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>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 387c802bf248fe60adac88fc47e021a7d38188e6..a244db5e5ff7fa65bcf0a4124cbbe5f4682e6d9d 100644 (file)
--- 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 */
 };
 

diff --git a/net/sctp/output.c b/net/sctp/output.c
index 814eac047467c5b9fe8fdb4dd6b21a57812b3e1f..85406d5f8f41e739738c51988e4a093f1859b000 100644 (file)
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -704,18 +704,15 @@ static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet,
         * unacknowledged.
         */
 
-       if (sctp_sk(asoc->base.sk)->nodelay)
-               /* Nagle disabled */
+       if ((sctp_sk(asoc->base.sk)->nodelay || inflight == 0) &&
+           !chunk->msg->force_delay)
+               /* Nothing unacked */
                return SCTP_XMIT_OK;
 
        if (!sctp_packet_empty(packet))
                /* Append to packet */
                return SCTP_XMIT_OK;
 
-       if (inflight == 0)
-               /* Nothing unacked */
-               return SCTP_XMIT_OK;
-
        if (!sctp_state(asoc, ESTABLISHED))
                return SCTP_XMIT_OK;
 

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 75f35cea43713856a613e04a933696fb870ba171..b5321486fbed300106844584d1764181342d8e35 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1964,6 +1964,7 @@ static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
                err = PTR_ERR(datamsg);
                goto out_free;
        }
+       datamsg->force_delay = !!(msg->msg_flags & MSG_MORE);
 
        /* Now send the (possibly) fragmented message. */
        list_for_each_entry(chunk, &datamsg->chunks, frag_list) {