lkml.org 
[lkml]   [2006]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] Document Linux's memory barriers [try #4]
Date
Paul Mackerras <paulus@samba.org> wrote:

> No, that's not the problem. The problem is that you can get q == &b
> and d == 1, believe it or not. That is, you can see the new value of
> the pointer but the old value of the thing pointed to.

But that doesn't make any sense!

That would mean we that we'd've read b into d before having read the new value
of p into q, and thus before having calculated the address from which to read d
(ie: &b) - so how could we know we were supposed to read d from b and not from
a without first having read p?

Unless, of course, the smp_wmb() isn't effective, and the write to b happens
after the write to p; or the Alpha's cache isn't fully coherent.

David
-
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: 2006-03-15 01:02    [W:0.056 / U:1.180 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site