This patch series introduce the support for ioctl(s) in AF_VSOCK.
The only ioctl currently available is SIOCOUTQ, which returns
the number of unsent or unacked packets. It is available for
SOCK_STREAM, SOCK_SEQPACKET and SOCK_DGRAM.

As this information is transport-dependent, a new optional callback
is introduced: unsent_bytes.

The first patch add ioctl support in AF_VSOCK, while the second
patch introduce support for SOCK_STREAM and SOCK_SEQPACKET
in all virtio-based transports: virtio_transport (G2H),
vhost-vsock (H2G) and vsock-loopback.

The latest patch introduce two tests for this new feature.
More details can be found in each patch changelog.

v2->v3
Applied all reviewers' suggetions:
    - Minor style and code changes
    - atomic_int replaced with an existing spin_lock.
Introduced lock_sock on ioctl call.
Rebased to latest net-next

v1->v2
Applied all Stefano's suggestions:
    - vsock_do_ioctl has been rewritten
    - ioctl(SIOCOUTQ) test is skipped when it is not supported
    - Minor variable/function name changes
    - rebased to latest net-next

Signed-off-by: Luigi Leonardi <redacted>
---
Luigi Leonardi (3):
      vsock: add support for SIOCOUTQ ioctl for all vsock socket types.
      vsock/virtio: add SIOCOUTQ support for all virtio based transports
      test/vsock: add ioctl unsent bytes test

 drivers/vhost/vsock.c                   |  4 +-
 include/linux/virtio_vsock.h            |  7 +++
 include/net/af_vsock.h                  |  3 ++
 net/vmw_vsock/af_vsock.c                | 60 +++++++++++++++++++++--
 net/vmw_vsock/virtio_transport.c        |  4 +-
 net/vmw_vsock/virtio_transport_common.c | 35 ++++++++++++++
 net/vmw_vsock/vsock_loopback.c          |  7 +++
 tools/testing/vsock/util.c              |  6 +--
 tools/testing/vsock/util.h              |  3 ++
 tools/testing/vsock/vsock_test.c        | 85 +++++++++++++++++++++++++++++++++
 10 files changed, 206 insertions(+), 8 deletions(-)
---
base-commit: 50b70845fc5c22cf7e7d25b57d57b3dca1725aa5
change-id: 20240626-ioctl_next-fbbcdd596063

Best regards,
-- 
Luigi Leonardi [off-list ref]