vsock: report pending receive data to io_uring

AF_VSOCK stream receives never fill msghdr.msg_inq, so io_uring cannot set
IORING_CQE_F_SOCK_NONEMPTY and retries a multishot receive even after the
queue has been drained.

Fill the hint at the common receive exit using the transport callback that
SIOCINQ already uses, and report 1 once the connection is finished so the
caller performs the receive which observes EOF, as TCP does after a FIN.

A vsock loopback ping-pong with io_uring multishot receive drops entries
into __vsock_connectible_recvmsg from 1.97 to 1.00 per delivered message,
and receiver CPU time by about 3% (25 runs of 50000 messages, p=0.006).

Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260923184008.153541-2-devnexen@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions