Re: [patch 6/12] hold atomic kmaps across generic_file_read

Daniel Phillips
2002-08-12T09:40:23Z

On Monday 12 August 2002 09:45, Rusty Russell wrote:
> On Fri, 9 Aug 2002 18:33:09 -0700 (PDT)
> Linus Torvalds <torvalds@transmeta.com> wrote:
> > repeat:
> > kmap_atomic(..); // this increments preempt count
> > nr = copy_from_user(..);
>
> Please please please use a different name for "I know I'm not preemptible but
> I can handle it" or a flag or something.
>
> That leaves us with the possibility of a BUG() in the "normal" copy_to/from_user
> for all those "I'm holding a spinlock while copying to userspace wheeee!" bugs.
> Very common mistake for new kernel authors.

That's the whole point of this: it's not a bug anymore. (It's a feature.)

But agreed, a different name than preempt count would be nice, because it's
evolving away from its original function. Is this a 'monitor'? (I don't
think so.) Perhaps 'atomic_count' is more accurate.

--
Daniel