[openib-general] [PATCH] librdmacm: fix bug causing failure to work with partial membership pkey

[Hal Rosenstock]

On Thu, 2007-02-22 at 03:04, Or Gerlitz wrote:
> Sean Hefty wrote:
> >> Note that since the HCA validates the pkey in the in coming packet, no
> >> matter what the IB SW would do, partial members of a partition can't
> >> talk to each other. So the approach taken by the core/ipoib code was
> >> to just ignore the MSb in places where the code looks for the pkey
> >> --index-- and use the full member pkey when forming MGIDs. This seems
> >> fine to me.
> 
> > My concern is that ib_find_cached_pkey() returns an index to a pkey that wasn't 
> > the one in the search.  Can this lead to a QP being configured in such a way 
> > that communication with a remote QP would silently fail?
> 
> My understanding is that when an IPoIB broadcast domain contains both 
> partial and full members (*) attempts to communicate between two partial 
> members would silently fail,

An IB multicast group _cannot_ have partial members so this never should
get far enough to where two limited members would be unable to
communicate.

-- Hal

> does this silence is something you think we 
> should work to change?
> 
> (*) eg when you have bunch or clients and a server or bunch of servers 
> and you don't want to allow --clients-- to communicate among themselves)
> 
> > I'm not against this patch, but I want to make sure that I understand the 
> > issues, so we're not creating a work-around solution.  The patch is against the 
> > librdmacm, yet there's nothing that I see in the librdmacm that makes me think 
> > it's behaving incorrectly.
> 
> My thinking is that if in the end of this thread we are willing to move 
> forward without changing ib_find_cached_pkey() then this patch should be 
> merged.
> 
> Or.