[linux-pm] [PATCH 05/13] PM: Add option to disable /sys/power/state interface

[Rafael J. Wysocki]

On Monday 09 February 2009, Pavel Machek wrote:
> > On Monday 09 February 2009, Pavel Machek wrote:
> > > On Sun 2009-02-08 15:00:38, Arve Hj?nnev?g wrote:
> > > > On Sun, Feb 8, 2009 at 1:40 PM, Alan Stern <stern at rowland.harvard.edu> wrote:
> > > > > On Sun, 8 Feb 2009, Pavel Machek wrote:
> > > > >
> > > > >> Well, it is true that wakelocks could be single atomic_t ... but they
> > > > >> would make them undebuggable. Ok, wakelock interface sucks. But I
> > > > >> believe something like that is neccessary.
> > > > >
> > > > > krefs don't have name strings for keeping track of who has been
> > > > > incrementing or decrementing their counters.  And it's true that krefs
> > > > > are nearly undebuggable.  But somehow we've managed to struggle along
> > > > > without adding names to krefs.  Why should wakelocks be any different?
> > > > 
> > > > It sounds like you suggesting that we add another nearly undebuggable interface.
> > > > 
> > > > Using only a single atomic_t would not allow us to use a wakelock a
> > > > switch, or to specify a timeout. You could replace the list in the
> > > > implementation with a single atomic_t by adding more state to each
> > > > wakelock, but I like my current solution better.
> > > 
> > > For the record, I agree here. And... if struct wakelock contains char
> > > * or not is a very small detail.
> > 
> > It really isn't, because it means allocating (kernel) memory for each wakelock,
> > to store the name.
> 
> If it can be #ifdef DEBUG or something, I don't see a problem. And it
> does not need to allocate anything, most wakelocks will be just
> static. So we are talking about 10bytes per wakelock of overhead --
> not too bad.

No, we are talking of allocating kernel memory on behalf of user space
processes with no apparent limitations.

Thanks,
Rafael