linux.git/Documentation/networking/msg_zerocopy.rst, branch v4.20 Linux kernel source tree sock: remove zerocopy sockopt restriction on closed tcp state 2018-03-14T16:51:28+00:00 Willem de Bruijn willemb@google.com 2018-03-14T16:49:19+00:00 ced68234b6a244355aeab07c2681bc49f695eaed Socket option SO_ZEROCOPY determines whether the kernel ignores or processes flag MSG_ZEROCOPY on subsequent send calls. This to avoid changing behavior for legacy processes. Limiting the state change to closed sockets is annoying with passive sockets and not necessary for correctness. Once created, zerocopy skbs are processed based on their private state, not this socket flag. Remove the constraint. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Socket option SO_ZEROCOPY determines whether the kernel ignores or
processes flag MSG_ZEROCOPY on subsequent send calls. This to avoid
changing behavior for legacy processes.

Limiting the state change to closed sockets is annoying with passive
sockets and not necessary for correctness. Once created, zerocopy skbs
are processed based on their private state, not this socket flag.

Remove the constraint.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
doc: clarification about setting SO_ZEROCOPY 2018-01-10T20:01:49+00:00 Kornilios Kourtis kou@zurich.ibm.com 2018-01-09T08:52:22+00:00 af60d61fa846725566f4a876ae04f891bdff1c7a Signed-off-by: Kornilios Kourtis <kou@zurich.ibm.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Kornilios Kourtis <kou@zurich.ibm.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
doc: document MSG_ZEROCOPY 2017-09-01T17:39:35+00:00 Willem de Bruijn willemb@google.com 2017-09-01T16:01:41+00:00 cc8889ae8298ebfc6bbf52ad98fe3b5afdf4ae70 Documentation for this feature was missing from the patchset. Copied a lot from the netdev 2.1 paper, addressing some small interface changes since then. Changes v1 -> v2 - change email discussion URL format - clarify that u32 counter is per-syscall, unsigned and wraps after UINT_MAX calls - describe errno on send failure specific to MSG_ZEROCOPY - a few very minor rewordings Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
Documentation for this feature was missing from the patchset.
Copied a lot from the netdev 2.1 paper, addressing some small
interface changes since then.

Changes
  v1 -> v2
    - change email discussion URL format
    - clarify that u32 counter is per-syscall, unsigned and
      wraps after UINT_MAX calls
    - describe errno on send failure specific to MSG_ZEROCOPY
    - a few very minor rewordings

Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>