Re: bitmaps/bitops

[Paul Mackerras <paulus@samba.org>]

Pete Zaitcev writes:

> > but the prototype for test_and_set_bit() depends on $(ARCH), and it's
> > not consistent, with the second arg (bitmap address) being one of:
> >   volatile void *
> >   void *
> >   volatile unsigned long *
> 
> It should be unsigned long pointer. I have no idea why
> volatile is still alive. Perhaps Linus can remember why he
> left it in on is386. Other arch maintainers midnlessly ape him
> in this area. I think I even kept his e-mail where he explains
> why volatile has to go.

The volatile is there (at least in ppc) because without it you get
compile warnings.  I don't see why the bitops particularly should be
the anti-volatile police.  I agree that using volatile is usually a
bad idea (unless you are accessing a memory-mapped I/O device).

Paul.