From: "A.N.Kuznetsov" <redacted>
Date: Tue, 27 Sep 2005 04:38:45 +0400
Actually, when this code was written, add_timer() behaved differently,
double add_timer() was prohibited and it printked
"bug: kernel timer added twice at...".
Yes, it calls __mod_timer() now. That's quite bad and
the debugging check should be re-added I think.
Is there some reason why we want add_timer() to behave like
__mod_timer(timer, timer->expires)? I can't see any...
So perhaps we should add the simple BUG_ON(timer->pending) check to
include/linux/timer.h:add_timer()
add_timer_on() does this check btw....