Re: [RFC PATCH 3/5] vsock/virtio: can_msgzerocopy adapts to multi-devices

[Stefano Garzarella]

On Fri, May 17, 2024 at 10:46:05PM GMT, Xuewei Niu wrote:
Adds a new argument, named "cid", to let them know which `virtio_vsock` to
be selected.
Signed-off-by: Xuewei Niu <niuxuewei....@antgroup.com>
---
include/linux/virtio_vsock.h            | 2 +-
net/vmw_vsock/virtio_transport.c        | 5 ++---
net/vmw_vsock/virtio_transport_common.c | 6 +++---
3 files changed, 6 insertions(+), 7 deletions(-)

Every commit in linux must be working to support bisection. So these 
changes should be made before adding multi-device support.


diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index c82089dee0c8..21bfd5e0c2e7 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -168,7 +168,7 @@ struct virtio_transport {
         * extra checks and can perform zerocopy transmission by
         * default.
         */
-       bool (*can_msgzerocopy)(int bufs_num);
+       bool (*can_msgzerocopy)(u32 cid, int bufs_num);
};

ssize_t
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 93d25aeafb83..998b22e5ce36 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -521,14 +521,13 @@ static void virtio_vsock_rx_done(struct virtqueue *vq)
        queue_work(virtio_vsock_workqueue, &vsock->rx_work);
}

-static bool virtio_transport_can_msgzerocopy(int bufs_num)
+static bool virtio_transport_can_msgzerocopy(u32 cid, int bufs_num)
{
        struct virtio_vsock *vsock;
        bool res = false;

        rcu_read_lock();
-
-       vsock = rcu_dereference(the_virtio_vsock);
+       vsock = virtio_transport_get_virtio_vsock(cid);
        if (vsock) {
                struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];

diff --git a/net/vmw_vsock/virtio_transport_common.c 
b/net/vmw_vsock/virtio_transport_common.c
index bed75a41419e..e7315d7b9af1 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -39,7 +39,7 @@ virtio_transport_get_ops(struct vsock_sock *vsk)

static bool virtio_transport_can_zcopy(const struct virtio_transport *t_ops,
                                       struct virtio_vsock_pkt_info *info,
-                                      size_t pkt_len)
+                                      size_t pkt_len, unsigned int cid)
{
        struct iov_iter *iov_iter;

@@ -62,7 +62,7 @@ static bool virtio_transport_can_zcopy(const struct 
virtio_transport *t_ops,
                int pages_to_send = iov_iter_npages(iov_iter, MAX_SKB_FRAGS);

                /* +1 is for packet header. */
-               return t_ops->can_msgzerocopy(pages_to_send + 1);
+               return t_ops->can_msgzerocopy(cid, pages_to_send + 1);
        }

        return true;
@@ -375,7 +375,7 @@ static int virtio_transport_send_pkt_info(struct vsock_sock 
*vsk,
                        info->msg->msg_flags &= ~MSG_ZEROCOPY;

                if (info->msg->msg_flags & MSG_ZEROCOPY)
-                       can_zcopy = virtio_transport_can_zcopy(t_ops, info, 
pkt_len);
+                       can_zcopy = virtio_transport_can_zcopy(t_ops, info, 
pkt_len, src_cid);

                if (can_zcopy)
                        max_skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE,
--
2.34.1