lkml.org 
[lkml]   [2006]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRE: Synchronizing Bit operations V2
On Thu, 30 Mar 2006, Chen, Kenneth W wrote:

> Christoph Lameter wrote on Thursday, March 30, 2006 5:13 PM
> > Then there will no barrier since clear_bit only has acquire semantics.
> > This is a bug in bit operations since smb_mb__before_clear_bit does
> > not work as documentted.
>
> Well, please make up your mind with:
>
> Option (1):
>
> #define clear_bit clear_bit_mode(..., RELEASE)
> #define Smp_mb__before_clear_bit do { } while (0)
> #define Smp_mb__after_clear_bit smp_mb()
>
> Or option (2):
>
> #define clear_bit clear_bit_mode(..., ACQUIRE)
> #define Smp_mb__before_clear_bit smp_mb()
> #define Smp_mb__after_clear_bit do { } while (0)
>
> I'm fine with either one.

Neither one is correct because there will always be one combination of
clear_bit with these macros that does not generate the required memory
barrier.

-
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: 2006-03-31 03:40    [W:0.057 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site