Re: owner field in `struct fs'

[Rusty Russell]

In message <[e-mail]> you write:
> Rusty Russell wrote:
> > AFAIK his work never went in/was never completed 8( So del_timer_sync
> > doesn't work on self-deleting timers.
> 
> His work was a masterpiece.  Linus was looking at the timer_exit()
> abomination last week and I sent a smorgasbord of patches which remove
> it.  Hoping to see one come back at us soon.

Excellent; I'm extremely grateful for this work...

> But del_timer_sync(), like del_timer() still must not be used on
> self-kfreeing timers.  I think a variant could be made to do so quite
> easily (esp. if Linus chooses the right patch).
> 
> - grab the timerlist_lock
> - see if any timers are running.  If so, unlock and retry.
> - walk the tvecs looking for the timer.

No, delete_self_deleting_timer_sync() would look like:

	- grab the timerlist_lock
	- detach_timer
	- if that succeeds, release lock
	- if that failed:
		- if timer is running now, release lock, spin until its done
		- if timer isn't running, release lock, BUG()

This is required, because if you call `del_timer(&timer)' you *need*
to know (because you have your own spinlocks) that it hasn't run yet,
or is running at the moment.  That's because if it's finished running,
you might now be deleting a completely unrelated timer...

Enjoy!
Rusty.
--
Hacking time.