[ewg] Re: pkey change handling patch

[Roland Dreier]

 > So since all this thread was started by Moni because of IPoIB,
 > the path is clear in that respect, and would already be a step in the
 > right direction:
 > 
 > - a patch to add ib_find_pkey() and ib_find_gid() to core
 > - a patch to replace cache usage in IPoIB / SRP with uncached
 >   hardware accesses on top of this
 > - pkey change handling patch on top of these

Makes good sense to me.

 > 
 > I *think* we can keep this provider-specific cache updated by snooping incoming
 > MADs in driver.  And if it can be done this way, in all providers, we might be able to
 > simply require that query_pkey/query_gid in providers do not sleep.
 > If that's true, we'll save ourselves the work of auditing core - ib_find_pkey()
 > and ib_find_gid() will be a drop-in replacement for cache.
 > 
 > Roland, what do you think?

I'm not sure I like changing the rules for query_pkey/query_gid -- I
think slow-path operations like that should be able to sleep.  And in
particular, ehca does a hypercall in query_pkey that seems to sleep,
and it seems quite possible that other adapters may need to do similar
things in the future if they have an internal SMA (that makes snooping
MADs impossible).

 - R.