From af60d61fa846725566f4a876ae04f891bdff1c7a Mon Sep 17 00:00:00 2001 From: Kornilios Kourtis Date: Tue, 9 Jan 2018 09:52:22 +0100 Subject: [PATCH] doc: clarification about setting SO_ZEROCOPY Signed-off-by: Kornilios Kourtis Acked-by: Willem de Bruijn Signed-off-by: David S. Miller --- Documentation/networking/msg_zerocopy.rst | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst index 77f6d7e..291a012 100644 --- a/Documentation/networking/msg_zerocopy.rst +++ b/Documentation/networking/msg_zerocopy.rst @@ -72,6 +72,10 @@ 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 ------------ -- 2.7.4