lkml.org 
[lkml]   [2006]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [patch] i386: make bitops safe
Date
On Tuesday 28 February 2006 00:06, Linus Torvalds wrote:
> On Mon, 27 Feb 2006, Chuck Ebbert wrote:
> > Make i386 bitops safe. Currently they can be fooled, even on
> > uniprocessor, by code that uses regions of the bitmap before
> > invoking the bitop. The least costly way to make them safe
> > is to add a memory clobber and tag all of them as volatile.
>
> Actually, the least costly way should be to make the "ADDR" define work
> right again.
>
> It used to do something magic like

I remember asking rth about this at some point and IIRC
he expressed doubts if it would actually do what expected. Richard?

-Andi

>
> struct fake_area {
> unsigned long members[1000];
> };
>
> #define ADDR (*(volatile struct fake_area *)addr)
>
> which was correct. I forget why it got broken into using just a "long *"
> (it happened a long long time ago).
>
> Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-02-28 00:48    [W:0.043 / U:1.588 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site