[openib-general] Some Missing Features from mthca/user MAD access

[Roland Dreier]

> The simplest approach I think is, keep some file open, when its closed
> (which happends automatically when the process dies) clean the is_sm bit.

This does seem to be the simplest approach.  However, there are two issues
I'm still trying to figure out:

 - Where should the file be?  Do we really want to create a bunch of issm
   files in /dev that only support open() and close()?  I can't think
of anything
   better, though.

 - How does this interact with the kernel's own use of the IsSM bit?  Should
   ib_port_modify() fail if an attempt to set the IsSM bit is made when the bit
   is already sent?

 - Roland