[PATCH] c/r: Add UTS support (v4)

[Dan Smith]

OL> What got me confused was that you loop over all tasks, which is
OL> not needed because was assume they all share the name nsproxy; And
OL> in restart, you unshare() many times by the same task, so all but
OL> the last unshare() are useless.  In other words, I wonder what is
OL> the need for that loop over all processes.

You're exactly right, but this wasn't my intent.  It was left over
from the first iteration of the patch.

OL> Here is a suggestion for a simple change that is likely to be a step
OL> towards more generic solution in the future:

OL> The nsprox is a property of a task, and it is (possibly) shared. We
OL> can put the data either on the pids_arr or on the cr_hdr_task itself.
OL> For simplicity (and to work with your scheme) let's assume the former.

OL> We can extend the pids_arr to have a ns_objref field, that will hold
OL> the objref of the nxproxy. Of course, now, all pids_arr will have the
OL> same objref, or else ...  This data will follow the pids_arr data in
OL> the image.

OL> During checkpoint, we read the pids_arr from the image, and then for
OL> each objref of an nsproxy that is seen for the first time, we read
OL> the state of that nsproxy and restore a new one. (In our simple case,
OL> there will always be exactly one).

Storing an objref of the nsproxy for each task to track changes at
that level is what I did, and is the reason for the gratuitous
unshare() that is left there.  The idea was only to unshare() when I
encountered a new nsproxy objref.

However, Dave had some comments on this, which he made only on IRC.
Dave do you want to document them here for the benefit of the list?

-- 
Dan Smith
IBM Linux Technology Center
email: danms at us.ibm.com