Re: [patch 2.6.24-rc2 1/3] generic gpio -- gpio_chip support

[David Brownell <david-b@pacbell.net>]

On Tuesday 13 November 2007, Nick Piggin wrote:
> > All this does is prevent constant and needless checking for
> > "do you want to preempt me now?" "now?" "now?" in "now?" the
> > middle "now?" of "now?" i/o "now?" loops.
> 
> Actually that's wrong.

Certainly it's right for the mainstream kernel.  Dropping a
lock (other than a raw spinlock) does that checking; when a
loop needs to acquire then drop such a lock, that's exactly
what's going on.

And in the RT kernel, it's got to do the same thing ...
because dropping that lock may mean that a higher priority
task should immediately run and grab the lock.