Use https and link to the patch directly.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

MSG_ZEROCOPY implementation for UDP was merged in v5.0,
6e360f73 ("Merge branch 'udp-msg_zerocopy'").

Signed-off-by: Petr Vorel <pvorel@suse.cz>
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>

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>

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>