(no subject)

[Hettinger Tamas]

Hi everybody !

I've been developing a kernel module and I needed some timer functions. I
found init_timer() add_timer() del_timer() etc... but I would ask some
questions about them.

1) When I set a timer, it is added to a timer_list chain with add_timer().
If the time is up and the scheduled function is called, should I remove the
timer_list struct from the chain via del_timer() ? Or is it removed
automatically ?

2) How can a module safely removed if it has some running timers ? I have to
call del_timer() in cleanup_module() for each running timer ? And what's the
purpose of the timer_pending function ?

thanks

Re:

[Jonathan Corbet]

> 1) When I set a timer, it is added to a timer_list chain with add_timer().
> If the time is up and the scheduled function is called, should I remove the
> timer_list struct from the chain via del_timer() ? Or is it removed
> automatically ?

It will be removed automatically, just before your timer function is called.

> 2) How can a module safely removed if it has some running timers ? I have to
> call del_timer() in cleanup_module() for each running timer ? 

You cannot remove a module (safely) if there are outstanding timers.  Use
del_timer_sync() to get rid of them and ensure they aren't running on
another processor.

Chapter 6 of Linux Device Drivers covers this topic; see:

	http://www.xml.com/ldd/chapter/book/ch06.html

jon