RE: [PATCH] RDMA/nes: Adding queue drain functions

["Steve Wise" <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

> > The iWARP Verbs spec mandates that when the QP is in ERROR, post_send() and
> > post_recv() must, at some point, fail synchronously.  See:
> >
> > http://tools.ietf.org/html/draft-hilland-rddp-verbs-00#section-6.2.4
> 
> OK,
> I see it, the iWARP devices need to flush QP before moving to
> drain(error) state.
> 
> This leads to another question, why don't we have common specific
> functions for iWARP devices? Right now, we have two drivers with the
> similar code.
> 

Based on the initial review/discussion of the drain API, it was agreed that the
drain logic wouldn't have IB and IW cases, but rather a common and
device-specific case. 

> The suggested refactoring can be as follows:
> 
> post_marker_func(..)
> {
>     post_send ....
> }
> 
> ib_drain_qp(..)
> {
>     move_to_error
>     call_post_marker_func
> }
> 
> iw_drain_qp(..)
> {
>     call_to_post_marker_func
>     move_to_drain
> }
>

This won't work if the QP is already in out of RTS which happens as part of
rdma_disconnect().  And currently the ULP usage is to disconnect and then drain.

Steve.


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