netdev - [PATCH net-next 0/4] shrink struct ubuf

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Date:   Fri, 23 Sep 2022 17:39:00 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     netdev@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org, Wei Liu <wei.liu@...nel.org>,
        Paul Durrant <paul@....org>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [PATCH net-next 0/4] shrink struct ubuf_info

struct ubuf_info is large but not all fields are needed for all
cases. We have limited space in io_uring for it and large ubuf_info
prevents some struct embedding, even though we use only a subset
of the fields. It's also not very clean trying to use this typeless
extra space.

Shrink struct ubuf_info to only necessary fields used in generic paths,
namely ->callback, ->refcnt and ->flags, which take only 16 bytes. And
make MSG_ZEROCOPY and some other users to embed it into a larger struct
ubuf_info_msgzc mimicking the former ubuf_info.

Note, xen/vhost may also have some cleaning on top by creating
new structs containing ubuf_info but with proper types.

Pavel Begunkov (4):
  net: introduce struct ubuf_info_msgzc
  xen/netback: use struct ubuf_info_msgzc
  vhost/net: use struct ubuf_info_msgzc
  net: shrink struct ubuf_info

 drivers/net/xen-netback/common.h    |  2 +-
 drivers/net/xen-netback/interface.c |  4 +--
 drivers/net/xen-netback/netback.c   |  7 +++---
 drivers/vhost/net.c                 | 15 ++++++------
 include/linux/skbuff.h              | 11 +++++++--
 net/core/skbuff.c                   | 38 ++++++++++++++++-------------
 net/ipv4/ip_output.c                |  2 +-
 net/ipv4/tcp.c                      |  2 +-
 net/ipv6/ip6_output.c               |  2 +-
 9 files changed, 48 insertions(+), 35 deletions(-)

-- 
2.37.2