Re: PATCH: Improvements in shrink_mmap and kswapd

[Roger Larsson <roger.larsson@norran.net>]

Philipp Rumpf wrote:
> 
> On Sun, Jun 18, 2000 at 01:30:17AM +0200, Roger Larsson wrote:
> > > diff -urN --exclude-from=/home/lfcia/quintela/work/kernel/exclude base/include/asm-i386/bitops.h working/include/asm-i386/bitops.h
> > > --- base/include/asm-i386/bitops.h      Sat Jun 17 23:37:03 2000
> > > +++ working/include/asm-i386/bitops.h   Sat Jun 17 23:52:49 2000
> > > @@ -29,6 +29,7 @@
> > >  extern void change_bit(int nr, volatile void * addr);
> > >  extern int test_and_set_bit(int nr, volatile void * addr);
> > >  extern int test_and_clear_bit(int nr, volatile void * addr);
> > > +extern int test_and_test_and_clear_bit(int nr, volatile void * addr);
> > >  extern int test_and_change_bit(int nr, volatile void * addr);
> > >  extern int __constant_test_bit(int nr, const volatile void * addr);
> > >  extern int __test_bit(int nr, volatile void * addr);
> > > @@ -87,6 +88,13 @@
> > >                 :"=r" (oldbit),"=m" (ADDR)
> > >                 :"Ir" (nr));
> > >         return oldbit;
> > > +}
> > > +
> > > +extern __inline__ int test_and_test_and_clear_bit(int nr, volatile void *addr)
> > > +{
> > > +       if(!(((unsigned long)addr) & (1<<nr)))
> > > +               return 0;
> > > +       return test_and_clear_bit(nr,addr);
> > >  }
> >
> >
> > This does not look correct. It basically tests if the ADDRESS has bit
> > #nr set...
> >
> > Shouldn't it be
> > +       if(!(((unsigned long)*addr) & (1<<nr)))
> 
> if(!((*(unsigned long *)addr) & (1<<nr))
> 
> is closer to what you want. it still breaks for nr > BITS_PER_LONG.


Final attempt:

return test_bit(nr,addr) && test_and_clear_bit(nr,addr);

It even matches the name :-)
But it have to be moved some lines down.
(Exercise for the reader)

/RogerL
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