Subj : Re: double-checked locking in C
To   : comp.programming.threads
From : Laurent Deniau
Date : Fri Jul 08 2005 10:44 am

David Schwartz wrote:
> "Laurent Deniau" <Laurent.Deniau@cern.ch> wrote in message 
> news:42CD77A5.80601@cern.ch...
> 
> 
>>Volatile forbids reordering so reodering is not an issue. Visibility is 
>>one since it does not exist in the C norm.
> 
> 
>     Volatile does not forbid reordering. You are misunderstanding what the C 
> standard means when it says "reordering". It certainly, for example, does 

No.

> not mean that bus transactions to memory occur in the specified order, 
> because the C standard does not even assume that there is such a bus.

Right. Comming back to the example, returning from a function is a 
sequence point. Therefore, if initialized is volatile, C does not allow 
to assign it before it returns from the call with a stable value. I have 
no consideration about bus and such low level stuffs.

ld.

.