doc: clarification about setting SO_ZEROCOPY

Signed-off-by: Kornilios Kourtis <[email protected]> Acked-by: Willem de Bruijn <[email protected]> Signed-off-by: David S. Miller <[email protected]>
vieko · Jan 10, 2018 · af60d61 · af60d61
1 parent 11d827a
commit af60d61
Showing 1 changed file with 4 additions and 0 deletions.
diff --git 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
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