sctp: add support for MSG_MORE

This patch is to add support for MSG_MORE on sctp.

It adds force_delay in sctp_datamsg to save MSG_MORE, and sets it after
creating datamsg according to the send flag. sctp_packet_can_append_data
then uses it to decide if the chunks of this msg will be sent at once or
delay it.

Note that unlike [1], this patch saves MSG_MORE in datamsg, instead of
in assoc. As sctp enqueues the chunks first, then dequeue them one by
one. If it's saved in assoc,the current msg's send flag (MSG_MORE) may
affect other chunks' bundling.

Since last patch, sctp flush out queue once assoc state falls into
SHUTDOWN_PENDING, the close block problem mentioned in [1] has been
solved as well.

[1] https://patchwork.ozlabs.org/patch/372404/

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 387c802bf248..a244db5e5ff7 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -497,6 +497,7 @@ struct sctp_datamsg {
 	/* Did the messenge fail to send? */
 	int send_error;
 	u8 send_failed:1,
+	   force_delay:1,
 	   can_delay;	    /* should this message be Nagle delayed */
 };