I think the test whether the timer value is in the past doesn't work
when jiffies overflow (i.e. expires = ULONG_MAX - 5, jiffies = expires
+ 10), but I'm not sure if I really understood what the code is
expected to do.
> ...
> } else if (expires < timer_jiffies) {
> /* can happen if you add a timer with expires == jiffies,
> * or you set a timer to go off in the past
> */
> insert_timer(timer, tv1.vec, tv1.index);
> } ...
-- Jan Echternach