centos man page for mod_timer

MOD_TIMER(9)							   Driver Basics						      MOD_TIMER(9)

NAME
       mod_timer - modify a timer's timeout

SYNOPSIS
       int mod_timer(struct timer_list * timer, unsigned long expires);

ARGUMENTS
       timer
	   the timer to be modified

       expires
	   new timeout in jiffies

DESCRIPTION
       mod_timer is a more efficient way to update the expire field of an active timer (if the timer is inactive it will be activated)

       mod_timer(timer, expires) is equivalent to:

       del_timer(timer); timer->expires = expires; add_timer(timer);

       Note that if there are multiple unserialized concurrent users of the same timer, then mod_timer is the only safe way to modify the timeout,
       since add_timer cannot modify an already running timer.

       The function returns whether it has modified a pending timer or not. (ie.  mod_timer of an inactive timer returns 0, mod_timer of an active
       timer returns 1.)

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							      MOD_TIMER(9)