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Commit ced68234 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
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sock: remove zerocopy sockopt restriction on closed tcp state 



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: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 29d1df72

Documentation/networking/msg_zerocopy.rst

+0 −5
Original line number Diff line number Diff line
@@ -72,11 +72,6 @@ this flag, a process must first signal intent by setting a socket option: 
	if (setsockopt(fd, SOL_SOCKET, SO_ZEROCOPY, &one, sizeof(one)))

		error(1, errno, "setsockopt zerocopy");



Setting the socket option only works when the socket is in its initial

(TCP_CLOSED) state.  Trying to set the option for a socket returned by accept(),

for example, will lead to an EBUSY error. In this case, the option should be set

to the listening socket and it will be inherited by the accepted sockets.



Transmission

------------

net/core/sock.c

+0 −2
Original line number Diff line number Diff line
@@ -1052,8 +1052,6 @@ int sock_setsockopt(struct socket *sock, int level, int optname, 
		if (sk->sk_family == PF_INET || sk->sk_family == PF_INET6) {

			if (sk->sk_protocol != IPPROTO_TCP)

				ret = -ENOTSUPP;

			else if (sk->sk_state != TCP_CLOSE)

				ret = -EBUSY;

		} else if (sk->sk_family != PF_RDS) {

			ret = -ENOTSUPP;

		}