Re: [PATCH] sctp: do not mark chunk abandoned if peer has no PRSCTP capable

[Vlad Yasevich <vladislav.yasevich@hp.com>]

On Fri, 2011-03-04 at 13:10 +0800, Wei Yongjun wrote:
> > On 03/02/2011 11:20 PM, Wei Yongjun wrote:
> >> Chunk is marked abandoned if the chunk is expires, and it not be
> >> retransmited even if the peer has no PRSCTP capable, but the peer
> >> will still wait for retransmit it to update CTSN.
> >> This patch disable mark chunk abandoned if peer has no PRSCTP
> >> capable.
> >>
> >> Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
> >> ---
> >>  net/sctp/chunk.c |    3 +++
> >>  1 files changed, 3 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
> >> index 6c85564..0d4832d 100644
> >> --- a/net/sctp/chunk.c
> >> +++ b/net/sctp/chunk.c
> >> @@ -347,6 +347,9 @@ int sctp_chunk_abandoned(struct sctp_chunk *chunk)
> >>  {
> >>  	struct sctp_datamsg *msg = chunk->msg;
> >>  
> >> +	if (!chunk->asoc->peer.prsctp_capable)
> >> +		return 0;
> >> +
> >>  	if (!msg->can_abandon)
> >>  		return 0;
> >>  
> > The trouble is that timetolive can be set on a message independent of Partial Reliability.
> > The difference in behavior is that when PR can't be used, a chunk can only be abandoned
> > if it has not yet been transmitted.  With PR enabled, the chunk can be abandoned at any time.
> >
> > So, you can't blindly disallow abandonment. 
> 
> But, how can we do PR if peer has no PRSCTP capable?

That's already taken care of.  We report the message as unsent.  When
PRSCTP is disabled, you may only abandon messages/chunks that have not
been transmitted (assigned a TSN).

> Return error to application in sendmsg()? If so, how we check this if there is no asoc?

How would you have data without an association?

-vlad

> 
> 
> > -vlad
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