VQ_RX];
> +
> + do {
> + pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> + if (!pkt) {
> + pr_debug("%s: fail to allocate pkt\n", __func__);
> + goto out;
> + }
> +
> + /* TODO: use mergeable rx buffer */
TODO's should end up in merged code.
> + pkt->buf = kmalloc(buf_len, GFP_KERNEL);
> + if (!pkt->buf) {
> + pr_debug("%s: fail to allocate pkt->buf\n", __func__);
> + goto err;
> + }
> +
> + sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
> + sgs[0] = &hdr;
> +
> + sg_init_one(&buf, pkt->buf, buf_len);
> + sgs[1] = &buf;
> + ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
> + if (ret)
> + goto err;
> + vsock->rx_buf_nr++;
> + } while (vq->num_free);
> + if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
> + vsock->rx_buf_max_nr = vsock->rx_buf_nr;
> +out:
> + virtqueue_kick(vq);
> + return;
> +err:
> + virtqueue_kick(vq);
> + virtio_transport_free_pkt(pkt);
You could free the pkt memory at the fail site and just have one exit path.
> + return;
> +}
> +
> +static void virtio_transport_send_pkt_work(struct work_struct *work)
> +{
> + struct virtio_vsock *vsock =
> + container_of(work, struct virtio_vsock, tx_work);
> + struct virtio_vsock_pkt *pkt;
> + bool added = false;
> + struct virtqueue *vq;
> + unsigned int len;
> + struct sock *sk;
> +
> + vq = vsock->vqs[VSOCK_VQ_TX];
> + mutex_lock(&vsock->tx_lock);
> + do {
You can move the declarations of pkt/len into the do block.
> + virtqueue_disable_cb(vq);
> + while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
And the sk declaration here
> + sk = &pkt->trans->vsk->sk;
> + virtio_transport_dec_tx_pkt(pkt);
> + /* Release refcnt taken in virtio_transport_send_pkt */
> + sock_put(sk);
> + vsock->total_tx_buf -= pkt->len;
> + virtio_transport_free_pkt(pkt);
> + added = true;
> + }
> + } while (!virtqueue_enable_cb(vq));
> + mutex_unlock(&vsock->tx_lock);
> +
> + if (added)
> + wake_up(&vsock->queue_wait);
> +}
> +
> +static void virtio_transport_recv_pkt_work(struct work_struct *work)
> +{
> + struct virtio_vsock *vsock =
> + container_of(work, struct virtio_vsock, rx_work);
> + struct virtio_vsock_pkt *pkt;
> + struct virtqueue *vq;
> + unsigned int len;
Same as above for pkt, len.
> +
> + vq = vsock->vqs[VSOCK_VQ_RX];
> + mutex_lock(&vsock->rx_lock);
> + do {
> + virtqueue_disable_cb(vq);
> + while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
> + pkt->len = len;
> + virtio_transport_recv_pkt(pkt);
> + vsock->rx_buf_nr--;
> + }
> + } while (!virtqueue_enable_cb(vq));
> +
> + if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
> + virtio_vsock_rx_fill(vsock);
> + mutex_unlock(&vsock->rx_lock);
> +}
> +
> +static void virtio_vsock_ctrl_done(struct virtqueue *vq)
> +{
> +}
> +
> +static void virtio_vsock_tx_done(struct virtqueue *vq)
> +{
> + struct virtio_vsock *vsock = vq->vdev->priv;
> +
> + if (!vsock)
> + return;
> + queue_work(virtio_vsock_workqueue, &vsock->tx_work);
> +}
> +
> +static void virtio_vsock_rx_done(struct virtqueue *vq)
> +{
> + struct virtio_vsock *vsock = vq->vdev->priv;
> +
> + if (!vsock)
> + return;
> + queue_work(virtio_vsock_workqueue, &vsock->rx_work);
> +}
> +
> +static int
> +virtio_transport_socket_init(struct vsock_sock *vsk, struct vsock_sock *psk)
> +{
> + struct virtio_transport *trans;
> + int ret;
> +
> + ret = virtio_transport_do_socket_init(vsk, psk);
> + if (ret)
> + return ret;
> +
> + trans = vsk->trans;
> + trans->ops = &virtio_ops;
> + return ret;
> +}
> +
> +static struct vsock_transport virtio_transport = {
> + .get_local_cid = virtio_transport_get_local_cid,
> +
> + .init = virtio_transport_socket_init,
> + .destruct = virtio_transport_destruct,
> + .release = virtio_transport_release,
> + .connect = virtio_transport_connect,
> + .shutdown = virtio_transport_shutdown,
> +
> + .dgram_bind = virtio_transport_dgram_bind,
> + .dgram_dequeue = virtio_transport_dgram_dequeue,
> + .dgram_enqueue = virtio_transport_dgram_enqueue,
> + .dgram_allow = virtio_transport_dgram_allow,
> +
> + .stream_dequeue = virtio_transport_stream_dequeue,
> + .stream_enqueue = virtio_transport_stream_enqueue,
> + .stream_has_data = virtio_transport_stream_has_data,
> + .stream_has_space = virtio_transport_stream_has_space,
> + .stream_rcvhiwat = virtio_transport_stream_rcvhiwat,
> + .stream_is_active = virtio_transport_stream_is_active,
