From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <20000617174201.A28257@puffin.external.hp.com>
Date: Sat, 17 Jun 2000 17:42:01 -0600
From: Philipp Rumpf <prumpf@puffin.external.hp.com>
Subject: Re: PATCH: Improvements in shrink_mmap and kswapd
References: <ytt3dmcyli7.fsf@serpe.mitica> <394C0A09.CD2CBF62@norran.net>
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In-Reply-To: <394C0A09.CD2CBF62@norran.net>; from Roger Larsson on Sun, Jun 18, 2000 at 01:30:17AM +0200
Sender: owner-linux-mm@kvack.org
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To: Roger Larsson <roger.larsson@norran.net>, "Juan J. Quintela" <quintela@fi.udc.es>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, lkml <linux-kernel@vger.rutgers.edu>, linux-mm@kvack.org, linux-fsdevel@vger.rutgers.edu
List-ID: <linux-mm.kvack.org>

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.

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