[PATCH RESEND V3 net-next 0/3] RDS: optimized notification for zerocopy completion

[Sowmini Varadhan <sowmini.varadhan@oracle.com>]

Resending with acked-by additions: previous attempt does not show
up in Patchwork.

RDS applications use predominantly request-response, transacation
based IPC, so that ingress and egress traffic are well-balanced,
and it is possible/desirable to reduce system-call overhead by
piggybacking the notifications for zerocopy completion response
with data.

Moreover, it has been pointed out that socket functions block
if sk_err is non-zero, thus if the RDS code does not plan/need
to use sk_error_queue path for completion notification, it
is preferable to remove the sk_errror_queue related paths in
RDS.

Both of these goals are implemented in this series.

v2: removed sk_error_queue support
v3: incorporated additional code review comments (details in each patch)

Sowmini Varadhan (3):
  selftests/net: revert the zerocopy Rx path for PF_RDS
  rds: deliver zerocopy completion notification with data
  selftests/net: reap zerocopy completions passed up as ancillary data.

 include/uapi/linux/errqueue.h              |    2 -
 include/uapi/linux/rds.h                   |    7 ++
 net/rds/af_rds.c                           |    7 +-
 net/rds/message.c                          |   38 ++++-----
 net/rds/rds.h                              |    2 +
 net/rds/recv.c                             |   31 +++++++-
 tools/testing/selftests/net/msg_zerocopy.c |  120 ++++++++++++----------------
 7 files changed, 111 insertions(+), 96 deletions(-)