> + .stream_allow = virtio_transport_stream_allow,
> +
> + .notify_poll_in = virtio_transport_notify_poll_in,
> + .notify_poll_out = virtio_transport_notify_poll_out,
> + .notify_recv_init = virtio_transport_notify_recv_init,
> + .notify_recv_pre_block = virtio_transport_notify_recv_pre_block,
> + .notify_recv_pre_dequeue = virtio_transport_notify_recv_pre_dequeue,
> + .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
> + .notify_send_init = virtio_transport_notify_send_init,
> + .notify_send_pre_block = virtio_transport_notify_send_pre_block,
> + .notify_send_pre_enqueue = virtio_transport_notify_send_pre_enqueue,
> + .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
> +
> + .set_buffer_size = virtio_transport_set_buffer_size,
> + .set_min_buffer_size = virtio_transport_set_min_buffer_size,
> + .set_max_buffer_size = virtio_transport_set_max_buffer_size,
> + .get_buffer_size = virtio_transport_get_buffer_size,
> + .get_min_buffer_size = virtio_transport_get_min_buffer_size,
> + .get_max_buffer_size = virtio_transport_get_max_buffer_size,
> +};
> +
> +static int virtio_vsock_probe(struct virtio_device *vdev)
> +{
> + vq_callback_t *callbacks[] = {
> + virtio_vsock_ctrl_done,
> + virtio_vsock_rx_done,
> + virtio_vsock_tx_done,
> + };
> + const char *names[] = {
> + "ctrl",
> + "rx",
> + "tx",
> + };
> + struct virtio_vsock *vsock = NULL;
> + u32 guest_cid;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
> + if (ret)
> + return ret;
> +
> + /* Only one virtio-vsock device per guest is supported */
> + if (the_virtio_vsock) {
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
> + if (!vsock) {
> + ret = -ENOMEM;
> + goto out;
Won't this attempt to kfree a NULL vsock?
> + }
> +
> + vsock->vdev = vdev;
> +
> + ret = vsock->vdev->config->find_vqs(vsock->vdev, VSOCK_VQ_MAX,
> + vsock->vqs, callbacks, names);
> + if (ret < 0)
> + goto out;
> +
> + vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
> + &guest_cid, sizeof(guest_cid));
> + vsock->guest_cid = le32_to_cpu(guest_cid);
> + pr_debug("%s:guest_cid=%d\n", __func__, vsock->guest_cid);
> +
> + ret = vsock_core_init(&virtio_transport);
> + if (ret < 0)
> + goto out_vqs;
> +
> + vsock->rx_buf_nr = 0;
> + vsock->rx_buf_max_nr = 0;
> +
> + vdev->priv = the_virtio_vsock = vsock;
> + init_waitqueue_head(&vsock->queue_wait);
> + mutex_init(&vsock->tx_lock);
> + mutex_init(&vsock->rx_lock);
> + INIT_WORK(&vsock->rx_work, virtio_transport_recv_pkt_work);
> + INIT_WORK(&vsock->tx_work, virtio_transport_send_pkt_work);
> +
> + mutex_lock(&vsock->rx_lock);
> + virtio_vsock_rx_fill(vsock);
> + mutex_unlock(&vsock->rx_lock);
> +
> + mutex_unlock(&the_virtio_vsock_mutex);
> + return 0;
> +
> +out_vqs:
> + vsock->vdev->config->del_vqs(vsock->vdev);
> +out:
> + kfree(vsock);
> + mutex_unlock(&the_virtio_vsock_mutex);
> + return ret;
> +}
> +
> +static void virtio_vsock_remove(struct virtio_device *vdev)
> +{
> + struct virtio_vsock *vsock = vdev->priv;
> +
> + mutex_lock(&the_virtio_vsock_mutex);
> + the_virtio_vsock = NULL;
> + vsock_core_exit();
> + mutex_unlock(&the_virtio_vsock_mutex);
> +
> + kfree(vsock);
> +}
> +
> +static struct virtio_device_id id_table[] = {
> + { VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static unsigned int features[] = {
> +};
> +
> +static struct virtio_driver virtio_vsock_driver = {
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .id_table = id_table,
> + .probe = virtio_vsock_probe,
> + .remove = virtio_vsock_remove,
> +};
> +
> +static int __init virtio_vsock_init(void)
> +{
> + int ret;
> +
> + virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
> + if (!virtio_vsock_workqueue)
> + return -ENOMEM;
> + ret = register_virtio_driver(&virtio_vsock_driver);
> + if (ret)
> + destroy_workqueue(virtio_vsock_workqueue);
> + return ret;
> +}
> +
> +static void __exit virtio_vsock_exit(void)
> +{
> + unregister_virtio_driver(&virtio_vsock_driver);
> + destroy_workqueue(virtio_vsock_workqueue);
> +}
> +
> +module_init(virtio_vsock_init);
> +module_exit(virtio_vsock_exit);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Asias He");
> +MODULE_DESCRIPTION("virtio transport for vsock");
> +MODULE_DEVICE_TABLE(virtio, id_table);
--
Alex Bennée
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