On Tue, Mar 28, 2017 at 12:17:00PM +0800, Xin Long wrote:
> On Tue, Mar 28, 2017 at 6:43 AM, Marcelo Ricardo Leitner
> <marcelo.leitner@xxxxxxxxx> wrote:
> > On Mon, Mar 27, 2017 at 12:21:15AM +0800, Xin Long wrote:
> >> David Laight noticed the support for MSG_MORE with datamsg->force_delay
> >> didn't really work as we expected, as the first msg with MSG_MORE set
> >> would always block the following chunks' dequeuing.
> >>
> >> This Patch is to rewrite it by saving the MSG_MORE flag into assoc as
> >> David Laight suggested.
> >>
> >> asoc->force_delay is used to save MSG_MORE flag before a msg is sent.
> >> All chunks in queue would not be sent out if asoc->force_delay is set
> >> by the msg with MSG_MORE flag, until a new msg without MSG_MORE flag
> >> clears asoc->force_delay.
> >>
> >> Note that this change would not affect the flush is generated by other
> >> triggers, like asoc->state != ESTABLISHED, queue size > pmtu etc.
> >>
> >> v1->v2:
> >> Not clear asoc->force_delay after sending the msg with MSG_MORE flag.
> >>
> >> Fixes: 4ea0c32f5f42 ("sctp: add support for MSG_MORE")
> >> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
> >> ---
> >> include/net/sctp/structs.h | 2 +-
> >> net/sctp/output.c | 2 +-
> >> net/sctp/socket.c | 2 +-
> >> 3 files changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> >> index 592dece..8caa5ee 100644
> >> --- a/include/net/sctp/structs.h
> >> +++ b/include/net/sctp/structs.h
> >> @@ -499,7 +499,6 @@ 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 */
> >> };
> >>
> >> @@ -1878,6 +1877,7 @@ struct sctp_association {
> >>
> >> __u8 need_ecne:1, /* Need to send an ECNE Chunk? */
> >> temp:1, /* Is it a temporary association? */
> >> + force_delay:1,
> >> prsctp_enable:1,
> >> reconf_enable:1;
> >>
> >> diff --git a/net/sctp/output.c b/net/sctp/output.c
> >> index 1224421..73fd178 100644
> >> --- a/net/sctp/output.c
> >> +++ b/net/sctp/output.c
> >> @@ -704,7 +704,7 @@ static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet,
> >> */
> >>
> >> if ((sctp_sk(asoc->base.sk)->nodelay || inflight == 0) &&
> >> - !chunk->msg->force_delay)
> >> + !asoc->force_delay)
> >
> > How is this going to not block the flush on asoc->state != ESTABLISHED?
> > AFAICT b7018d0b6300 ("sctp: flush out queue once assoc state falls into
> > SHUTDOWN_PENDING") need to clear asoc->force_delay too.
>
> It won't block the flush on asoc->state != ESTABLISHED,
> in sctp_packet_can_append_data [1].
>
> 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 (!sctp_state(asoc, ESTABLISHED)) <-----[1]
> return SCTP_XMIT_OK;
Ah yes, okay.
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
>
>
>
> >
> > Case I have in mind is the same old one:
> > - app send a msg with MSG_MORE
> > - close the asoc, without sending the final msg
> >
> >> /* Nothing unacked */
> >> return SCTP_XMIT_OK;
> >>
> >> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> >> index 0f378ea..baa269a 100644
> >> --- a/net/sctp/socket.c
> >> +++ b/net/sctp/socket.c
> >> @@ -1965,7 +1965,7 @@ 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);
> >> + asoc->force_delay = !!(msg->msg_flags & MSG_MORE);
> >>
> >> /* Now send the (possibly) fragmented message. */
> >> list_for_each_entry(chunk, &datamsg->chunks, frag_list) {
> >> --
> >> 2.1.0
> >>
> >> --
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