Hi,
                                                                                                                                                    
I started hitting this problem when using httperf, upon investigation
it seems to be easily triggered when you make gettimeofday() calls in
very close succession (just doing them in a tight loop easily
replicates the problem).
                                                                                                                                                    
I think the problem is that in itc_get_offset() there is a race
between getting the now value and calculating the last_tick from
itm_next; if we are interrupted between the two itm_next will be set
after now.
                                                                                                                                                    
Suggested patch attached; note the fsyscall implementation does not
appear to have this problem.
                                                                                                                                                    
-i
ianw@gelato.unsw.edu.au
http://www.gelato.unsw.edu.au